Madagascar

Direction des Mines et de la Géologie (DMG)

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The contribution of mining to total exports in 2010 amounted to 10.3%

Madagascar Mining News


Source: CIA Factbook



Legend


Geology
The eastern two thirds of Madagascar are underlain by voluminous Precambrian, Archean and Proterozoic, rocks of diverse character, sporadically intruded by Cretaceous to Neogene age basalts and rhyolites. The Archean sequences are found throughout the length of the Island and comprise gneiss, migmatites, charnockites, granitoid-migmatites, amphibolites, schist and greenstones. Paleoproterozoic rocks comprise paragneiss, granite-gneisss, charnockites, metasediments and schist. The western third is composed of two large basins of Mid-Paleozoic to Recent sedimentary rocks.


Mining

Madagascar is one of the world’s leading producers of sapphire as well as other coloured gemstones including ruby, multi-coloured tourmaline, emerald, amethyst, cordierite, aquamarine and garnet and also plays a significant role in the production of high quality flake graphite. Madagascar is the second largest producer of graphite in Africa accounting for 45% of total output, although production has declined over the last five years by 35%. Madagascar is the third largest producer of chromite in Africa accounting for 0.8 per cent of total output. The country also produces modest amounts of gold, phlogopitic mica, beryl, salt, gypsum and ornamental stone (labradorite, celestite, agate, jasper and rose quartz). Madagascar also has major resources of nickel, cobalt, copper, platinum group metals, titanium, zirconium, uranium, bauxite, iron ore, coal and tar sands. The giant Ambatovy lateritic nickel-cobalt project is to start production in 2011-12 with an annual capacity of 60,000 tonnes of Ni and 5,600 tonnes of Co. A major titanium sands project at Mandena started production in 2009 and will ramp up production to 750,000 tonnes of ilmenite, rutile and zircon per annum by 2012. Later phases of the project have potential to expand production to 2.2 Mt /yr.


Oil & Gas

The giant oil fields of Tsimiroro (heavy oil) and Bemolanga (ultra-heavy oil) with combined reserves currently estimated at around 11.5 billion barrels lie towards the west of the island. However, processing heavy oil using steam injection is technically difficult and expensive.

Maps and images


Aluminium

  • Rio Tinto-Alcan holds the mineral rights to the bauxite deposit Manantenina , near Fort Dauphin. The deposit was initially studied by Pechiney, which was then taken over by Alcan. According to experts, it is possible to produce about 3 million tonnes of alumina per year at full capacity, Due to the energy deficit in the country, it is not considered for the moment, to make on-site processing of alumina into aluminum. An access road will have to be constructed between the mine site and the new port to facilitate export. 

Chrome

  • Societe Kraomita Malagasy (Kraoma), which is Madagascar's main chromite producer, produces around 40,000 t/y of concentrates plus 80,000 t/y of lumpy ore from the Andriamana complex, and a further 20,000 t/y from the Befandriana mine.

  • Lemur Resources Ltd is a Madagascan focussed coal exploration company incorporated in Australia in November 2010. Lemur is the 100% shareholder of the Guernsey registered company, Coal of Madagascar Limited ("COM") which is the 99% Shareholder of the Malagasy registered company, Coal Mining Madagascar SARL (“CMM”). CMM has an interest in seven mining permits located in the Imalato Coal Basin, the initial focus being the Imaloto Coal Project.  This project contains a gross in situ JORC compliant inferred resource estimate of 175  million tonnes, which was defined through an initial two phase drilling program completed in 2008 and 2009. The Imaloto Coal Project is located in the Imaloto Coal Basin, which is the northern-most coal field in the greater Sakoa Basin of South West Madagascar.  Lemur will be commencing the Phase III work programme in July 2011, which has a primary objective of better defining the limits of the coal seams and to bring the current inferred resource up to the measured category.


Diamond

Click HERE for an overview


Changes in the mining act and the discovery of large gemstone quality diamonds in Madagascar have led to interest by international mining companies to acquire claims in the most prospective areas.
Two hundred million years ago, Madagascar formed part of the super-continent Gondwana. The western margin of Madagascar was attached to Africa (adjacent to Tanzania) and the eastern margin to India). This is of significance to diamond exploration, because both Tanzania and India contain numerous kimberlites, the intrusive rocks that can host diamonds. Madagascar has had very little systematic exploration for kimberlites. To date, no discoveries have been announced. There is strong evidence to suggest that diamondiferous kimberlites or related rocks may be present on the island. Two very large, gemstone quality diamonds were purchased by Diamond Fields International from alluvial sapphire miners in the Sud-Est region of Madagascar. These diamonds weighed 23.82 and 8.39 carats respectively. This is a significant discovery since no kimberlites are known to have been found on the island and the primary source of these diamonds still awaits discovery. According to government data, a number of other diamonds have been recovered in Madagascar over the past century.
  • Canada's Pan African Mining through its operating subsidiary, PAM Madagascar Sarl, holds 10-year research permits covering in excess of 3000 square kilometres in areas deemed prospective for diamond exploration in various regions of the country. The company commenced exploration in 2004 and announced that kimberlite indicator minerals had been recovered from an initial reconnaissance sample taken.
  •  In 2004, Majescor Resources reached an agreement with De Beers to form a joint venture to explore for diamonds in the cratonic areas Majescor holds rights to in northern and central Madagascar. In 2003 and 2004, De Beers has collected and processed 102 samples totaling 77 m3 in volume from areas of Madagascar selected for their diamond potential. The company spent over C$1,000,000 on the exploration programme and on the evaluation of samples. The company's analysis led to the recovery of 4,378 visually positive kimberlitic indicators, some of which have been confirmed, through micro probing, as having a kimberlitic origin. In 2005 Majescor had found some kimberlite samples, but it turned out to be sterile, however, the company continued to carry out diamond exploration. (Source: MBendi)

Gold in Madagascar

Gold Home

Madagascar’s gold deposits are possibly mostly Precambrian in age and mainly mesothermal lode type deposits, but there is also evidence of younger epithermal mineralization. 

Report on Gold in Madagascar (Source of extracts below from report by Camillo Premoli, Simon McDonald: http://www.smedg.org.au/Premoli.htm).

MADAGASCAR's GOLD DISTRICTS 

To avoid arbitrary new groupings of Madagascar's gold districts throughout the Database the classification proposed by the BRGM in 1985 has been maintained. 

The relationship of these gold districts with geology and tectonics is given respectively in Plates 1 and 2 of this Database. Most of the descriptions of the individual deposits have, however, been taken from various works by Besairie (1964, 1966, 1969) and supplemented by a number of other publications.

Betsiaka District




 Location and history

The district of Betsiaka (or Batsiaka-Andavakoera) is located in the extreme north of Madagascar about 80 km south of Antsiranana, (formerly Diego Suarez).  Access is easy: by plane to Antsiranana (daily flight by Air Madagascar, Boeing 737, see Appendix 4 for timetable) and then 131 km of surfaced road to Ambilobe. This town (comfortable hotel, telecommunications, airstrip) is central to the Andavakoera gold district. The first gold occurrence in this district was discovered in 1906 by Mr Mortages near the village of Betsiaka (31 km east of Ambilobe by surfaced road). In 1909 production had already reached 1.223 t/y and was the most important for the island (see table 1a). Production decreased rapidly after the beginning of WWI and slipped below 100 kgs in 1917. The total recorded production of the Betsiaka gold district has been 1/4 million oz - undoubtedly much larger if we consider the "unofficial" production still taking place today.

Geology

The mineralisation consists of gold disseminated in veins of quartz and baryte (BRGM type c) near the contact between the Basement and the Paleo-Mesozoic sedimentary sequence of the Diego basin (see sketch 6/1). The Basement consists of more or less migmatitic gneiss and micaschists in contact with a series of:
                  Permian clay-sandstones 
                  Triassic pelitic schists
                  The Isalo continental sandstones.
This sedimentary series is cut by intrusions of microsyenites, essexites, labradorites and lamprophyres. The quartz-baryte veins occur into the Basement and the Permian formations but not the Triassic schists. Galena and sphalerite are common accessory minerals in the veins, probably representing a remobilisation of earlier mineralisations which Besairie (p 269a) estimated at 360 MA my.

The vein's general strike is 50§ E. with several cross veins. The main vein system is generally parallel to the tectonic of the area, (sketch 7/4) and indeed of northern Madagascar. Hot springs (70§ C) are common in the area and their geochemical chracterisation would be unquestionably important (IMR's opinion).

The gold veins have a thickness of some decimetres but occasionally can reach one or two metres and strike for several kilometres. The gold-bearing quartz-baryte veins occur over a length of about 130 km - from Anaborano to Ampisikinana - but they are heavily mineralised only in the region of Andavakoera over about a 20 km strike. Probably because the presence of galena, Andavakoera gold is always silver-bearing (electrum) with a finesse in the range of only 700-800.
  
Contrary to the majority of other Malagasy goldfields, Andavakoera's gold production was essentially from primary sources. The mineralised quartz was extracted, crudely crushed and the gold recovered by panning.

Besairie (1966) indicates at least eight "important" underground mines in the Betsiaka gold district and they were (see sketch 7/4):

Bereziky          (*)
Sarova            (*)
Tambo             (*)
Ambilon
Raphias           (*)
Paul
Ranomafana        (*)
Komakorimalandy

Only of five (*) have we some records: see sketches 7/5 and 7/6. From these it would seem that Betsiaka gold was mainly hosted in basement gneiss and extremely close to contact with Permian sandstones. The underground works generally extended for only one of two levels 20 30 m apart, probably to the water table.

Andavakoera's underground development was an impressive 17 km. From 1919 no rich gold zone was intersected and 1,440 m of underground development turned out to be totally unproductive. It was stopped in 1921 and the plant was closed in 1922 for lack of sufficient ore to be treated. In 1934 an attempt to exploit (sluices) the Komakormalandy River alluvions was attempted but without success.
 In 1950 the Malagasy Mining Department (French at the time) carried out a new study of the gold potential of the region but its results (probably thought to be negative) were not divulged. Immediately afterwards even the artisanal production ceased, not to be seriously restarted until the late 1970s.

No obvious attempt had been made to try to mine all the mineralised quartz, trying to exploit a lower ore grade with larger tonnage. This underlines an uncanny resemblance with what happened in the Western Australian goldfields at the beginning of the century, long before the gold boom of the '80s showed that practically all the old "exhausted" mines could be worked economically at much lower grades than previously thought. It is suggested that the Betsiaka gold district should be re-evaluated with a similar approach (IMR's opinion).

Table 6 lists 11 recorded deposits for the Betsiaka gold district, all of them hard-rock
deposits.

Individual deposits

 Ranofanana


The Ranomafana gold vein was exploited by a large trench and two main underground works to about 40 m in depth (sketch 7/5). The mine produced about 1/4 t of gold. The nearby vein of Ambilon produced about 400 kg of gold to a depth of 60 m.
 In 1909 underground work began and a plant with a proper crusher was installed, but with disappointing results. Apparently the mineralisation was very erratic and generally more consistent along strike rather than in depth. The exploitable zones are of rather limited dimensions but occasionally some can reach up to 200 m strike, with depth exceeding 60 m. In the mineralised zones the gold grades are very irregular - from 0 to 300 g/t  with an average of 20 g/t over a 1,000 t [recorded] production. In some smaller zones the grades have been extremely high: up to 150 kg for 10 t of quartz treated, or 500 oz/t. The Ranomafana mine is the only one, for which records are available, that showed the depth of the mine seemed to been connected with the exhaustion of the high grade ore (and the contact gneiss/sandstones) rather than the meeting of the water table.  

 Bereziky

The Bereziky mine produced 800 kg of gold from a single pocket (pocket 1915, see sketch 7/6); this underlies the extremely erratic grades of the Betsiaka gold district. Between these very rich pockets the grade varied between 0 and 3 g/t gold, at the time considered totally uneconomical.
The gold of Bereziky mine is entirely hosted in the Basement micaschists over a strike of approximately 500 m.

TSARATANANA DISTRICT 



Location and history

The gold district of Tsaratanana is one of the oldest known in Madagascar although its production statistics are often combined with the adjacent gold province on Maevatanana. The two provinces can be considered one. Access can be by car to Antananarivo (a 6 hr drive) or more conveniently by plane to Mahajanga (direct flight from Antananarivo by Boeing 737, 7 days a week. See Appendix 4) and then by 153 km of surface road to Ambondronamany (modest accommodation, telecommunications, no licensed airstrip).

The Tsaratanana gold district can be coveniently examined from here. A 4WD vehicle is recommended, particularly in the rainy season (November-April). Conversely a charter plane can be landed at Tsaratanana township itself but no reliable vehicle hire or accommodation will be available there.
  
Geology

Gold in the Tsaratanana district occurs essentially in quartz veinlets. Paragenesis is complex: tourmaline, barytine, pyrite,  and silver, lead, bismuth, molybdenum, copper sulphides. These gold-bearing quartz veinlets occur within a variety of lithologies: migmatites, leptinites and above all gneisses of the Archean Vohibory System, a Ca-Fe-Mg rich complex.

The Tsaratanana goldfield seems to occur entirely within the Berofona Group (migmatites and anphibolites), with ages between 1750 and 1890 MA (Pb method). These formations have later been intruded by granite. Besairie (1964) indicates an age of 350 MA for these intrusions but this seems very debatable.

Other minerals occurring in the region are obviously pegmatitic ones such as beryl, columbite and quartz. Other mineralisations in the region are chromite, graphite and lead (economically exploited underground at Besaky, 16 55" S -47 25" E). A time correlation between the lead and gold mineralisation of the region is probable (IMR's opinion). 

According to the geological map N.4 of Madagascar (1:500,000 Service Geologique) more than 20 gold prospects occur within a 100 km radius from Tsaratanana village. Some, surprisingly, are recorded over the sandstones of Isalo II sedimentary formations: these are, of course, alluvial deposits.
The gold-bearing veinlets of the primary occurrences strike N 45§ E and dip 35-60§ W. Their thickness varies between 15 and 90 cm, with grades between 2 and 11 g/t, but occasionally much higher: up to 10 oz/t at Ambatomisangana.
Table 6 lists 19 recorded deposits for the Tsaratanana gold district, most of them hard-rock deposits.

Individual deposits:


Ambatomitsangana

This is a small but very rich deposit located 4 km south of Tsaratanana and 1 km east of Ambatomitsangana, on the right shore of the Mahajamba R. The mineralisation is in a very rich (several ounces/t of Au) of quartz and galena with gold. The vein was only 20 m long.

Ambohipihaonana

This deposit occurs 35 km south of Tsaratanana. It has been prospected by the two small French companies "Syndacat Lyonnais" and "SociŠtŠ des Mines d'Ambatobe". The mineralisation exists in a vein of quartz and baryte with pyrite, chalcopyrite, sphaelarite  and occasionally bismuth and molybdenite. The presence of barytine is exceptional in a formation of Basement schists. The vein is concordant with the foliation of the intruded gneiss. The main vein, interbedded with the gneiss and migmatites, strikes on 400 m with a width between 15 and 90 cm. The vein's dip  is between 35§ and 60§; no direction is given (Bes D, 271a) but it probably dips to the west. There is a strong correlation between gold and sulphides. Grades vary between 2 and 11 g/t but it are much higher in the oxidation zone. This is, on average, 20 m deep. It is this zone that has been selectively exploited by French miners. The mine was still active in 1939, particularly in its southern sector, with four levels developed on 90 m of galleries, adits and cross-cuts. These works met with a gold bearing, quartz-sulphide lens developed over more than 300 m strike and plunging in several locations to 100 m below the outcrops. The vein's thickness ranged between 20 and 60 cm. Other works at 600 m to the north of the main mine, and particularly an adit of 112 m, have shown another vein with a thickness of about 60 cm. This and other mineralisations at 550 and 1950 m to the north graded 14.3 g/t Au with a total of 6,600 t of quartz crushed; but the recovery was probably poor. In 1939 Mr Delaitre, a competent French engineer, advised works in order to establish the average grade. His calculations indicated that a production based on 15,000 t/y would be economic with gold grades of 7 g/t or above.
As was common for the period the working on Ambohipihaonana started on an abnormally rich oxidised zone. The mine had an independent hydroelectric power plant which operated crushers and mills ("bocards"). This plant was destroyed by a fire and the deposit was abandoned.
  
Andranganala

This deposit occur 40 km south of Tsaratanana in a quartz-gold vein 0.25 to 0.40 m thick which has been followed to a depth of 40 m and along a strike of 250 m. Finely disseminated tourmaline and zircon are accessory minerals. The gold fineness is 858-900. Nearby a second quartz vein shows molybdenite and numerous inclusions of rutile and zircon. 
  
Ambararatakely

The rich vein of Ambararatakely is located 30 km south-west of Tsaratan…na on a rolling slope below Mt Bejofo. The quartz-gold vein is rich in tourmaline and it has been exploited in the past, like other deposits of the region, by the Syndacat Lyonnais, mainly by monitoring away the gold-rich topsoil. The area is strongly lateritised, and some modern test work of these laterites would seem warranted (IMR's opinion).
  
 Ambolosikely

The deposits occurs 30 km south of Tsaratanana in several quartz veins. The main orebody is a subvertical lens with thickness of 0.5 - 0.75 m. and striking at least 30 m. Among the accessory minerals there are actinolite-tremolite, chalcopyrite, azurite, pyrite, and native bismuth; the gold fineness ranges between 750-800, possibly indicating the presence of lead silver sulphides (IMR's opinion).

 Analanava 

This prospect is in three quartz veins of which the most important, well interstratified in the schists, is about one metre thick. Chalcopyrite and baryte are accessory minerals. Apparently, only one vein has been exploited (Besairie, 1966, p272a).

Anatitsimaraimbo

This prospect occurs 30 km south-west of Tsaratanana in close stockwork of small quartz veins only few centimetres thick. In some of them gold is directly visible to the naked eye. This mineralisation seems of the "dissemination" type.

MAEVATANANA GOLD DISTRICT



Location and history

The Maevatanana gold district is immediately to the west of Tsaratanana. The town of Maevatanana (comfortable hotel, telecommunications, no airport) is central to the goldfield and can be reached by 330 km of good, surfaced road from Antananarivo (sketch 7/14).

Maevatanana was the goldfield where the first concession to foreigners was granted by the Malagasy government: to Mr Suberbie in 1886. The centre of these exploitations was at Suberbieville, which is now the town of Maevatanana.

The first systematic exploration of Suberbie's vast concession started in 1888 and was carried out by competent personnel including several mining engineers.

A dozen small mines were operative by 1891. The first hard rock mine started on a large concordant vein, with a thickness of 2.5 m with visible gold at Nandrojia, 1 km south of Maevatanana. In 1891 a plant was installed with mill and amalgamation tables. Power was provided by two turbines of 80 CV on the Ikopa River (sketch 7/7).

In 1909 the Nandrojia vein was exploited by pits and cross-cuts but the operation was uneconomic and was abandoned. The alluvions and the eluvions were then providing the largest part of the production which reached 658 kgs (21,200 oz) in 1909. Gold production then decreased rapidly, particularly after the start of WWI.

Maevatanana's gold production was largely due to the efforts of Mr Suberbie and then by the "Compagnie Occidentale", later to become the "Compagnie Franco-Malagache". There is no record of the gold grades worked by these companies.

In 1914 attention was focused on the Ikopa black sands and the gold-bearing laterites. A small hydroelectric plant was built on the Antafofo waterfalls of the Ikopa (sketch 7/7) and a relative powerline. At least one work at Betaimby was equipped with monitors.

This large plant had only a limited life, and ended in total failure (Besairie, p 272b). Slightly later two dredges were brought on the Ikopa, one of them at Antafofo waterfalls (see sketch 7/7). Not surprisingly for the time, these dredges could not work properly as the Ikopa has very irregular bedrock. It would be interesting to see how modern small suction dredges, let's say a Keene with between a 2" and 6" suction head, would preform today in the same region.

In 1921 rumours started about the extreme richness of the laterites of Tainangidina and of Ranomandry. A sober Mines Department Service downplayed expectations and carried out a survey, which although insufficient by modern standards, did not show serious resources (at the time; but in view of the successful lateritic gold deposit of Boddington in Western Australia a re-evaluation of Maevantanana laterites is well warranted - IMR's opinion).

From 1929 the "Compagnie Franco-Malgache" devoted itself exclusively to the artisanal mining (orpaillage). Before WWII seasonal dams were built to dry various sections of the Ikopa over a length of 30 km which assured a good production. At least seven such barrages are recorded (sketch 7/7). These workings started anew in 1949 at Bekaprija but were again abandoned in 1951.
  
Geology

Maevatanana goldfield is underlain by the systems of Graphite and Vohibory. The gold originates essentially from magnetiferous  quartzites. The most productive district has been defined by the polygone between the Ikopa R. the Menavava R. and the Betsiboka R. (see sketch 7/7), or an area of about 7,500 km2, where at least 44 gold occurrences have been recorded (Besairie, 1966). In this area gold was exploited mainly in alluvions but also by crushing the exposed quartz veins at their contact with laterite.

Alluvial exploitations had been the most economic, but any attempt to mechanize them failed and only "artisanal" mining managed to survive.

In the case of the "black sands" the gold occurs as inclusions into the magnetite, showing the importance of magnetite-rich sandstones as the primary source of the alluvial deposits. As a consequence, the richest alluvial basins are the ones where the exposures on magnetite-rich sandstones are most abundant: the Ikopa Basin with its tributaries Nandrojia, Belambo, Mandraty, and Firingalava, and the basin of Kamoro with Tsiandrarafa, Aneriga and Bejofo.

The alluvial terraces, especially in the Ikopa basin, were never considered important as they had grades inadequate in relation with the thickness of the overburden. These terraces were seldom exploited, and then only by pits. A modern re-evaluation taking in account present economic ore grades and modern, low-cost stripping techniques coupled with efficient magnetic separation, seems warranted for the Maevatanana gold district. (IMR's opinion)

We note that Maevatanana is one of the districts where amalgamation was most extensivily used; most probably without any retorting and recovering of the mercury. A study of the present environmental conditions of the district would seem highly desirable.

Table 6 lists no less than 43 recorded deposits for the Maevatanana gold district, most of them alluvial.

Below are listed some of the more interesting gold occurrences of the district.

 Individual Deposits

 Betaimby

This prospect occurs 50 km south of Maevatanana and 2 km east of the Ikopa River. It is a very old prospect, exploited since 1888, and which consists of numerous veinlets of gold bearing quartz distributed in small pockets along the same plan ("en chapelet") in the lateritised gneiss.

Starting in 1914 these laterites were worked by monitors and sluices. Gold was recovered by amalgamation. A hydroelectric plant was installed at Antafofo on the Ikopa River utilising a fall of 17 m and generating 200 CV and a 7 km powerline to join it to Betaimby. The failure of this venture has been total: 20,000 m3 of laterite produced only 1,146 gr Au, or a grade of 0.06 gr/m3. Available records do not mention which type of plant was used nor what gold recovery has been achieved.
  
 Nandroja  

Only 1 km south of Maevatanana, this prospect was the first hard-rock exploitation by Mr Suberbie. A conformable quartz vein 2.5 metres thick was worked at the surface over 40 m and then exploited underground in pits and cross-cuts. The quartz was milled. These works became uneconomic in 1910 and were stopped the same year.

 Ranomandry

In the Ranomandry sector, 30 km south of Maevatan…na, several gold prospects occur between the villages of Bejofo and Betanimanga. It has been suggested that these prospects consist in a single, continuous vein; this is debatable.
There was a reconnaissance in 1928 over the old superficial works of Betanimanga. The 73 samples collected gave an average grade of 18.6 g/t Au. An amalgamation test over two tonnes of quartz has given a grade of 29.4 g/t Au. In 1928 the underground workings  consisted of: an incline of 34 m, a cross-cut of 80 m and two galleries of 50 m. These workings have not been followed. 
  
 Tainangidina

Much has been said about this deposit, situated 25 km south-east of Maevatanana (sketch 7/7), both for its vein and laterite potential.

The first study was carried out in 1915; others in 1923 and 1927. The deposit occurs in gently rolling hills and consists of eight gold-bearing quartz veins concordant with the gneiss of the Vohibory system. The eight veins cover a width of 200 m. A ninth vein is about 100 m away from the main system. The average thickness of the veins is 30 cm and their length is between 50 and 150 m with the exception of one that strikes 650 m.

The average ore grade worked was around 18 g/t Au. All these veins, dipping 60§, are apparently exploitable to a depth 100-200 m and one of them to 300 m, but this figure seem implausible (IMR's opinion). A cross-cut 320 m long intersects the vein swarm. On this basis a tonnage of 200,000 tonnes of quartz would be equivalent to almost 4 tonnes of gold (Besairie, 1966 p273b).

However, these calculations result from rather risky extrapolations without systematic sampling and no proof that the ore grades extend at depth. In other words, the prospect has been considered a proper single vein deposit rather than a system of veins with large variation in grades and continuity.

Resource estimates of the Tainangidina hill's laterites appear to be limited, contrary to previous hopes. Also, the grades are rather low with the exception of the vicinity of the gold-bearing quartz veins. All organised work on Tainangidina stopped in 1928.
  
 Ikopa sands   

The Ikopa river bed is unquestionably gold-rich but its exploitation is difficult. The river is deep and the current strong. The river bed is irregular with boulders, channels and scours. An attempt with two dredges in 1917 ended up in failure. Particularly galling was the fact that the rainy season invariably destroyed the river dams and that work was possible only in the dry season.

Between 1930 and 1944 certain sectors of the Ikopa, Mandarti and Belambo rivers were dried by means of dams and derivation channels. This technique permitted the exploitation of the dried sectors for 2-3 months a year. The same barrages were built anew after one or two years and they provided about 50 kg/year of gold. Sketch 7/7 shows some of the largest dams built on the Ikopa.

The last effort on the Ikopa River was made at Bekapirijy where a small rocky island favoured the construction of a dam. This was followed by digging, on the western shore, a long derivation channel and the exposure of the river-bed for a significant distance. This project, possibly the largest ever established on the Ikopa River, worked intermittently between 1949 and 1951 with a meagre recorded production of 7.1 kg of gold. No further barrages have been built on the Ikopa although some other attempts have been made with suction dredges in recent times.

BETSIRIRY GOLD DISTRICT


 Location and History

The Betsiriry gold district is located to the extreme west of Madagascar's crystalline Basement (sketch 7/14) between 19§ and 20§ latitude south and 45§ to 30' longitude. The town of Miandrivazo (airport, telecommunications, small hotel) can be reached by 250 km of good, surfaced road from Antsirabe or directly by plane from Antananarivo (sketch 7/14).

This gold district produced 2.5 t (80,000 oz) of gold between 1901 and 1921. The greater production took place between 1903-1914 with a peak production of 205 kg of gold in 1910.  As usual, attempts to dredge the major rivers of the district ended in failure. In particular, an English company built a plant which collapsed before reaching the Mahajilo Falls where it was supposed to operate.

 Geology
The BRGM indicates this goldfield as being Proterozoic in age and so as not to complicate the issue this has been maintained in sketch 7/2 of the present report. In reality this assumption does not seem adequately supported. Besairie (1964, Feuille du Centre) put these gold mineralisations firmly in the Amborompotsy Group of the Vohibory system. Hottin (1972) proposes an age between 1,700 and 2,000 MA for these lithologies. On the basis of available information the Betsitiry gold district does not look significantly different to the great majority of the Madagascar's other gold mineralisations which are considered of Archean age. The only distinctive character of the Betsiriry gold district is that the known gold mineralisations appear to be located in the "migmatitic front" or in the passage zone between the gneiss and the epimetamorphic series "schist-quartz-limestone". In a radius of 50 km from Miandrivazo at least 14 gold occurrences are reported (Besairie, 1969, Feuille 5). These prospects occur in gneiss and migmatites and they appear unrelated to later intrusions. 

The mineralisation is in free milling quartz often associated with magnetite and iron and copper sulphides. In some deposits (Ankaboka) part of the gold is syncrystallized with the magnetite. In others (Antasaily) gold is associated with mispickel.

The Betsiriry gold district may be considerably larger than indicated in past reports. We note several gold prospects: Ankofoka, Antsiroroka, Antsevakely, Miandrarivo, almost 100 km north-east of Miandrivazo district in what is essentially the same geological environment.
There is evidence that recent prospecting by "artisanal" miners has further extended the
boundaries of the Betsiriry gold district (sketch 7/1).
Table 6 lists only eight recorded deposits for the area is still little known. Significantly, all
of them are primary.

 Individual gold deposits

 Dabolova

Among the most important deposits of the Betsiriry goldfield is the Dabolova Group, 30 km southeast of Miandrizazo, which has been in continual exploitation from 1885 to at least 1966 (Besairie, 1966).
The quartz vein of Takodara I striking 2 km has been exploited over all its length. The recorded grade varied between 10 and 50 gr/t Au. At Ambohipisaka, there are there are four main veins, very irregular and in separate, lens-shaped gold-quartz occurrences ("en chapelet").

An exploitation of Dabolova was attempted between 1937 and 1939 with crushers, mills and amalgamation tables. In 1938, 200 t of quartz yielded 2.8 kg of gold indicating a minimum grade of about 14 g/t Au. We note that the plant was not equipped for the treatment of auriferous pyrites. This may account for the low gold recovery (IMR's opinion).

Other prospects of Betsiriry goldfield still artisanally worked in 1966 were Analabe, Ankarongana, Kiranomena, Antasaily and Andisiavo.

ITASY GOLD DISTRICT

Location and History

The gold district of Itasy-Tsiroanomandidy is located 50-150 km west of the capital, Antananarivo, and produced 1,260 kg of gold between 1901 and 1921. Numerous vein deposits were worked and rapidly abandoned. Its peak production was in 1904 with 174 kg produced, largely from the Vohinambo deposit.

The Itasy gold district is a rather diffuse one, without a distinct geographical expression. The village of Analavory (telecommunications, small hotel, emergency landing strip) can be reached from Antananarivo by 124 km of good surfaced road (sketch 7/13). From this village most of the gold prospects of the Itasy can be visited. The use of a 4WD vehicle is advisable.

 Geology

There is relatively little geological information on the Itasy gold district and practically no deposits marked even on the 1:500,000 geological maps. The district can be seen as the western extension of the Ambositra-Antananarivo gold district.

The gold occurrences occur in the migmatites, gneiss (often garnet and sillimanite bearing), quartzites and micaschists. All the gold prospects occur in the graphite-rich zones of the Archean Graphite System. Granitic intrusions are frequent in the region but are unfortunately undated. Some gold deposits seem controlled by the strong N-S and E-W tectonics of the area (see Plate 2 in the present Database).

The quaternary basalts that form the Itasy massif itself are  unrelated to the gold mineralisations.

Throughout the district there are several mentions of auriferous quartzites with magnetite: i.e. Ambohimanoa, Ambohitsivalana, Behana. These are potentially large if low-grade deposits very amenable to modern extraction techniques, particularly if the gold occurs (as has been indicated) as inclusions in the magnetite. IMR is of the opinion that this is well worth investigating.

Besairie (1966) lists 13 gold deposits occurring in a large arc between Ambatolampy and the Itasy (see also Table 6); all primary. These deposits are described below:

Individual deposits

Ankadivoribe (Ankopakely)

The prospect is located at only 9 km to the south of Tananarive. It is a very old prospect in several small veins of gold-bearing quartz in migmatites, gneiss and granites. The prospect has been worked by a large trench producing between 1-2 kg gold per year.

Vohiambo

This deposit is located 10 km south-west of Arivonimamo. The deposit was discovered by Mr Talbot in 1904 who extracted 70 kg of gold in a few months. Once again the deposit consisted in series of gold-bearing quartz veinlets of modest thickness interstratified into the gneiss. The mineralisation is enriched at the contact with the overlying laterites. The occurrence has been exploited on a trench of 80 m strike and 25 m depth and then by underground works. These works, poorly executed, caved in and the deposit was abandoned.

Ambohimanoa

20 km north-west of Tananarivo this deposit consists of a large quartzite lens in sillimanite-rich lithologies. No quartz-gold vein as such has been recognised. Basairie considers this mineralisation of a "disseminated" type; it certainly looks anomalous compared to the prevalent style of gold deposits in Madagascar.

A sampling program, presumably carried out in the 1960s on the old working and consisting of 60 m of channel sampling, produced five samples out of eight with grades between 1,5-2 g/t (by amalgamation). The crushing of the other samples to 100 mesh did not indicate gold. Along the hillsides quartzites have long been worked in the past by long hand-dug channels ("lakantany" in Malagasy) which drained auriferous eluvions during the rainy season. On the hillside there is an alluvial terrace which, in the past, has been exploited in its richest parts.

It is obvious that Ambohimanoa has been worked only with very crude artisanal methods; given the mentioned "disseminated" nature of gold deposits in sedimentary formations a modern quantification of the Ambohinamonoa prospect is well warranted (IMR's opinion).
  
Antosalobato

This prospect occurs 20 km south of Arivonimamo village. Its old working date is around 1912. A gully-dissected hill is the likely source of the gold in the Antosalobato creek. A bed of mica-gneiss about 15 m thick hosts abundant quartz-gold veinlets concordant with the gneiss foliation and dipping 60 degrees N. The largest vein, about 1.2 m thick, showed visible gold over 10-15 cm. Pyrite is also present. Underground works have failed to find extensions of this deposit.
  
Ankafotra  

This prospect occurs 50 km to the west of the Tsironomandidy village. Its placers were recognised at the start of the century. Two hills, Ankafotra and, above all, Betanimena, show a substratum of auriferous gneiss. Where these have been lateritised they formed local concentrations of very fine gold, with occasional outcrops of auriferous quartz veinlets. In the alluvions of the Ankafotra and Bekopaka rivers gold can occur as pepites (suggesting a goldfield where gold detectors could be usefully employed by individual miners). The forested areas of these alluvions have not been worked.
  
Antanifotsy

This prospect, located 40 km south-south-east of Tananarive, consists of altered and lateritised gneiss with veinlets of auriferous quartz. The occurrence has been prospected over a 2 km strike with trenches of various depth. These works are very old and probably date to the end of the last century. Underground works were carried out in 1910-12; there is no record of the results.

Ambohitsivalana

A prospect 35 km to the east of Tsiroanomandidy village. The placers were recognised at the beginning of this century.  Some early exploitation produced about 50 kg Au before 1895. Two quartz veins 40-80 cm thick strike over 200 m and have been literally riddled with shafts of 12-15 m depth.

The quartz was artisanally crushed ("pillonn‚") and washed. The auriferous veins seem to disappear immediately outside the worked zone. Underground works have not been successful. Nearby there is quartzite with weakly auriferous magnetite which has formed low grade alluvial deposits. Gold recovery has been attempted with shaking tables. No mention of modern exploitation by wet magnetic separator (IMR's observation).
  
 Behana

A prospect 65 km east of Tsiroanomandidy. There is an old alluvial exploitation in a zone with magnetiferous quartzite and amphibolites.
  
Tsimbolovolo

This prospect lies 52 km to the north-west of Tsiroanomandidy village and was exploited even before 1895. Two placers of 1,800 x 800 m and 1,500 x 100 m produced 387 kg of gold between 1903 and 1909. Production then fell rapidly. The prospect occurs around the Betanimena hill which consists of amphibolites, gneiss, micaschist and, once again, magnetiferous quartzite.

The amphibolites, largely formed by the cummingtonite-grunerite series, enclose a layer of kyanite (disthene) with visible gold. The magnetiferous quartzites are auriferous and at times show visible gold. Both eluvions and alluvions have been long exploited. Some essays by sluice between 1909 and 1910 have been rather unsatisfactory with yields of about 1 kg Au a month. The exploitation mainly took place by the Malagasy method of "lakantay".

AMBOSITRA-ANTANANARIVO GOLD DISTRICT

  
Location and history

The Ambositra-Antananarivo gold district is particularly developed in the province of Antsirabe
and officially produced 1,489 kg (48,000 oz.) between 1901 and 1921. The largest part of this
production came from the region south of the Onive River (sketch 7/8). Some deposits occurred around Ambatolampy and in the Faratsilho sector.

Gold production was particularly important from 1890, when the exploitation was carried out by
administrative corve‚s. Around 1900 these corve‚s employed more than 2,000 workers in the
Sarobaratra River alone. The inevitable exhaustion of the alluvial resources took place
immediately afterwards and was a powerful incentive to the first exploitation of primary gold,
particularly where their contacts with the overlying laterites formed zones of strong enrichment.

This gave the district a new lease of life with a high production between 1904 and 1911. At that time numerous exploitation of graphite were developed and attracted labour away from the less lucrative gold workings. Production has been totally artisanal ever since.

It would be futile to list all the deposits that occur in the Ambositra-Antananarivo goldfield.
In any case records are very scarce, and they are mainly known by traces on ancient workings
(Besairie, 1966, p 276).

The heart of this goldfield can easily be reached by 100-180 km of excellent surfaced road from Tananarive (sketch 7/15); most individual deposits can be reached only by 4WD vehicles, particularly during the rainy season. The town of Antsirabe offers very good and pleasant accommodation.

Geology

Once again the gold mineralisation of Ambositra-Antananarivo is hosted in migmatites, gneiss and micaschists of the Ambatolampy group, Graphite System (see Plate 1), containing quartz-gold veinlets with secondary alluvions and eluvions.

The largest part of these deposits is within the zones of micaschists or micaschist-gneiss but
they appear little affected by the migmatisation. On a regional scale gold seems to be
distributed on the migmatisation front.

Leucogranitic intrusions are common in the area but their relationship to the gold
mineralisation, if any, is unknown.

The regional tectonic is essentially N-S and E-W and some deposits appear fault controlled.

Sketch 7/8 shows some of the most notable workings of the south Onive district over an area of approximately 700 km2. Besairie (1966) mentions at least five underground workings (Analasarotra, Andranofito I and II, Ankanona, Miakatso), but there have certainly been many more.

The primary deposits of Andranofito, Tongarivo and Soavinarivo consist of concordant quartz
veins, locally rich and rapidly lost at depth where they reportedly had uneconomic grades (but at the time, grades below 10 g/t in hard rock were considered uneconomic). Below are given some details of the last deposits to be worked in the region.

Table 6 lists 39 recorded deposits for the Ambositra-Antananarivo gold district. About half of
them are primary.

 Individual deposits (Antisarabe region)

Tsinjoarivo

Gold was exploited on the Onive River in the dry season, in particular downstream of the
Tsinjoarivo. Some projects, utilising sand-pumps, had been planned but were never carried out. An attempt to dredge downstream of Antanifotsy failed.

Sarobatara

The mount Sarobatra (1,867 m  a.s.l.) is the highest point of a  topographic range 25 km long
which terminates at the Onive River,  north west of Tsinjoarivo village (Sketch 7/8). The gold
workings, very old, were developed on the Sarobatra River and its tributaries: the creeks Analava and Anteritery. The alluvions were very well developed with thicknesses of between 2 and 4 metres.

The grade was initially rather high, reaching 4 - 5 gr/m3. These alluvions extended about 200 m. The entire length of the wide valley of Sarobatra has been worked. It was the best alluvial
deposit in the region. The latest alluvial exploitations were developed on Miakatso and Besorohitra creeks to the east of Antofimbato; Ambodiala, Laptsihazo, Antanetibe and Saovinandriana to the east of the range; the creeks Analalava and Anterivody to the south-west and Antasahondra to the south. The last works took place at Ambohimanga (1,500 m north-east of Sarobatra) and Antanetibe (3 km to the south-east). In 1969 there still was production from Antsofimbato, described below.

Antsofimbato      

This prospect lies on the north-east extension of Sarobatra; the old workings of Antsofimbato in the 1950s attracted attention because the continuity of its production: more than 1 kg gold a
year. Here is the synopsis by Besairie (1966, p 276b) of some investigation carried out in 1961:

"The formation worked consists of a bed of heavily lateritised micaschists, about 20m thick,
resting with a dip of 45§ over the quartzite which is the backbone of the mountain range. These micaschists enclose several concordant quartz veinlets striking about 100 m and mineralised over a thickness of 50 cm.
These veinlets are not continuous but rather in separate little lens-like pockets ('en chapelet'=
rosary-like) over a width of about 10 m in the micaschists. Gold is sometime visible to the naked eye but more often is only visible after crushing and washing the quartz.
The micaschists contain traces of gold, very fine and very dispersed, with no [apparent] economic grades. The rich zone has been exploited by trenches and some minor underground working. A 1960s study by BRGM concluded that the grades were insufficient for mechanised exploitation of the deposit."

 Andravoravo 

This abandoned gold prospect is located 30 km south-east of Ambatolampy in a series of graphitic mica-schists. The prospect was examined in the 1960s by BRGM personnel (Besairie, 1966, p 277a).
The principal bed, exploited over 1 km, consists of a level of mica-schists very rich in
sillimanite (local name = vatodidy) with an average thickness of 50 cm, intercalated between
quartzites on the footwall and a graphite-bearing layer on the hanging wall.

The deposit has been entirely exploited in its eluvial and alluvial parts and also in the
sillimanite-rich part more readily accessible by trenches. Channel samples in the
sillimanite-rich part of this prospect have indicated gold grades from 1 to 5 gr/t.  We ignore
the analytical techniques for these determinations: probably nothing more that hand-crushing the quartz followed by washing it with a gold-pan (IMR's opinion).

 Ialatsara

This gold prospect occurs 24 km west and slightly south of Tsinjoarivo. Its exploitation started
in 1889 by Mr Savaron - then one of the first legal French exploitations in Madagascar.

All the creeks running from the hills were more or less auriferous. To its south-west the deposit
was worked at the beginning of the century by Anasaha. Thick, bluish, quartz veins concordant
with the mica schists' foliation were the gold source: the gold generally being present in
association with pyrite. Unfortunately these veins were very discontinuous. The Belanitra,
Antkitsika and the Andranomiady rivers have been worked for alluvial gold.


Andranofito



This gold prospect occurs 9 km south of the Ambatomiady village and it is important both for its alluvions and its underground workings - at least two of them (see sketch 7/8). Once again the gold occurs in numerous quartz veins in the micaschists. The most important workings are around the topographic peak of Andranofito with over 379 m of underground working. But the main vein, with visible gold, was worked in a very rudimentary way, with crowbars.



Soavinarivo

A prospect 31 km ESE of Antisarabe. This deposit was the first to be worked underground in the region. The prospect consists of a vein of gold-bearing pyritic quartz which has been exploited by superficial workings over a length of 300 m.

A 25 m shaft was sunk to exploit the prospect at depth but was abandoned because of water
difficulties. The workings were abandoned in 1911. There are no records about ore grades. As the ore was very rich in pyrite, a small plant for the crushing and washing of the pyrites was
installed. After the first recovery of the gold by panning, the residual pyrite was chemically
treated by the Chemical Laboratory of [Antananarivo's] Mines Service.


Tongarivo

A gold prospect 12 km east of Antisarabe. Three quartz veins were worked both om the surface and underground. Once again, all activities ceased in 1911.


Kitsambo 

A gold prospect about 20 km north-east of Faratsiho. There are important underground works in the sectors of Faravoitra and above all at Antanifotsy. The gold is found as inclusions in the gneiss and these have been exploited particularly along alteration [lateratization] zones. But the main production came from alluvial deposits.


 Ianamalaza

A gold prospect 45 km WSW of Antisirabe, on the upper course of the Isakelo River: a tributary of the Mania River. The ancient workings extended over several km in the valley. A quartz vein with visible gold has been totally mined out.

   Individual deposits (Ambositra region)

Antezambato

A gold prospect 18 km south of Ambositra in the upper valley of the Ivato River, the prospect
showing important old workings. Two large trenches, one 400 m in length (probably visible in
Satellite images - note of IMR) were made to exploit an auriferous level, now partially covered
by slides, in the migmatites: probably the gold mineralisation was hosted in quartz veinlets as
this is the regional pattern. This occurrence has given place to important eluvial deposits and
to a mineralised [fluvial] terrace now totally exploited.


Itea (Also Rare earth mineralization)

Itea is a rather different deposit from most of the region. It occurs 50 km to the south-east of
Ambositra (sketch 7/8/1). Its position is well to the west of the main Ambositra-Antananarivo
goldfield. Also, while the majority of the gold occurrences of this goldfield are in the
micaschists and the graphitic gneiss of the Ambatolampy Group of the "Graphite System", Itea gold prospect is apparently hosted in the granite of Vavavato-Antofinandrahana which Besairie (1964) estimates to be 700-1100 MA in age.

The Itea area is heavily mineralised with copper, lead and bastnaesite. Pegmatites are also
frequent in the area (quartz, beryl) and a few have been mined (i.e. Tambolehibe). The strike of
the pegmatites and some major faults in the region is N 40§E. It would seem that this fault has
at least partially controlled the Itea prospect.

The mineralisation apparently consists of gold impregnations into the micaschist and the

quartzite but also some alluvions. Itea's primary mineralisation was about 7 m thick and has been worked underground, probably not below the water table, at about 22 m from the surface.

BRGM investigated Itea in the 1960s but the works were not apparently followed up and very little is presently known of this prospect beside the poorly-drawn section given in sketch 7/9.

Given the anomalous nature of Itea's mineralisation a detailed and modern investigation of this
deposit seems well warranted.

VOHILAVA-AMPASARY GOLD FIELD (MANANJARY)



  
Location and History

This goldfield is often referred to in literature (ie. Besairie, 1966) as the Mananjary
goldfield. It has been one of the major producers in Madagascar with a recorded production of
8,580 t (276,800 oz) of gold between 1901 and 1921: an impressive performance.

There are no records of this goldfield producing before 1901 but at that date it was producing in excess of 500 kg/y (16,100 oz) or about half of all Malagasy production at the time. Misguided French investors and administrators (Gallieni, 1990) were at the time pinpointing this goldfield as a potential rival of Witwatersrand in Transvaal. An entirely different geology of the two goldfields rapidly disproved these wild expectations.

The gold exploitation of this goldfield was particularly intense until World War I with a peak of
744 kg/y of gold in 1903. It decreased sharply immediately after, particularly when coffee
plantations over the old gold alluvions proved more economic that artisanal mining.
  
The goldfield occurs around the pleasant coastal city of Mananjary, 350 km south of the main port of Toamasina (ex Tamatave) on the Madagascar east coast - see sketch 7/15. Mananjary
(telecommunications, airport, hotel) can be conveniently reached from Antananarivo by commercial flights with Air Madagascar's "twin otter" planes.


 Geology

The Vohilava-Ampasary gold district is underlined by the gneiss and migmatites of the Mananjary Group of the Vohibory system (Besairie 1964) and dated at 2,150 MA (Pb/Pb method). This group is equivalent to the Ambatolampy Group in central Madagascar. Intrusive in the Mananjary migmatites is the biotitic-monzonitic granite of Befody (see sketch 7/10). 

In this region of Madagascar the Vohibory system is rather different from the rest of the island.
It can be split up into three sections: the Maha group in the east (sericite and chlorite-rich
schistes affected by a tectonic zones with tight folds, faults and mylonite zones), the Vohilava
group in the centre (mica-schists and geisses), and to the the west the Ifinadiana group
(closely-folded migmatites). Throughout the region there are numerous, small intrusions of
ultramafics.

The impression that at least some of the Vohilava-Ampasary gold occurrences can be hosted in what an Anglo-Saxon geologist would call greenstone belts cannot be be dismissed. Hottin (1972) seems to suggest this possibility.

Geochronological determinations have given an age of 2,140 MA for gold-sulphide mineralisations (Andrambo) and two possibilities close to 900 MA for a second mineralisation cycle: 890 MA for the zircons of the Namolika granite to the extreme south of Befody massif (Pb/Pb), and 850 MA for the alluvial monazite of Mananjary (Pb/Pb) (Besairie, 1966).

It would therefore seem that an age of around 850 MA can be safely suggested for the Befody
granite: this is in good accord with the general period of granitisation and charnockitisation of
Madagascar and peninsular India (See Plate 1 and sketch 6/3).

Sketch 7/10 shows the distribution of the known gold deposits of the Vohilava-Ampasary district. We note to the west of Befody granite the auriferous zone Ampasary-Sakaleona, and to the east the zone "de la Petite Falaise", and still further east the region Saka-Maha-Sahandrambo - essentially alluvial.

The primary gold mineralisations are geologically controlled: they  are all below the magmatitic
front. In Ampasary-Sakaleona region the gold mineralisation is localised in quartz veins at the
contact between gneiss and the lenses of ultrabasics included in the gneiss. On the "Petite
Falaise", the gold occurrences are localised at the contact between granite and crystalline
schists. The auriferous quartz veins occur in both lithologies but generally at less than 100 m
from the contact. Significantly, all the creeks running across this contact are more or less
auriferous.

In the case of the Maha and Sahandrambo rivers the gold deposits are over large fault zones and it is plausible that there is a correlation between these fault zones and gold mineralisations, both primary and secondary. Some primary gold deposits occur as far as 30 km away from the known surface expression of the Befody granite (sketch 7/10). 

One of the characteristics of the region is the abundance of quartz and sulphide veins. Their
thickness varies from 0.2 to 1 m, and it is generally largest in the faulted zones. The
mineralisation consists of gold, pyrite and mispickel [arsenopyrite] commons.

Chalcopyrite and galena are rare and in variable proportions. Tourmaline and muscovite are
common. Some pegmatites are gold-bearing although this can probably be dismissed as an
unimportant remobilisation episode during the Pan-African event (480-550 MA. A major proportion of the gold occurs as inclusion in sulphides.

From about 100 samples collected in a study carried out in 1952, all proved to be auriferous but with grades at or below 0.5 g/t Au (Besairie, 1966); but the gold seems to be ubiquitous.

The regional morphology is important in the control of the placers. In the sharply cut valley the
rivers tend to have a torrential regimen. The alluvions are therefore very irregular and the gold
distribution is controlled mostly by the bedrock's shape and nature.

The evolution of the relief has given place to several ancient terraces, the oldest only 20 m
below the thalwegs. The surface of the alluvions is, in the majority of cases, smaller than 10
hectares and it reaches 50 hectares in very few cases. Larger deposits do exist along the Saka and Maha rivers but their exploitation proved to be difficult.

In the region there is a secondary hydrographic network formed by small water courses of modest importance but with frequent alluvial terraces. The placers of these tributary rivers have been practically exhausted. The placers of the main river system have been exploited wherever accessible by a shovel. The old river terraces, more or less at water table height during the dry season, are covered by fine alluvions 5-8 m thick. These terraces have rarely been exploited. Furthermore, they are now overgrown by coffee plantations.

In most of the auriferous alluvions of the Vohilava-Ampasary goldfield the gold-bearing pebble
horizon is covered by 3-5 m of fine alluvions and lateritic clays. But, in spite of this,
overburden exploitation is easy if water is readily available. Most of the richest terraces have
already been exploited.

The grades in the alluvions range from 1 to 2 g/m3 but exceptionally can reach 3 - 4 g/m3. The
thickness of the auriferous conglomerate varies between 0.5 and 2 m. The average grade for the terraces still unexploited (1966) is around 1 g/m3 or less.

The gold recovered is generally coarse. Pepites are rare and of small dimensions. The gold
fineness never goes below 945 and occasionally reaches 995.

In the following chapter we will describe several gold deposits, mostly, but not all, from
Besairie (1966). Only a few of these deposits have been studied in any detail. It is these
mineralisations that - regardless of their grades - fed the secondary deposits, either alluvial
or eluvial, and these have produced most of the gold in the region.

Table 6 lists a record number of 58 known deposits for the Vohilava-Ampasary gold district.
Significantly, 27 of them are primary.

 Individual Deposits


Ampasary            

The small area of the Ampasary River (see sketches 7/10 and 7/11),  70 km north-west of
Mananjary, is the second biggest gold producing area in Madagascar, immediately after the
Andavakoera. The Ampasary course is sinuous and interrupted by numerous rapids. Important
auriferous terraces are developed around it in major meanders (sketch 7/12). On the east of the river, on the hilly slopes, several prospections for hard-rock gold have been carried out with
success. But obviously this has been an under-explored target.

The richest zone starts to the south with the placers of Hanning and Betampona which have
produced respectively 119 and 132 kg of gold. More to the north Malazamasina and Alexander have produced respectively 55 and 195 kg of gold: some terraces and flats in this area have not been exploited due to heavy forestation.

Further north there are the placers of Antanbao which have produced 367 kg of gold: this section of the river consists of a succession of rapids and deep pans where the exploitation was carried out by diving ("alorano", in local parlance). A series of alluvial terraces occur on both sides of the river: the richest have already been exploited.

Given the chaotic way of the old workings is difficult to estimate how much gold could still be
won from the Ampasary River but several meanders are certainly still very rich. The Ampasary
River ends with the sectors of d'Ambalavia and Ambodiara which produced 125 kg of gold. The auriferous zone extends to the north with the basins of the Sakaelona.

Several primary gold deposits are known on the eastern shore of the Ampasary. They have been exploited only by very primitive means, without the use of compressors or explosives and they have been quickly abandoned at the first difficulty. Among these primary deposits we can quote Ambalakaza-north, Tobilava, Antanasy and Antanambao-east and Ambalavia-Ambatomainty.

All these works were in gold and sulphide-bearing quartz veins in amphibolite and tremolite
schists. It would be interesting but probably near impossible to locate these old workings after
more than 80 years. The region and the style of mineralisation is rather favourable to regional
exploration by modern geochemistry: initially by stream sampling followed by grid soil sampling on anomalous zones (IMR's opinion).

Sakaleona

The Sakaleona River and its tributaries (Sahanana, Andranomanjaka, Tsaravinany, Nandravaona, Tembinah and Sahakoriana (Besairie, 1966 p 279b) have yielded more than 500 kg of gold. See sketch 7/10 for a general view of the area. Obviously, the geological setting is very similar to the Ampasary goldfield and all gold mineralisations originate from the contact between the Befody granite and the enclosing gneiss and micaschists.


 La Petite Falaise

This series of deposits occurs along the eastern contact of Befody granite. Some individual
deposits are described below.

 Bebasy

At Bebasy, 12 km south of Soavina village, a vein in the sericite-schists has been exploited at
the surface over 520 m, and underground for 350 m. The quartz was crushed by a battery with 10 stamps powered by a steam engine. The average ore grade was a respectable 13.5 g/t Au with a gold finesse of 970.

Six km to the south the vein of Sahafandroana, another quartz vein, yielded gold grades superior to Babasy but it was worked very little and prospected only by a trench of about 100 m in length.
In the same sector to the west of the Ambodilafa village there are other primary exploitations:
Ambavalero and Ambohitsara. The same sector also hosts several auriferous alluvions, particularly along the tributaries of Sahavato: Sahafandroana, Sakandrekata, Sakafotsy Sahafanana and Ankelakambo.

Andrambo-Maroantovo

Perhaps the most important primary gold deposit of the region is Andrambo-Maroantovo, 40 km to the SSW of Soavina village. The deposit consists, as usual, of a lens-like quartz veins
concordant with the Mananjary gneiss. These gneiss are often dioritic and have lenses of
soapstone.

The deposit is well within the surface expression of the Befody granite (sketch 7/10). Galena
from this vein has been dated at 2,140 MA. The main vein strikes N 140§ and dips 70§ to 80§ with an average thickness of only 20 cm; this vein has been followed on strike for about 4 km by artisanal miners who have exploited only the richest sectors, with reported grades of 30-80 g/t Au and even higher (Besairie, 1966, p 280b).

The southern sector of the vein is the better studied and the richest. BRGM reports an average
ore grade of 50 g/t. This sector has been worked over a strike of 1,400 m with trenches, adits
and cross-cuts. These workings were directed only to the zone above the water table.

In 1932 the conclusions from this exploration activities were: very erratic grades, average vein
thickness of about 15 cm, average grade of 20-30 g/t Au inversely proportional to the thickness, gold finesse about 800 with a strong proportion of silver and some bismuth.

Above the water table the vein is enclosed in the laterite and altered gneiss; the presence of a
previous working made exploitation more difficult. 20,000 tonnes of mineralized quartz have been estimated above the water table. There is no consistent information on the vein below the water table, but the grades were thought to be decreasing (no enrichment by secondary alteration) and mining conditions obviously more difficult.

All this did not bode well for a mechanised exploitation (at least in 1932) and no serious
investment took place. On the sector north of the Andrambo-Maroantovo prospect the average vein thickness is larger (20 to 30 cm) but the grade falls to around 15 g/t Au.

Andravoravo-Tsaramiadana

Another recorded primary deposit is Andravoravo-Tsaramiadana which occurs 12 km to the NNW of Vohilava village (see sketch 7/10). Important works were carried out by Mr Hanning around 1910 and were suspended in 1925. It consisted of adits and cross-cuts in laterite. The quartz vein, besides visible gold, contained abundant sulphides with pyrite, chalcopyrite, galena, and mispickel. The vein of Ambodivato slightly more to the north has been exploited in a large quarry.

 Namolika

This prospect occurs to the extreme south-west of the Befody granite, 8 km west of Vohilava
village. The prospect is very close to the granite-micaschists contact which has been explored by adits (Besairie, 1966 p 281a). Nearby, the prospect Lavakianja is noteworthy for its abundance of quartz eluvions.

 Itrozona

To the north of the Vohilava-Ampasary goldfield, the Itrozona River is a tributary of the
Vatovandana which flows into the Indian Ocean to the north of Masomameloka. At Beando, 3 km to the south-east of Beando village, a 40 cm-thick quartz vein has been exploited by a trench 80 m long with a few shafts.

A small 5-stamp mill was installed and operated by a hydraulic wheel. In 1912 this plant produced 36 kg of gold. In the same sector the placers of Androrangapetraka and of Ambodiara have been worked. Other artisanal works took place at the Ambalafary and Sahaberiana rivers.

Sahandriambo

This locality, 18 km north-east of Vohilava, hosts some primary mineralisations in gold-bearing
quartz veins, lateritised and therefore enriched. An open cast mine was opened to exploit
sericite-schists abundantly intruded by quartz-pegmatitic veinlets in a mylonitic zone. There are
records (Besairie, 1966 p 281b) about the presence of quartz-sulphide veinlets up to 40 cm thick with grades of 8 g/t Au and 9 g/t Ag. At Fotobato, 15 km to the NNE of Vohipeno village, there occur large quartz lenses with traces of sulphides: these lenses are very irregularly distributed and they are apparently grading 10 g/t Au.

An abundant sulphide mineralisation is located in the veins near the faulted zone of Andranotonga 12 km to the north of Vohilava.

Some quartz veins with biotite, tourmaline and fine pyrite and mispickel, weakly mineralised in

gold and silver, occur near the falls of the Sahamatrano River on the track
Andranotonga-Tanambao. On the Ambalavary and Ambatoharanana rivers wulfenite (PbMoO4) has been found. The Besonjo creek is noteworthy for abundant quartz with sulphides; but no significant gold values are reported.

Sahandriambo River

On the upper course of the Sahandriambo River fluvial terraces and flats are almost nonexistant and mining took place from the river itself. The actual river bed is certainly very rich as all its southern tributaries are auriferous from the Ambodimanga R. onward.

The placers on the Ambatofotsy R. have produced 76 kg of gold between 1906 and 1928 after being drained by means of a diversion canal 2,200 m long. Around 1910 two meanders upstream of the Antapandrano R. were also drained. These and several other works aimed at tapping the region's unquestionable alluvial gold potential have not apparently been overly successful. Besairie (1966 p 281b) mentions difficulties in bringing water to the various placers but this explanation sounds unconvincing (IMR's opinion).

 Maha River

Several primary prospects are known in the Maha R. valley. Anajaridaina prospect, 2 km to the
west of Morafeno village, is in a mylonitic zone rich in quartz-pegmatitic veins which are rather
discontinuous. Another prospect, Manakana, 15 km west of Anajarindaina, is in numerous veins of chlorite-rich schists: the paragenesis consisted of pyrite, chalcopyrite, rutile and some gold.

The two prospects of Ambia-north and Ambia-south, 7 km to the north-west of Morovato, were
exploited in the 1930s. The mineralisation was hosted in sulphide-rich quartz veins occasionally associated with calcite or magnetite.

The alluvial deposits of the Maha are in terraces and flats. Most of the terraces have been more or less exploited in the past. The flats are now largely covered by coffee plantations. In the terraces a loose conglomerate of variable thickness (0.2 to 2 m) is overlaid by sterile lateritic clays 3 to 7 m thick. The gold-bearing alluvions are very clayey and require a thorough washing ("d‚bourbage"). The ore grades range between 0.3 and 2.5 g/m3.

Saka River

Several primary prospects are known in the valley of the Saka River. The already mentioned
Namolika prospect is one of these and it has been worked underground. Similarly at Tsaramiandana a gold-bearing quartz vein has been exploited by shafts. The largest known alluvions are: Andakatsiefo, Saka-Manama and Ambodiara. These and others are only a few km away from Vohilava village (sketch 7/10). At Fadransana on the Bealana River, 34 kg of gold was produced between 1911 and 1928. Not all these alluvions have been exhausted. Some were still being worked by "artisanal" means at the time of compilation of the present report (1995).

Prospection on the river-beds of Saka and Maha rivers   

As this report is more oriented toward the hard-rock gold potential rather than the alluvial one,
the operations on the Saka and Maha rivers will receive only a rapid coverage mainly from
Besairie (1966, 1969) texts.

A exploration program was carried out on these rivers between 1939 and 1940 with a banka drill. This work has resulted in the observations below, which are essentially applicable to most rivers on Madagascar's east coast as the hydrographic regime is essentially the same.

The rivers of the Saka and Maha type have a bedrock of very irregular surface with numerous
rapids and waterfalls which explains the great irregularity in the thickness of the alluvions.
The alluvions are only coarsely classified and they are reworked at every flood, the gold bring
redispersed within the alluvions. Local concentrations vary from season to season. These
concentrations occur either at the surface of the alluvions or in the black sands [magnetite?]
within the alluvions. These concentrations are generally at the borders of the alluvions, and
slightly downstream of eroded banks or mined terraces.

Six exploration augers-drills on the Maha in 1939 indicated an average grade not above the 0.1 g/t Au. On the Saka River 48 Banka holes have been sunk. The only grades worth mentioning are:

1   g/m3 (two holes)
0.7 g/m3 (one hole)
0.5 g/m3 (two holes)
0.3 g/m3 (six holes)

These holes clearly showed that if the present alluvions appear rather rich at the surface, they
are disappointingly poor at depth. The alluvions' thickness ranges between 2 and 6 metres. Gold mining by diving was limited to the upper part of the alluvions.

This exploration campaign indicated that the alluvions could not be exploited by conventional
dredges. In view of this the Madagascar Mines Service built special equipment (patent NeviŠres) which could suck the alluvial sands at a given depth without being obliged to absorb its sterile parts.

The dredge also was equipped with a water jet to facilitate the disgregation of the alluvions and an suction duct. The production of this contraption was 6 m3/h in medium-sized gravels and up to 15 m3/h in sands and grits. During experimental tests at 4 m depth the dredge recovered, after a water injection of one minute and an aspiration of one minute, 65 % of the lead and 55 % of the gold that was sunk in the alluvions. It was estimated that this type of small dredge was likely to give very satisfactory results in stable alluvial deposits even in coarse gravels.

The dredge was then tested directly on the Saka with the aim of exploiting some the sectors
indicated most favourable by the Banka drills. The results were extremely poor. They showed that [predictably] there was no continuity between two holes with high gold grades. It was therefore impossible to estimate an average grade from the drill-hole results and the average grades obtained by this primitive suctio n dredge were always inferior to the grades indicated by Banka drills.

In reality the description of the gold alluvions of the Maha and Saka rivers are no different to
the ones in tropical rain forests (the eastern part of Madagascar) with a hydrography draining
from gold-bearing laterites.

Some parts of Papua New Guinea, British Guyana and of Zaire's Kivu province present the same conditions. The problems of efficient gold recovery from comparatively small and erratic placers are not new. Literally thousands of small floating dredges, some of them very ingenious, have been built in Australia, South-East Asia and South America for the exploitation of these placers,
invariably with mixed results.

In the 1980s the French BRGM (through its subsidiary Soditra - Sodiloc), built a state-of-the-art
small dredge which, although built and tested in Madagascar, had the world market in mind. These dredges, called "Dragor 6"" and "Dragor 4" (sketch 7/1/1), are not significantly different from US models developed two decades before. 

The general geology and morphology of Madagascar does not seem favourable to the formation of large alluvial gold deposits like those of Brazil, Venezuela or some parts of Papua New Guinea. Exploration for these types of deposits will probably be outside the aims of large foreign investors to whom this report is aimed.

BEFORONA GOLD DOSTRICT

Location and History

The Beforona gold district is bisected by the main road and railroad linking Antananarivo to
Toamasina (formerly Tamatave), the main Madagascan port on the east coast. This gold district can easily be reached by 124 km of good, surfaced road from Antananarivo (sketch 7/15).

Beforona village, central to the gold district, has no facilities, but 30 km to the east the
small town of Moromanga (comfortable hotel, telecommunications) is a convenient base. Most of the deposits of the Beforona gold district can be reached only by 4WD vehicles or on foot.

Most of the deposits of this goldfield were already productive in 1900 when this district was, in
terms of production, the second largest in Madagascar.
  
Geology

The gold deposits of the Beforona district are hosted in migmatites and amphibolites of the
Beforona group (C5) of the Vohibory system which have been dated at 2,700 MA (Besairie, 1964). The gold mineralisation has probably been introduced or significantly remobilised in the major tectonic event of 2,104 MA, but later remobilisations cannot be excluded.

Regionally, the gold-bearing migmatites and gneiss of the Beforona gold district seem to be the extension of similar formations of the Mananjari system of the Vohilava-Ampasary gold district, 500 km to the south. The main difference seems to be that while the Vohilava-Ampasary gold is hosted in a Fe-Ca-Mg metamorphic series, the Beforona gold is hosted in a more sialic environment: possibly the metamorphic grade is also higher (migmatites rather than schists) than the Vohilava-Ampasary series.

Also similar to the Vohilava-Amposary is prevalent north-south regional tectonics. The Beforona district's known mineralisation consists of free-milling gold and gold in Cu-Fe sulphides disseminated in quartz veins. 

Table 6 lists only three recorded deposits, all primary, for the comparatively small and
understudied Beforona gold district.  Significantly, 27 of them are primary.

 Individual deposits


 Marovato

The important Marovato deposit is only 15 km from Rogez Station on the Tananarive-Toamasina railroad. It is one of the last primary gold deposits to have been industrially worked in Madagascar: the deposit was abandoned in 1952. It was during Wold War II that Marovato attracted new interest and investment from the Madagascar Service of Mines Exploitations (Mr A Lenoble). The Marovato deposit consists of three gold-bearing quartz veins conformable within the migmatites:

VEIN I: striking over 4 km and prospected by trenches, shafts and galleries at several levels
over a length of 405 m and a depth of 35 m. Its thickness ranges from 35 to 150 cm.

VEIN II: striking about 1,800 m: only small workings have taken place in this vein.

VEIN III: rather far apart and less rich than the previous two veins. 

The ore is in quartz with auriferous pyrites and chalcopyrites and a few zones of free-milling
gold. In 1945, at Marovato, there was 520 m of underground development and 70 m of shafts. Power was supplied by a hydraulic plant of 30 CV. Mr Lenoble estimated known reserves of 5.5 tonnes of gold (177,400 oz) at unreported cut-off grades.

Preliminary tests over 250 tons of ore yielded 3,025 kg of gold or 12 g/t Au. At the time it was
estimated an industrial recovery of 10 g/t plus about 7 g/t Au in the sulphides. A further, well
quartered, sample treated by fire assay gave an average ore grade of 13-17 g/t Au. The plant was destroyed by fire in 1947 although some minor prospecting activities took place until 1952 when the mine was definitely abandoned.

Grigri

The Grigri prospect, 45 km east of Moramanga, raised high hopes in 1905 but ended up as total failure after some underground workings. The main deposit is in a large quartz vein 80 m long, 10 m thick at most, and at least 13 m deep. Underground surveys (tracages) were carried out at several levels. This mass of white quartz showed an average grade of about 6-7 g/t Au with occasional pyrite-rich zones with higher grades. Gold occurs either as an inclusion in pyrite or, more rarely, as free-milling.

Other smaller, but not richer, gold-bearing quartz veins occur nearby the main Grigri prospect.

   
ANDRARONA GOLD DISTRICT



 Location and History

The Andrarona gold district occurs in the extreme north-east of the island in the Masoala
peninsula, north of the Antongil Bay. This is a rather minor gold field, often quoted in the
literature as Antalaha, from the omonymous seaside town.

The Andrarona gold district can be reached either by a twice-weekly plane to Iharana (Vohemar) or Sambava townships and then by by road, mostly unsurfaced to the village of Antalaha (with only primitive accommodation). Conversely, it is possible to reach Antisarabato-Antalaha by charter plane. The best base for the Andrarona gold district is the town of Sambava (hotel, telecommunications and other services) 90 km to the north of the goldfield (see sketch 7/13).

This small gold district has officially produced only 270 kg Au between 1905 and 1920 - the
period of major production for Madagascar.

 Geology

The geology of the Andrarona gold district is unique in Madagascar. Andrarona is the only
district where gold is clearly related to granitic intrusions. Although the gold mineralisation
occurs in Precambrian schists and micaschists of the Beforona group of the Graphite System, the mineralising episode appears related to the emplacement of the Antonigil granites tentatively dated at 770 MA (Besairie, 1964), but possibly older.

However, there are reservations about these Antonigil granites being the primary source of gold, as in some works consulted these granites appear much older, and possibly cratonic (Hottin, 1972). On the other hand the BRGM (1985) points to a possible - and highly unlikely - Devonian age for the Andrarona schists. The lack of modern geochronology of the region makes these discussions rather futile. We also note that the consistent presence in the same goldfield of two different gold finenesses (975 and 850) could indicate a multiple origin of the gold.

There is no obvious tectonic control in the Andrarona gold deposits but the region is strongly
tectonised, being in one of the regions of maximum stress linked with the break-up between India and Madagascar.

The recent activities of artisanal miners in the previously unknown region of Marantsetra (see
sketches 5/1, 7/1 and 7/13), about 120 km to the south west, may indicate that the Androrona gold district could be much larger than previously thought.

Table 6 lists 11 recorded deposits, all primary, for the Andrarona  gold district, five of them
belonging to the comparatively rare a4 genetic type (see chapter 6.5).

Individual deposits

Antsahivo

This primary deposit, and relative alluvions, occurs 18 km south of Antalaha and, to date, has
been the largest known occurrence in the district. The deposit apparently lies at the contact
zone between a granitic massif (Masoala granite) and the schists and quartzites of the Beforona group. The schists are cut by a swarm of quartz veinlets both conformable or uncomformable. The quartz is milky or blue-coloured, often with tourmaline or rutile needles. Gold occurs in pyrite, although alteration has occasionally liberated free-milling gold. Grades are reported at between 6 and 7 g/t with occasional peaks of 30 g/t. 

Fatanambo

Besairie (1966, p 270b) mentions this primary deposit occurring to the west of the Antsahivo
River, where a quartz vein was followed over 200 m by superficial working. Recorded grades were around 30 g/t Au. This large vein, almost concordant with the schists, was dipping 75§ and is cut by several veinlets forming a stockwork pattern with an average grade of 6-7 g/t Au over an average thickness of about 1 m. Measured reserves have been calculated at 86 kg of gold with possible reserves of 172 kg. We ignore the  methods of these calculations (IMR's note).

 Andrarona 

At Andrarona, in the upper valley of Marambo, gold-bearing quartz (milky, blue or haline) veins
with rutile and tourmaline inclusions have been mentioned but without further details (Besairie,
1966 p 270a).

 Alluvial deposits

In the Andrarona goldfield several, presumably small, alluvial deposits have been recorded. Among these: Andongozabe, Ambodihintsy, Ambalambato, Andranomena and Antsahabe.


VAVATENINA GOLD DISTRICT



  
 Location and history

The Vavatenina gold district is located 80 km north of the provincial capital, and major port, of
Toamasina (formerly Tamatave). It can be reached by daily flights (Air Madagascar - Boeing 737) to Toamasina and by 157 km of surfaced road to Vavatenina: but this village though central to the goldfield offers no facilities. The best base to this goldfield is the pleasant seaside town of Fenoarivo (hotel, telecommunications, landing strip) 40 km of surfaced road to the east of the goldfield.

Vavatenina gold district is the smallest in Madagascar with a known extension of only a few tens of km2. In the past (Besairie, 1966) the Vavantenina goldfield was considered jointly with the much larger Berofona one and statistics are therefore rather confused.

In spite of its reduced area the Vavatenina district has been a significant gold producer in the
past: 40 kg of gold was produced in only six months in 1902. But production decreased sharply from 1904 onward. Production took off again from 1941, with 8.8 kg produced in 1942 and 11 kg in 1944. Present production is entirely due to artisanal miners. 

 Geology

The geology of Vavatenina is charaterised by the predominance of of biotite-micaschists,
occasionally with kyanite. These schists are frequently cut by pegmatitic swarms and
quartz-feldspar veinlets which correspond to the migmatitic front in the Ambodiriana group (C7) of in the Vohibory system. These micaschists have been dated at 2750 MA and the regional tectonics show strong faulting striking 10§ to 15§ to the east (Besairie, 1964, Feuille du Centre). There are no obvious granitic intrusions nearby.

The average gold finesse is 950, possibly pointing to a sulphide-poor environment (IMR's note).
Practically all rivers and streams in the region are auriferous, although they all are rather
small: never more than creeks, which limit their potential. A possible correlation of this
district with the Beforona gold district to the south in very similar geological and tectonic
conditions is tempting, as both are hosted in the Vohibory system (see Plate 1).       

The only two (but primary) deposits listed in Table 6 point to the relative lack of knowledge of
the apparently small Vavatenina gold district.


Individual deposits

The three individual gold deposits recorded are about 10-13 km west of the Vavatenina village
(Besairie 1969, feuille Tamatave). There no available descriptions of these deposits. A thermal spring 8 km to the north of these prospects is well worth a geochemical characterisation (IMR's opinion). 
  •  Numerous artisanal workings with an estimated production of 3 to 4 t of gold annually.The Dabolava region has been one of the most productive..
Abstract from Geology and petrology of the Dabolava Region, West-Central Madagascar, with emphasis on granite-hosted gold mineralization: Rakotoarimanana, Rindrahasy Harilala

The Dabolava region is an area of approximately 600 km2 and is situated on the western edge of the Precambrian in west-central Madagascar. The geology mainly consists of Proterozoic amphibolite facies metavolcanic rocks, inter-layered with minor metasedimentary rocks, crosscut by granodioritic to gabbroic plutons. The country rocks of the granodiorite and gabbroic plutons are composed of 50% amphibolites, 30% quartzofeldspathic gneisses and 20% metasedimentary rocks, mainly carbonates. The amphibolites consist dominantly of 

hornblende with plagioclase and minor quartz groundmass, although orthopyroxene, clinopyroxene, chlorite, and biotite are present in certain samples. They have tholeiitic affinities and may have been derived from basaltic lavas. They contain felsic segregations of tonalitic composition that possibly represent migmatitic leucosomes, with hornblende concentrated in associated melanosomes. The amphibolites are highly deformed compared to  the plutonic rocks. Meta-quartzofeldspathic rocks of dominant rhyolitic compositions are  interlayered within the amphibolites; these may represent felsic volcanics coeval with the metabasalt. Metamorphosed carbonates are also interlayered within the amphibolites. This assemblage of supracrustal rocks is intruded by Neoproterozoic granitoid and gabbroic  plutons, and granodiorite dykes. The composition of the majority of the plutons in the area of study is mainly granodioritic, with minor quartz diorite and quartz monzodiorite. They are metaluminous and contain quartz, plagioclase, with minor K-feldspar (microcline); biotite and hornblende constitute the ferromagnesian minerals. The granodiorites have a prominent  foliation defined by biotite and hornblende. According to their chemical and mineralogical  composition, the granodiorites are classified as I-type in origin. Gold mineralization is associated with the Neoproterozoic granodiorite plutons, mainly the Dabolava and the Ambatomiefy plutons. It is hosted within quartz veins that are generally  oriented parallel to the foliation of the host rock. A limited degree of alteration is observed  within the granodiorite, with the alteration assemblages consisting of biotite, pseudomorphic chlorite, calcite, and sericite. Gold is associated with hydrothermal biotite and sulphide assemblages consist of pyrrhotite, arsenopyrite with minor pyrite and chalcopyrite, magnetite and ilmenite. The chemistry of analysed gold grains from the Dabolava pluton shows that they mainly consist of 95-97% gold with the remainder composed of Ag, Hg and Cu. A gold concentration of up to 2232 ppm was observed in one of the gold excavations within the Ambatomiefy pluton. Microthermometric studies reveal three fluid types, including a high salinity fluid (type 4), a CO2-rich fluid (type 1-a), and an aqueous type (type 3). It is  suggested that the CO2-rich and high salinity fluids were exsolved from the magma. With decreasing temperature a low salinity CO2-H2O-NaCl fluid (type 1-b, type 2) (Th ranges from ~ 220-350° C) resulted from heterogeneous mixting of a CO2-rich fluid and a low salinity  aqueous fluid. Therefore, fluid inclusion studies indicate a magmatic origin of the mineralizing fluid(s). A porphyry-type deposit is suggested for the gold mineralization in the study area, as it is associated with I-type granitoid plutons, the mineralizing fluid (s) are of magmatic origin, and gold is associated with chalcopyrite, albeit in minor amounts. Based on the rock associations observed in the field, which consist of metabasalts interlayered with minor coeval metarhyolite, with associated intrusive plutonic rocks, as well as trace  element discrimination diagrams, an active continental margin tectonic setting is inferred for  the rocks in the study area. Two samples from the granodiorite plutons and one sample from a gabbro body were dated using U-Pb single zircon geochronology. A sample from the Ambatomiefy pluton yielded an age of ~1002±3 Ma, which is interpreted to represent the crystallization age of the pluton. The Dabolava pluton has also been dated, and a similar age of 1008 Ma has been obtained. A gabbro sample from a smaller mafic body in the area has been dated at 982±2 Ma. This defines a ~26 m.y. period of Neoproterozoic magmatic activity. 

 An age of 982.3±2 .9 was also reported from a gabbro body located in the southern part o Madagascar (Amborompotsy-Ikalamavony). These provide evidence of the presence of 1000   Ma magmatic activity in Madagascar. The extent and the significance of this magmatic event  are not yet understood although it could be related to the Mesoproterozoic event associated  with the assembly of the supercontinent Rodinia. The identification of granitoids of similar age and character in Madagascar and within Gondwana has economic significance regarding the potential of these granitoids for porphyry-type gold mineralization. Therefore, this is  useful for future gold exploration.


The government of Madagascar invited a shortlist of companies to submit proposals for the development of three known gold deposits: Betsiaka in the region of Ambilobe, and two deposits in Maevatanana in the region of Mahajanga. Deadline for submission of offers was set for end 2007; the three blocks were to be awarded in the course of 2008.
  • Pan African Mining Corporation (Canadian, were also active in Zambia, Mozambique, Congo and North Africa) held prospecting permits in 16 areas throughout Madagascar, half of which cover gold prospects. The company comprehensively compiled historical data and was engaged in early stage exploration. In 2006 Pan-African held approximately 4,087 km2 of permits covering three major gold targets (Dabolava, Andavakoera and Andramasina). In 2005, Pan-African reported to have discovered high-grade gold deposits at its western Dabolava concession, a licenced area situated 180 km west-southwest of Anatananarivo. .Pan-African Mining said in June 2005 that it had found high grade gold deposits after the first phase of drilling at its western Dabolava concession. Yields were 32 grams per ton of rock in some places, the company said. (Asia Thai Mining Co. Ltd. ("ATM") and 0819615 B.C. Ltd., a wholly owned subsidiary of ATM, bougt all the shares of Pan African Mining in April 2008.)
  • Majescor Resources (Canadian) gold and base metal properties in Madagascar include, in addition to the Besakoa polymetallic VMS Cu-Au-Zn-Ag prospect in Tulear Province, southern Madagascar.: the Daraina property in North Madagascar, where initial surface sampling in August 2006 returned grades of up to 87 g/t gold and 75 g/t silver; the Analalava property, which is host to a series of untested historical Ni-Cu showings, and is completely surrounded by BHP-Billiton claims; and the Ankaramy property which shows potential for both SEDEX-type (Pb-Zn) and epithermal gold-silver. In April 2008, Majescor announced it had entered into a letter of intent with Sunridge Gold Corp. (“Sunridge”), an experienced Africa-focussed gold and base metal explorer, whereby Sunridge can acquire up to a 100% interest in four gold and base properties held by Majescor in Madagascar. Majescor acquired the land package under option to Sunridge from a local Malagasy mining company in 2006. The principal asset of the property package is the Besakoa license located in the Atsimo-Andrefana region of South Central Madagascar. The Besakoa property holds a series of historical sulphide occurrences including the “Main” Besakao polymetallic prospect, Madagascar’s principal volcanogenic massive sulphide (“VMS”) occurrence. The property consists of a block of 144 CDCs covering 56 km2.In January of 2007, Majescor completed a first core drilling program on the main Besakoa prospect. The purpose of the drilling was to confirm and upgrade geological data derived from historical core drilling dating back to the 1950s. Eight holes were drilled and core was recovered to a maximum depth of 78 metres. Iron oxide and/or copper-zinc-bearing sulphides were observed in all eight drill holes drilled, with intersections grading of up to 21.5 m of 0.7% copper, 0.5 g/t gold, 1.1% zinc and 21.4 g/t silver. The Besakoa property area is considered to be an extension of the same basement rocks of the East African Arabian-Nubian shield which hosts Sunridge’s Asmara and Nevsun’s Bisha VMS deposits in Eritrea. Majescor and Sunridge believe that the Besakoa property area may represent a new emerging Neoproterozoic VMS district as there are numerous gossan outcrops on property and surrounding area which appear to be oxidized remnants of underlying VMS style mineralization. The Besakoa property area last underwent systematic exploration during the 1950’s. Since Majescor acquire the property in 2006, the area has seen resurgence in exploration activity. In August of 2007, Uranium Star Corp. (“Uranium Star”) announced it had acquired a 75% interest in the Three Horses property located immediately to the South of the Besakoa property. Exploration work on the Three Horses property began in the fall. Uranium Star reported finding several gossanous boulder occurrences, believed to overlie massive sulphide mineralization, on the property. A helicopter-borne EM-magnetometer survey was also completed. Uranium Star intends to drill the Three Horses Property in 2008. Majescor and Sunridge are committed to moving the Besakoa property forward in 2008. To this effect, the partners have planned a focused ground exploration program for the summer 2008 field season. This program will include reconnaissance and systematic prospecting and mapping, ground geophysical surveying and soil geochemical sampling.

Graphite
  • The main producers are Societe Miniere de la Grande Ileand Establissments Gallois from widespread occuurences along the eatern coast near Tamatave. ( Graphite Technology was incorporated in Pennsylvania on April 27, 2004, following which time Graphite Technology acquired the graphite processing equipment of Applied Carbon Technology (America), a corporation involved in certain processing and sales of graphite. On January 31, 2005, Graphite Technology reincorporated in the State of Delaware. On July 27, 2005, Graphite Technology entered into a purchase and sale agreement with Societe Miniere de la Grande Ile, ("SMGI"), M. Bertil Akesson, owner/operator of theAmbatomitamba Graphite Mine and four contiguous graphite mines located in Madagascar by which Graphite agreed to purchase a 50% common equity interest inSociete Malagasy du Grafit s.a.r.l., a Madagascar limited liability company ("SOMAGRA"), as and at the time that SOMAGRA owns and has rights to operate and develop the Ambatomitamba Graphite Mine and Sahanovo Mine and contiguous surface mines at AmbodihasinaSandraka,Ambiani and Sahamaloto. On March 26, 2006, Graphite Technology acquired that 50% common equity interest in SOMAGRA. The purchase and sale agreement also provides Graphite Technology the option to purchase the remaining 50% of SOMAGRA less one share at any time within three years of the closing. Prior to closing, all graphite mine claims and mine leases controlled by SMGI, affiliate companies of SMGI, or by Akesson,) The deposits are in a region where lateritic deposits of iron and bauxite also are found. The graphite occurs in highly metamorphosed schists and gneisses that have been weathered deeply to soft, ferruginous clays. The graphitic content of the original rock has been raised through the natural leaching process. The graphite, being resistant to weathering, is found among the weathered residue. The crude ore contains 3%-10% graphite, of which about two-thirds is large flake and one third is fine flake. The nongraphitic portion of the flake product is uniform and consists (after oxidizing) chiefly of a clayey residue with some quartz and a sprinkle of accessory minerals such as mica, zircon, rutile, and epidote. Sulphur compounds are absent and iron is low.
  • Energizer Resources Inc TSX:EGZ and Malagasy Minerals Ltd announced on May 1, 2012, results from the Molo Deposit of its Green Giant Project in southern Madagascar. Assays show6.94% carbon over 20 metres, 7.4% over 87 metres, 14.63% over 13.5 metres, 7.27% over 54 metres, 7.92% over 88 metres. Energizer holds a 75% interest a nd acts as project operator on the Joint Venture Property, which surrounds Energizer’s wholly owned Green Giant Graphite-Vanadium Property on three sides. Energizer has identified 17 graphite trends with a cumulative strike length of more than 320 kilometres on the Green Giant and JV properties. Within two weeks the company plans to begin a Molo resource delineation program, which will take an estimated two months to complete. Shortly after drilling begins, DRA Mineral Projects will begin quantifying data for a preliminary economic assessment of the Molo deposit.The Green Giant Property has a vanadium resource of 49.5 million tonnes grading 0.693% vanadium pentoxide (V2O5) indicated and 9.7 million tonnes grading 0.632% V2O5 inferredEnergizer Resources Inc. (TSX: EGZ) (OTCBB: ENZR) (FWB: YE5) announced on 29 August 2012 that it had received additional assays from its recently completed National Instrument (NI) 43-101 graphite resource drill program on the Molo deposit. The Molo deposit is located in the Green Giant Graphite project, and is part of the joint venture (JV) property with Malagasy Minerals Limited in Madagascar. Energizer has a 75% ownership interest and is the operator of the Project. The recently completed drill program will provide the necessary data to complete a National Instrument (NI) 43-101 graphite resource, which will be part of the Preliminary Economic Assessment (PEA) due in Q4 of this year. DRA Mineral Projects, Africa's largest mine engineering, construction and operations firm, is authoring the PEA Study, while Caracle Creek International Consulting Inc. of South Africa is authoring the resource statement. In total, 41 diamond drill holes over 8,450 metres, and 18 trenches over 2,100 metres were completed during the program. The Company has now received assays for the first 9 (of 41) drill holes, and the first 8 (of 18) trenches completed during the course of the recently concluded resource delineation program. Coupled with the 6 diamond drill holes and 1 trench completed during the December 2011 exploration program, this assay data confirms that the Molo has a very large footprint. The Molo deposit exists within a folded sequence over a 2 km strike length. In the north, it is between 50 to 60 metre wide then flares to over 500 metres in width.  From this point, the graphite deposit tapers down to a width of approximately 250 to 350 metres.  Finally, the deposit splits into two ‘arms' of between 50 and 100 metre widths respectively. Drill and trench data received to date, as well as mapping, prospecting and geophysical surveying, confirms graphite mineralization at surface, and over an area of at least 250,000 m­2.  Depth of mineralization has been confirmed by drilling in excess of 300 metres. Based on the size of the Molo footprint, as well as the tenor of mineralization found in the 15 drillholes (9 from 2012 and 6 from 2011) and 8 trenches received to date, the Company is confident of delineating a deposit in excess of 100 million tonnes at an average grade greater than 6% carbon (graphite). An assay table summarizing all results is also provided on the Company's website.
  • Cline Minining Corporation owns the Bekisopa iron-ore-deposit properties (Bekisopa East) in Madagascar. The BRGM, Madagascar government and the U.N. early data base reports original Beki-East iron deposit at between 25 per cent and 65 per cent averaging 45 per cent, resource 150 million tones, largely magnetite surface ore. Additional airborne survey in 2007 found additional step-out separate mineralized areas (Bekisopa West) which Cline followed up by ground geophysics localizing the important areas for drilling in 2008. The ground geophysics program in late 2007 was also extended to the existing Bekisopa East deposit revealing the presence of an extensive mass which is to be drilled following the wet season in Spring 2008.
  • The Chinese group Wisco has been awarded the iron ore deposit Soalala. The iron reserve of the site is estimated at 562 Mt and is capable of producing about 3.5 Mt per year.  The deposit is not far from the coast, south of Mahajanga, but road improvements are necessary to make it more accessible. A port site is planned and a power plant;  the planned investment by Wisco is expected to exceed 2 billion USD.

Nickel

  • Dynatec Corporation (Canadian, DY.TO) announced on October 30, 2006, the signing of a shareholders agreement for the Ambatovy Nickel Project. Under the agreement, Dynatec has been appointed project operator and will retain a 40% ownership interest. A 27,5% interest in the Project will be held by each of Sumitomo Corporation and Korea Resources Corporation (leading a consortium of Korean enterprises including Daewoo International Corporation, Keangnam Enterprises Ltd. and STX Corporation). SNC-Lavalin Inc. has agreed to acquire a 5% interest in Ambatovy coincident with the closing of the project debt financing. Dynatec will receive US$852 million of financial support from its partners, positioning it to fund its equity requirements for the Project and to meet a significant portion of its guarantee obligations for project debt financing. Ambatovy is among the largest nickel projects under development in the world, with annual design capacity of 60,000 tonnes of nickel and 5,600 tonnes of cobalt. It is anticipated that Ambatovy will be placed near the bottom of the industry cost curve based on expected low nickel production costs. The Ambatovy Project is based on mining two ore bodies that are about three kilometres apart. The Ambatovy and Analamay deposits are both laterite nickel deposits formed by the leaching of the ultramafic portion of a large intrusive complex. The deposits cover an area of about 1300 hectares, with a thickness from 20 to 100 metres (average thickness is approximately 40 metres). More than ninety percent of the deposit is classified as ferralite, some of which is underlain by saprolite. A material type termed low magnesium saprolite (LMS) lies below the ferralite and between the ferralite and saprolite, where the latter is present. Only the ferralite and LMS have been considered in the mine plan. The distribution of the saprolite is erratic; consequently it has been classified as inferred, and is not included in the measured and indicated resource, although its exploitation may prove to be economic. Exploration on the property has occurred in four campaigns: Bureau des Recherches Géologiques et Minières (BRGM) in 1962; GENiM, a mining consortium comprising Anglo-American, Société le Nickel, Ugine Kuhlmann, and BRGM in the early 1970s; Phelps Dodge in the mid-1990s; and Dynatec in 2003 and 2004. A total of 1282 diamond drill holes have been drilled representing approximately 55 000 metres of drilling. In addition, sample pits have been dug and appropriate surface mapping completed. Proven and probable mineral reserves are estimated at 125,0 million tonnes at an average grade of 1,04% nickel and 0,099% cobalt; additional low grade ore is estimated at 39,4 million tonnes at a grade of 0,69% nickel and 0,064% cobalt; this low grade ore is scheduled to be stockpiled then reclaimed and processed at the end of the mine life; average ore grade over the first 10 years of the mine plan is estimated at 1,12% nickel and 0,101% cobalt; the mine life is estimated to be 20,5 years, plus 6,5 years of stockpile recovery, giving a total production plan of 27 years; total recoverable metal over the production plan is estimated at 1,34 million tonnes of nickel and 122 000 tonnes of cobalt. Sherritt International Corporation and Dynatec Corporation jointly announced a transaction on April 20, 2007, whereby under a Plan of Arrangement Sherritt will acquire all of the issued and outstanding common shares of Dynatec for a total value of C$1.6 billion. Sherritt International Corp. of Toronto said in January, 2014 it had reached commercial production at the Ambatovy nickel operations. Located, 80 km east of Antananarivo, the project is a joint venture of Sherritt (40% and operator), Korea Resources (27.5%), Sumitomo Corp. (27.5%) and SNC-Lavalin (5%).
    Ambatovy produced its first finished nickel and cobalt in Q3 2012. It produced 5,695 tonnes of finished nickel and 493 tonnes of finished cobalt.
    The project includes an open pit and an ore preparation plant at the mine site. Concentrated laterite ore is delivered by pipeline the process plant and refinery on the east coast. The project has an annual design capacity of 60,000 tonnes of nickel and 5,600 tonnes of cobalt with a mine life of 29 years. It is expected to be the world's largest nickel and cobalt producer from laterite ores.
    Further information is available at Ambatovy.com.
  • Diamond Fields International Ltd announced on 9 May, 2007, that it had exercised its option to acquire the rights to the Valozoro nickel property in Madagascar and owned 100% of these exploration rights which are valid until May 2011. The Valozoro nickel deposit is located 60 kilometres north of the town of Fianarantsoa in south central Madagascar and is reported in the Catalogue des Principaux Gites Mineraux de Madagascar (Catalogue of Principal Mineral Deposits of Madagascar). During 1956 and 1957, UGINE completed an extensive prospecting program and reported an estimated resource of 3.7 million tons of lateritic ore (derived from an altered peridotite host) grading 1,75% nickel containing 65,000 tonnes of contained nickel metal.
  • Jubilee Platinum plc reported encouraging results in October, 2007, from the most recent borehole drilled on the Antsahabe prospect, in the northern area of its Londokomanana property, in Madagascar.
    The borehole intersected 32 m of continuous nickel copper and sulphide mineralization at a shallow 30 m depth from the surface.
    The Londokomanana project is a joint venture with TransAsia Minerals Limited, which has the right to earn in 51% of the project, by spending $7-million.

Oil and Natural Gas


The discovery of the two giant exhumed oil fields of Bemolanga and Tsimiroro at the beginning of the twentieth century has aroused the petroleum exploration activities in Madagascar. The petroleum exploration history is divided into three main periods:
Prior 1960 , it was conducted mainly by SPM, a subsidiary of ELF Aquitaine (the French national oil society),
From 1960 to 1975: first entrance of other international companies than French in oil exploration (Chevron - Agip – Conoco - Teneco),
Since 1976, year of OMNIS creation : partnership with important and major international oil companies (Mobil - Oxy - Amoco - Agip - Shell - Maxus - BHP- Hunt Oil - Triton - Gulfstream - Vanco - Norks Hydro - Sterling Energy – Vuna Energy - ExxonMobil).

Geophysical surveys:
71,000 km of 2D seismic
3,600 km² of 3D seismic
195,000 km of aeromag 
11,000 km of micromag 
33,000 km of magnetism 
87,000 km of gravity

Exploration wells: 75 wells
1 in onshore Ambilobe Basin
8 in Majunga Basin 
65 in Morondava Basin 
1 in offshore East Coast


In April 2006, Madagascar opened up 96 new offshore oil and natural gas blocks for tender. The government accepted bids from interested parties until November 17, 2006. The licensing round is overseen by the Office des Mines Nationales et des Industries Strategiques (OMNIS) and TGS-Nopec, which completed seismic data on the blocks. International oil and natural gas companies active in Madagascar include ExxonMobil, Norsk Hydro (Norway), Vanco Energy (U.S.), Vuna Resources (China) and SUNPEC International Ltd (China). The government was in the process of negotiating concessions with several other oil giants, including Chevron, Texaco, Royal Dutch Shell, BP, Total, Norway's Statoil and China's National Petroleum Corporation.
  • Oil production: 90.59 bbl/day (2004 est.)
  • Madagascar Oil is the current license holder of the Tsimiroro and Bemolanga tar sand deposits in the onshore Morondava Basin of Madagascar discovered in the early 1900s. Tsimiroro is a large heavy oil field at 100-300m depth. The block, with an area of 6,670 km2, is located in NW Madagascar about 100km from the coast. Sixty-one wells have been drilled on Tsimiroro’s 70 km² core area to date. With the use of SAGD the expected recovery factor is estimated to be 55%. The Company is currently executing a pilot project on Tsimiroro. Tsimiroro is also prospective for conventional hydrocarbons. A Tsimiroro sample of 22º API oil was reported in 1988 from a test well in the south of the block.l
    Bemolanga is a bitumen field at 0-30m depth with a reserve of 16.6 billion barrels (9.8 billion recoverable). The Bemolanga block, with an area of 7,175 km2, is located in NW Madagascar about 120km from the coast. Thirteen wells and over 500 core-holes have been drilled from the 1950s to the early 1980s and the surface mining area is defined by less than 40 meters depth to top tarsand. The average overburden in the surface mining area is around 15m, considerably less than average overburden in Canada. Madagascar Oil also has a 100% interest in conventional oil and gas exploration onshore blocks 2103, 3105, 3106, 3107 and a 50% interest in block 3109, where Tullow Oil is the operator.
    Construction phase of the Tsimiroro Steam Flood Pilot is reaching completion and steam injection into the first wells has commenced. During 2012 the Company drilled 28 wells in the Tsimiroro field: 16 production wells, nine steam injection wells and three observation wells. In addition several water wells and water disposal wells were drilled The Steam Flood Pilot is designed to evaluate the potential production rates and recovery factor that could be achieved through thermal stimulation A 24,000 line km Airborne Gravity Gradiometry survey was conducted across MOIL’s three exploration blocks and an initiative is underway to consolidate all available data to assess the potential for light hydrocarbons

    Tsimiroro Oil Field
    Source: Madagascar Oil
  • In 2005, U.K.-based Sterling Energy sold 70 percent of offshore Ambilobe and Ampasindava licenses to ExxonMobil. ExxonMobil plans to finance exploration work on the licenses.
  • In August, 2005, Aminex plc announced the award of onshore exploration acreage in Madagascar. Aminex, with partner Mocoh Resources Ltd.(“Mocoh”), has been awarded the rights to Block 3108, known as Manja, onshore the west coast of Madagascar and covering an area of 10,725 square kilometres, (approximately 2.6 million acres).
    The rights to this block are held through a Production Sharing Agreement (“PSA”) between OMNIS, the Madagascar state oil and mining organisation and Amicoh Resources Limited (“Amicoh”), a newly formed company, in which Aminex and Mocoh each holds an equal number of shares and through which the shareholders will fund exploration activity in equal proportions. Mocoh is an active downstream African petroleum group with existing assets and distribution operations in a number of countries including Madagascar.
  • Tullow Oil plc signed its first licence in Madagascar in early December 2005. Onshore Block 3109 (Mandabe), situated in the Morandava Basin, covers 11,050 sq km in the southwest of the country. The work programme includes a 6,700 km reconnaissance aerogravity survey to aid the design of a seismic acquisition programme. Tullow signed the PSA for a second licence in Oct 2006. The onshore Block 3111 (Berenty) lies adjacent to, and south of, Block 3109 and covers 9,050 sq km. The agreed work programme for the initial 3-year exploration period includes the acquisition of 200km of 2D seismic and the drilling of a well. This licence requires a presidential decree before it becomes effective.

Source: Tullow Oil

Platinum

Jubilee Platinum plc has joint ventures with both Implats and TransAsia Minerals on nickel-platinum exploration projects in Madagascar. In a friendly takeover bid announced on 28 October 2007, Xstrata offered to purchase all of the shares of Jubilee for $23 per share. The offer is due to close on February 15, 2008.
  • Ambodilafa Project (49%- Implats 51%). Jubilee’s 4 kilometres wide by 20 kilometres long Ambodilafa concession is part of an area underlain by mafic-ultramafic rocks. The property is located some 160 kilometres southeast of the Madagascan capital, Antananarivo. Previous regional reconnaissance drilling by others in the area, in 1969, included an intersection of 93 metres of disseminated sulphides, containing pyrrhotite, pentlandite and chalcopyrite. The intersection included a 1,5 metre intercept assaying 2,2% nickel and 0,35% copper. The drill cores were not analysed for their PGE content, but later stream sediment sampling in 1990 defined several drainage catchments in the vicinity of the area drilled, which showed anomalous platinum and palladium values.
  • Londokomanana Project. Located 150 kilometres north of Antananarivo with an inferred 22-kilometre total strike length of nickel-copper mineralization over north (Antsahabe) and south (Lavatrafo) Londokomanana. Peak trench values have been obtained in Lavatrafo of up to 4,62 g/t 2PGE (platinum and palladium) plus gold, 1,2% nickel and 0,39% copper. The Company has drilled two boreholes, LAV1 and LAV2 in the Lavatrafo property (south Londokomanana) on targets identified by geophysics and geochemistry. The two boreholes, some 150 metres apart on strike, intersected a very thick -58 metre and 75 metre true widths - multi-metal nickel-copper-platinum-palladium-gold formation at relatively shallow - 27 and 73 metres depth.
  • Lanjanina Concession located in the south-central part of Madagascar approximately 180 kilometres ( 258 road km.) south of Antananarivo and covers an area of 156 km2 (15,600 hectares). Previous exploration identified copper, nickel and platinum group elements in geochemical soil samples and one drill hole located copper and nickel mineralization within pyroxenites and to a lesser extent gabbros and amphibolites.

Titanium

  • QIT Madagascar Minerals (QMM), which is 80% owned by Rio Tinto and 20% owned by the Government of Madagascar, has built a mineral sands mining operation near Fort-Dauphin at the south-east tip of Madagascar.
  • World Titanium Resources is developing the Tier 1 Toliara Sands Project north of the port of Toliara in south-west Madagascar. The Ranobe Mine  is projected to produce 407,000tpa of ilmenite and 44,000tpa of zircon rich concentrate per annum over an initial 21 year mine life. This first phase of development utilises around 17% of the 959 million tonne of Mineral Resource defined at Ranobe. The overall THM grade of 6.1% for the Ranobe Mineral Resource is high by minerals sands industry standards and the initial Ranobe mine plan focuses on an Ore Reserve of 161 million tonne averaging 8.2% THM, resulting in one of the highest in-situ ore values in the sector. With no overburden and very low slimes (<5%) simple dry mining can be utilised. The heavy mineral at Ranobe consists predominantly of ilmenite making up approximately 90% of the final products. The project also benefits significantly from the presence of much higher value zircon and rutile which, as a zircon rich concentrate, contribute about 10% of the product volume and around 45% of the projected revenue. The ilmenite and zircon rich concentrate can be easily separated from the ore utilising standard equipment and existing infrastructure can be leveraged to minimise the initial development capital. World Titanium Resources has a total exploration target of more than 4,700 million tonne in the Toliara Sands Exploration permits at Ranobe, Ankililoaka, Basibasy and Morombe, including the 959 million tonne at 6.1% THM Mineral Resource at Ranobe.

Uranium


Uranium mineralization occurs in the sediments of the Morondava Basin of western Madagascar, which consists of Karoo Supergroup continental sediments.
Uranium in the Tranomaro Zone, in southern Madagascar, typically occurs as uranothorianite hosted in north-south trending lineaments of pyroxenite.
  • Pan African Mining Corporation announced that it has been granted 36 additional research permits for uranium exploration in Madagascar. The permits were issued to the company’s subsidiary PAM Atomique Sarl (Pama), which is 20% owned by the Malagasy state. Pama’s uranium exploration programme is ongoing in the Antsirabe and Tranomaro Zones as part of the company’s joint venture (JV) with L’Office des Mines Nationales et des Industries Strategiques, a State agency. By virtue of the new permit grants, Pama’s overall uranium licences in Madagascar now number 46 research permits. The French Commissariat a l’Energie Atomique (CEA) exploited uranium from the regions of Folakara and Tranomaro during the period from the late 1930s through the 1950s, with systematic exploration of Madagascar for radioactive materials being undertaken to 1966 in detailed regional studies that outlined several uraniferous areas. In 1976, the newly created Omnis resumed exploration of the more promising CEA discoveries with technical advice and funding from the International Atomic Energy Agency and associated agencies. Pama is carrying forward such prior work as well as implementing innovative programmes conceived by its geological team working with Omnis.
  • Cline Mining Corporation has taken over UMC Energy plc, who has an 80% interest in URAMAD S.A., a Madagascar uranium exploration company. URAMAD S.A. is a private Madagascar uranium exploration company in which the Madagascar Government Agency OMNIS also holds a 20% interest. The URAMAD Morondava Uranium Project covers an area of 9,993.75 square kilometers in the Morondava Basin of western Madagascar, which is filled with Karoo Supergroup sediments. The uranium properties were earlier held by Cogema of France which carried out extensive exploration work, with additional work being carried forward by the United Nations Development Programme and OMNIS. URAMAD has obtained the databases from this work which include an extensive earlier airborne survey (some 7,000 radioactive anomalies) and 83,000 metres of drilling in 790 drill holes with indicated uranium values and visible uranium mineralization. URAMAD is presently undertaking an exploration program on the property including diamond drilling and radiometric airborne surveys.
Update on Sapphire Mining in Ilakaka-Sakaraha, Madagascar (GIA)

A parcel of sapphire and chrysoberyl from the Ilakaka-Sakaraha deposit in southern Madagascar. Photo by Vincent Pardieu.



A sapphire miner works with hand tools in the Taheza River at Analalava.

    The huge pit at Banque Suisse lies just a few hundred meters from the town of Ilakaka


    This large sapphire mining pit is being worked by about 150 people near Sakalama in the southeastern Ilakaka-Sakaraha region. This photo was taken just a few weeks after an interesting discovery led to a mini-rush


    A group of Malagasy miners works an open pit near Manombo Be.