Guinea. Economic analysis

Gold. First rumors about huge gold deposits in Mali date back to the beginning of last millennium. As of January 1st, 1998 total gold reserves in Mali count 820 tons, while the proved reserves make up 388 tons with average gold recovery of 3.9 grams/ton in primary deposits and 1.05 grams/m³ in placer deposits. 23 tons of gold were recovered in 1998. Due to the active geologic prospects and mine development gold recovery in Mali increased by more than 10 times in the last 10 years.
Year 1997 brought a drastic change to Mali gold mining: gold recovery sprang up to 18.5 tons (compare with 6.6 tons in 1996). It was the result of a French company's (SMOS - Societe d'exploitation des mines d'or Sadiola) debut on Sadiola deposit. In 1997 the new mine produced 13 tons of gold at a cost value of 3.3 dollars per gram. 4 mln tons of ore were also reprocessed here. The investment in the enterprise totaled 303 mln dollars.
Gold prospecting in the country dwindled to 2.2 tons in 1997 from 3 tons in 1996.
Almost all the gold deposits are located in the south-western part of the country, on the area of about 50 thousand sq. km. and are connected to Pre-Cambrian rock masses.
Impressing gold works were executed by Soviet specialists in 1961-1989. They found and explored Kalana deposit on the south of Mali. Here in the flat-dipping silicification zones and quartz veins prospected were 30 tons of gold with 15 grams/ton metal content in gold-arsenopyrite-pyrite-quartz ores. A considerable amount of recovered gold is in nuggets with prevailing grain size of 0.2 to 0.5 mm and purity of 800-900. The development of the deposit began in 1985. In 1995-1996 Kalana and Kodyeran deposits were re-prospected by foreign companies. The reserves reached, respectively, 40 tons with 6.1 grams/ton gold content and 52.5 tons with 2.3 grams/ton gold content.
In 1960s in the western part of Mali, on the right bank of Faleme river Soviet specialists prospected gold-bearing placers with 4.2 tons of gold reserve. More than 60 placers are now known in this region. The largest ones are developed by dredges. The length of alluvial placers is 1 to 8 km, their width - 20 to 200 meters, sand thickness - 0.4 to 2 meters, peat thickness - 2 to 11 meters, gold content in rock mass - 0.1 to 0.5 grams/m³, in layers - 0.5 - 4 grams/m³.
Gold works in Mali were especially active in the last decade. A remarkable increment of gold reserves was achieved in 1996 on the Sadyola formation in the western part of the country, in the northern part of Faleme region. Two companies, Anglo-American Group (South Africa) and IAM Gold (Canada) prospected 93 tons of gold with 2.2 grams/ton gold content in the sulfide ores here, lying 140-300 meters deep, right below the quarry under construction. In 1997 prospecting was done of 300-500 meters deep layers. The mineralization is represented by thick stockworks of quartz metasomatites belonging to the sand-schist Early Proterozoic rocks of the Birrim series.
In the Yatela formation, 455 bores were drilled, and th estimated gold reserves were assessed at 59 tons with 3 grams/ton recovery, in the Morila formation - 139 tons with 4.2 grams/ton gold recovery, in the Niaouleni the supposed reserves made up 30 tons.
In the southern part of Faleme region the abovementioned companies prospected a new deposit called Yali (30 tons of gold with 4.3 grams/ton recovery) and a deposit called Loulo (7.1 tons of gold). Total reserves in the stockwork quartz-tourmaline ores of Yali and Loulo deposits count 125 tons of gold with average gold content of 3.97 grams/ton.
A company called Syama Gold Mine, as part of Randgold Resources, prospected Syama deposit containing 135 tons of gold with 4 grams/ton gold recovery in the gold-sulfide-quartz ores.
In the northern regions of Kanieba province two companies, Oliver Gold Corp. and Nelson Resources, prospected Segala and Tabakoto deposits with respective gold reserves of 31 and 42 tons. Gold recovery in Tabakoto counts 7.5 grams/ton.
In 1992-1993 A joint Russian-American company Large International conducted prospects and exploration works on the Dialafara concession, 470 sq. km. in area, on the right bank of Faleme river, Kenieba province, western part of Mali. 4 placers (total gold - 650 kilograms) were prospected through bore pit drilling and placer sampling. Sand thickness - 0.6 to 1.2 meters, peat thickness - 5 to 6 meters, average gold content in the layer - 0.6 to 1.2 grams/m³. Test developments were executed in a number of placers. Despite serious expenses (more than 4 mln dollars), Large International and Gefest companies never managed to set up rentable placer development here because of sudden decrease in gold content in the deposit.
Drawing conclusions on the base of the Soviet and western geologic research, we can distinguish the following gold-bearing regions in Mali:
- Kanieba on the west of Mali, near Mali-Senegalese border: Loulo, Segala, Medinandi, Nali and Tabakoko deposits
- Kayes on the south-west of Mali, near the Mali-Guinean border: Sadiola deposit
- Kalana on the south, near the border with Guinea and Cote D'Ivoire: Kalana deposit
- Syama on the south-east, near the border with Burkina Faso: Syama deposit
- Kidal on the east, close to Sahara: Darset deposit.
On the whole, gold extraction in Mali made up (official information): 3,082 kilograms in 1992; 3,204 kilograms in 1993; 6,200 kilograms in 1994; 6,000 kilograms in 1995; 6,600 kilograms in 1996; 23,000 kilograms in 1998. It is worth noting, however, that these figures don't always reflect real extraction volumes. Different sources suggest that there's always a ton or two that the local prospectors extract without official statistics knowing it: the gold is sold straight to gold dealers who, in their turn, sell it to handicraftsmen or smuggle it abroad.

Phosphorites. In the Tilemsi river valley several phosphorite deposits were found: Tamagel, Tina-Hina, Tamagoulelt, Samit. Ore bodies are located in the mass of Eocene clays and marls. The visible thickness of phosphorites varies between 2 and 10 meters. The phosphorites are characterized by high iron and alumina content. Total reserves are assessed at 25 mln tons with average phosphoric anhydride content counting 27%. In the present time, phosphorite extraction takes place in Tilemsi region. Extraction volumes - approximately 240,000 tons a year.

Uranium. In the north-west of Mali, in the region of Archean - Lower Proterozoic metamorphic rocks development (Adrar-Ifaras rock mass), a number of uranium mineralization sectors were detected: Kidal, Tessalit and other. Total uranium reserves here are circa 100,000 tons.

Diamonds. 70 sizeable diamonds were found in the Kenieba region in early 1980s. Among them was Mali's biggest ever diamond of 232 carats. 16 kimberlite pipes were explored, 5 of them turned out diamond-bearing: Sekonomato, Tzirk, Missiya, Bilani and Orange River. The pipes are located in the Early Proterozoic sedimentations and Ordovician sandstones that cover them. Supposed reserves are assessed at 10 mln carats.