Description
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AMIS0261 Au 1.12 g/t, Greenstone, Syama, Mali
Origin of Material: AMIS0261 is a commissioned CRM made from material sourced by SGS Minerals Services from the Syama Gold Mine which is run by Société Des Mines De Syama S.A (SOMISY), a company owned 80% by Resolute Mining Limited and 20% by the Republic of Mali. The mine is situated in south eastern Mali in West Africa, approximately 300km southeast of the capital Bamako and 30kms from the Côte d’Ivoire border.
The Syama mining permit straddles a major regional structure (the Syama shear), which can be traced over hundreds of kilometres southwards into Côte d’Ivoire. A number of gold occurrences, including Syama, lie adjacent to this NNE trending structure, which is believed to play an important role in controlling gold mineralisation in the region.
The mine was initially brought into production in 1990 by BHP, was purchased by Randgold Resources in 1996 and has produced over 1.5Moz of gold. The gold ore was mined using open cut methods and processed using a combination of “whole of ore” roasting and CIL extraction of gold from the roaster calcines. Following a sustained drop in the gold price during the late 1990’s, operations were suspended in early 2001 and the mine placed on care and maintenance. It has recently been brought back into production by the current owners.
The Project is located along a structural and geological feature known locally as the Syama Shear that extends for some 200km south into northern Côte d’Ivoire. Gold mineralisation is hosted within an overturned and thrusted basalt-metasediment package that is in contact (structural footwall) with a largely undeformed conglomeratic unit. Detailed structural studies at the Syama mine and nearby satellite ore bodies confirm that gold mineralisation is controlled by intersecting NNE trending reverse faults and NE trending thrusts, which envelope and bound the ore body in association with intense brecciation, sulphidation and carbonate alteration.
Mineral and Chemical Composition: The ore at Syama is located within highly altered (carbonate-silica-pyrite) mafic rocks. The gold mineralisation is very fine grained and often encapsulated in pyrite. The ore is hard, siliceous, abrasive, refractory and in places contains significant quantities of active carbonaceous material. Higher-grade ore is typically found in highly veined and fractured carbonate altered, intensely bleached and silicified basalt containing various quantities of abundant fine-grained and coarse-grained euhedral pyrite. Pyrite is typically observed as two phases, a very fine-grained disseminated phase, with a second much coarser-grained euhedral phase. Rare arsenopyrite has been observed within this unit, with occasional chalcopyrite. Carbonaceous material, probably graphite, is often observed as silicified fine 1mm thick wisps/veinlets, or as free carbon on fracture surfaces within drill core.
Recommended Concentrations and Limits
(at two Standard Deviations)
Au Pb Collection 1.12 ± 0.10 g/t
Cu M/ICP 86 ± 9 ppm
Specific Gravity 2.91 ± 0.08
