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Syama |
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Mali |
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Au
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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The Syama gold mine is located in southern Mali, 300 km SE of Bamako and within 25 km of the Ivory Coast border (#Location: 10° 47' 22"N, 6° 17' 4"W).
Ancient mining dating to around 1200 AD is recorded at Syama, when gold was extracted from extensive shallow workings in the oxide zone. During the 1960's and 1970's exploration was carried out to investigate the placer potential of the area. This work was undertaken by the Bureau de Recherche et Geologie Minère and the Société Nationale de Recherche Minère of Mali. The UNDP, with the Direction Nationale de la Geologie et des Mines of Mali, carried out regional soil sampling in 1980 and indicated anomalous gold values in soils. Subsequently the UNDP undertook a program of shallow pitting and indicated an oxide resource of 1.5 Mt @ 1.67 g/t Au. BHP-Utah Minerals International entered into a joint venture agreement with the Mali Government in 1987 to undertake further exploration. A total of 18 000 m of core drilling was completed between 1988 and 1990 (Olson, etal., 1992). The drilling program, which was completed during construction in 1989, identified a large sulphide orebody below the oxide workings (AME, 1994).
The gold mineralisation at Syama lies within a major reverse fault zone on the margin of Birimian volcanic/greenstone belt in southern Mali. This volcanic belt is a thin (0.5 to 2 km wide), but regionally extensive sequence of basalt and andesite with interbedded greywacke and argillite, and andesite-lamprophyre intrusives. It is bounded to the east by andesitic conglomerate and greywacke, and to the west by interbedded greywacke and argillite. In the Syama area this ore bearing sequence is structurally layered, overturned and east vergent. Massive competent basalt and conglomerate bound the hangingwall and footwall of the mineralised interval respectively (Olson, etal., 1992).
Lateritic/saprolitic weathering developed an oxide orebody that overlies the sulphide mineralisation. This oxide ore extends for 35 to 40 m below the surface, while the sulphide mineralisation has been tested to a depth of 500 m (Olson, etal., 1992).
The sulphide ore consists of lenticular bodies of intense ankerite-quartz veinlet stockworks, zones of sheeted ankerite-quartz veinlets and breccia bodies. The pyritic quartz-ankerite veining is largely restricted to high pyrite (>7 to 10%) zones. Breccias and intense stockwork zones host most of the higher grade (>4 g/t Au) ore. Sheeted veins are spaced at a density of more than 5/m and are 1 to 10 mm thick. Pyrite is the principal gold bearing mineral and occurs disseminated in veinlet halos and breccia clasts. Gold occurs as sub-micron to visible inclusions in and around the edges of pyrite crystals and as free gold. Green chloritic basalt is the preferred, but not exclusive, host of the mineralisation. The basalt is commonly bleached by ankerite, albite and sericite alteration in the pyritic gold bearing zones. Andesitic-lamprophyric intrusives and greywacke-argillite layers also host mineralisation. Within the intrusives, low grade ore occurs as weak stockworks of quartz-ankerite veins, while the sediments mainly hosts disseminated sulphides and fine quartz-ankerite stockworks. Faulted beds of graphitic greywacke-argillite and zones of silicification bound most individual ore lenses (Olson, etal., 1992).
Published reserve and resource figures include:
Mineable oxide Reserve, 1990 - 3 Mt @ 3.2 g/t Au = 9.6 t Au (Olson, et al., 1992).
Sulphide Reserve to 320 m, 1990 - 21 Mt @ 4.02 g/t Au = 84 t Au (Olson, et al., 1992).
Syama (at 1 g/t Au cutoff - reserves are exclusive of resources - Resolute Mining Ltd ore reserve statement, 2014)
Proved reserve, 30 June, 2014 - 9.026 Mt @ 2.9 g/t Au = 26.2 t Au
Probable reserve, 30 June, 2014 - 2.955 Mt @ 2.6 g/t Au = 7.6 t Au
Measured resource, 30 June, 2014 - 6.900 Mt @ 2.4 g/t Au = 16.3 t Au
Indicated resource, 30 June, 2014 - 12.482 Mt @ 2.9 g/t Au = 35.9 t Au
Inferred resource, 30 June, 2014 - 3.403 Mt @ 2.3 g/t Au = 7.8 t Au
Syama Underground (at 1.8 g/t Au cutoff - reserves are exclusive of resources - Resolute Mining Ltd ore reserve statement, 2014)
Probable reserve, 30 June, 2014 - 14.296 Mt @ 2.4 g/t Au = 34.3 t Au
Syama Satellites (at 1 g/t Au cutoff - reserves are exclusive of resources - Resolute Mining Ltd ore reserve statement, 2014)
Proved reserve, 30 June, 2014 - 3.122 Mt @ 2.2 g/t Au = 6.9 t Au
Probable reserve, 30 June, 2014 - 4.986 Mt @ 2.1 g/t Au = 10.4 t Au
Measured resource, 30 June, 2014 - 1.051 Mt @ 1.7 g/t Au = 1.8 t Au
Indicated resource, 30 June, 2014 - 4.840 Mt @ 1.9 g/t Au = 9.1 t Au
Inferred resource, 30 June, 2014 - 6.946 Mt @ 2.1 g/t Au = 14.9 t Au
JORC compliant Mineral Resources and Ore Reserves as at 31 December, 2023 at a 1.5 g/t Au cutoff (Resolute Mining Ore Reserve and Mineral Resources Statement, 2023):
Syama Underground
Measured Resource - 24.023 Mt @ 3.1 g/t Au;
Indicated Resource - 24.940 Mt @ 2.6 g/t Au;
Inferred Resource - 1.903 Mt @ 2.0 g/t Au.
SUB TOTAL Resources (underground) - 50.866 Mt @ 2.8 g/t Au.
Proved + Probable Reserves - 23.588 Mt @ 2.5 g/t Au.
Syama Stockpiles
Measured Resource - 1.071 Mt @ 1.8 g/t Au;
Indicated Resource - 1.777 Mt @ 1.3 g/t Au;
SUB TOTAL Resources (stockpiles) - 2.848 Mt @ 1.5 g/t Au.
Proved + Probable Reserves - 2.894 Mt @ 1.5 g/t Au.
TOTAL RESOURCES (Syama Underground + Stockpiles) - 53.714 Mt @ 2.7 g/t Au, for ~147 tonnes of contained gold.
Syama Satellites
Measured Resource - 3.448 Mt @ 2.8 g/t Au;
Indicated Resource - 30.032 Mt @ 2.8 g/t Au;
Inferred Resource - 12.783 Mt @ 2.5 g/t Au.
SUB TOTAL Resources (Syama satellites) - 46.263 Mt @ 2.7 g/t Au.
Proved + Probable Reserves - 13.234 Mt @ 2.5 g/t Au.
Syama Satellite Stockpiles
Measured resource - 1.848 Mt @ 1.4 g/t Au;
Indicated resource - 1.449 Mt @ 1.0 g/t Au;
Inferred Resource - 0.046 Mt @ 1.1 g/t Au.
SUB TOTAL Resources (Syama Satellites and Stockpiles) - 15.556 Mt @ 2.3 g/t Au.
Proved + Probable Reserves - 2.322 Mt @ 1.2 g/t Au.
TOTAL RESOURCES (Syama Satellites + Stockpiles) - 49.606 Mt @ 2.6 g/t Au, for ~129 tonnes of contained gold.
NOTE: In the 2023 estimates, resources are inclusive of reserves.
For detail consult the reference(s) listed below.
The most recent source geological information used to prepare this decription was dated: 1994.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
Syama
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Olson S F, Diakite K, Ott L, Guindo A, Ford C R B, Winer N, Hanssen E, Lay N, Bradley R, Pohl D 1992 - Regional setting, structure, and descriptive geology of the Middle Proterozoic Syama Gold deposit, Mali, west Africa: in Econ. Geol. v87 pp 310-331
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