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Location: 66 km NW from Kuruman, South Africa
PO Box 187 Santoy Northern CapeSouth Africa8491
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Mining scale, mining and mill throughput capaciites.Full profiles of select mines and projects.
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Assmang is jointly managed by ARM and Assore. ARM provides the administration and technical services while Assore performs the sales and marketing function.
The manganese ores of the Kalahari Manganese Field are contained within sediments of the Hotazel Formation in the Postmasburg Group of the Griqualand West Sequence, a sub-division of the Proterozoic Transvaal Supergroup. The Griqualand West Sequence comprises a basal dolomite and banded ironstones dominating the Ghaap, Postmasburg and the Olifantshoek Groups. The Postmasburg Group consists of basal basaltic andesites of the Ongeluk lava and banded ironstone and manganese of the Hotazel Formation.On Belgravia, Santoy and Nchwaning farms the Hotazel Formation and overlying Mapedi shales and Lucknow quartzite sequences have been duplicated by thrusting. The thrusted orebodies were mined from surface at the Kalahari Manganese Field discovery outcrop, the Black Rock Koppie and at two other down dip interconnected Belgravia 1 and Belgravia 2 shafts. Mining reached depths of approximately 200 metres. The manganese resources hosted in the thrusted orebodies are reported, collectively, under Black Rock (Koppie area) orebodies. The average thickness of the HotazelFormation is approximately 75 metres, with the banded iron formation (BIF) hosted manganese orebodies occurring as three stratabound and stratiform units of variable thickness. The lowermost orebody (Seam 1) is of a higher grade in comparison to the topmost orebody (Seam 2). Seam 3, which occurs in between Seams 1 and 2, is thin and uneconomic.The manganese orebodies exhibit a complex mineralogy and more than 200 ore and gangue mineral species have been identified. Hydrothermal upgrading has resulted in zoning of the orebody adjacent to fault positions in most instances. Distal areas exhibit more original and lowgrade kutnohorite and braunite assemblages, while areas immediately adjacent to faults typically exhibit high-grade hausmannite rich ore. The intermediate areas exhibit mineralogy which includes bixbyite, braunite and jacobsite among a host of other manganese-bearing minerals. Similar zonation also exists in the vertical sense.At the top and bottom contacts it is common to have high iron (Fe) and low manganese (Mn) contents while the reverse is true towards the centre of the seam. This vertical zoning has given rise to a mining practice where only the 4.0 to 5.0-metre-high centre portion of the seam is being mined.
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