Description
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AMIS0486 PGM 4E 4.16 g/t Merensky South Africa
Origin of Material
Although the Merensky generally regarded as a uniform reef type, the large variations occur in reef thickness, reef composition, as well as the position of the mineralisation. The rock forming minerals of the Merensky reef comprises approximately equal amounts of dark iron-magnesium silicate minerals and lighter calcium-aluminium-sodium silicate minerals under and overlain by thin often discontinuous layers of chromite concentratons. This zone, commonly known as the Merensky pegmatoid, contains the base metal sulphide grains and associated platinum group minerals. The Merensky reef has been traced for 300km around the entire outcrop of the eastern and western limbs of the Bushveld Complex, and to depths of 5km (Schouwstra, et.al, 2000).
Approximate Mineral and Chemical Composition
The rock forming silicate minerals of the Merensky reef consist predominantly of orthopy-roxene (60%, plagioclase feldspar (20%), pyroxene (15%), phlogopite (5%) and occasional olivine. Secondary minerals such as talc,serpentine,chlorite and magnetite have widespread occurrence. The base metal sulfides consist of pyrrhotite (40%), pentlandite (30%), chalcopyrite (15%) and trace amounts of millerite (NiS), troilite (FeS), pyrite (FeS2) and cubanite (Cu5FeS4). The major platinum group mineras are coperite (PtS), braggite [(Pt,pd)NiS], sperrylite (PtAs2) and PGE alloys, although in some areas minerals such as laurite (RuS2) can be abundant (Schouwstra, et.al, 2000).
Recommended Concentrations and Limits
(at two Standard Deviations)
Certified Concentrations
Analyte
Au Pb Collection 0.23 0.04 g/t
Pt Pb Collection 2.38 0.14 g/t
Pd Pb Collection 1.37 0.10 g/t
Au NiS 0.22 0.03 g/t
Pt NiS 2.34 0.19 g/t
Pd NiS 1.37 0.15 g/t
Rh NiS 0.23 0.02 g/t
Ir NiS 0.079 0.02 g/t
Ru NiS 0.37 0.06 g/t
Co 4A_MICP 149 20 ppm
Co FUS 161 23 ppm
Cr XRF 7321 274 ppm
Cu 4A_MICP 588 34 ppm
Cu FUS 584 41 ppm
Cu XRF 565 97 ppm
Ni 4A_MICP 2037 204 ppm
Ni FUS 2024 120 ppm
S 4A_MICP 0.30 0.02 %
S Comb/LECO 0.29 0.05 %
SG SG 3.34 0.14 Dimensionless
