Description
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Origin of Material
The standard was made using material from the Ventersdorp Contact Reef of the Witwatersrand Basin.
Approximate Mineral and Chemical Composition
Throughout the Witwatersrand, gold ores occur in sheets or reefs originally deposited horizontally under water. The thickness of the reefs range between a lie of grit to several meters, with an average of 300mm. The sediments were also intersected by dykes and sills of dolomite, diabase and syenite intruding existing faults. The reefs can be in the form of either course conglomerates, rock pebbles and cemented in a silicate matrix. Pebbles usually derived from vein quarts, may also consist of quarzitic, chert jasper and quartz porphyry. The matrix consists of pure silica, but also contains minute flakes of muscovite and pyrophyllite as well as visible pyrite and other sulphides. The gold is usually confined to the matrix and tends to be concentrated along bedding planes (Vermeulen, 2001).
Recommended Concentrations and Limits
Certified Concentrations (at two Standard Deviations)
Au Pb Collection 0.395 0.089 g/t
U 4A_MICP 87 11 ppm
U XRF 89 20 ppm
S Combustion/LECO 0.96 0.04 %
S 4A_MICP 0.93 0.04 %
SG SG 2.76 0.019 Dimensionless
Al 4A_MICP 4.53 0.086 %
As 4A_MICP 132 14 ppm
Ba 4A_MICP 329 27 ppm
Be 4A_MICP 1 0.4 ppm
Ca 4A_MICP 9585 530 ppm
Co 4A_MICP 48 5 ppm
Cu 4A_MICP 84 5 ppm
Fe 4A_MICP 2.61 0.079 %
Ga 4A_MICP 10 0.6 ppm
K 4A_MICP 1.44 0.073 %
La 4A_MICP 44 5 ppm
Li 4A_MICP 9 1 ppm
Mg 4A_MICP 2689 254 ppm
Mn 4A_MICP 1317 95 ppm
Mo 4A_MICP 3 0.9 ppm
Na 4A_MICP 1774 78 ppm
Ni 4A_MICP 126 11 ppm
Pb 4A_MICP 148 10 ppm
Sc 4A_MICP 5 1 ppm
Sr 4A_MICP 59 6 ppm
V 4A_MICP 38 10 ppm
Y 4A_MICP 15 4 ppm
Zn 4A_MICP 172 21 ppm
