Description
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Origin of Material
The standard was made using material from the Ventersdorp Conatct 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
(at two Standard Deviations)
Certified Concentrations
Analyte Method 6(µ) 8 (2s) ± Unit
Au 1Pb Collection 2.93 0.41 g/t
U 24A_MICP 96 5 ppm
U 3XRF 93 6 ppm
LOI 4LOI 1.41 0.11 %
S 5Combustion/LECO 0.38 0.04 %
Al 4A_MICP 3.99 0.44 %
As 4A_MICP 49 6 ppm
Ba 4A_MICP 283 30 ppm
Be 4A_MICP 0.8 0.4 ppm
Ca 4A_MICP 886 133 ppm
Ce 4A_MICP 44 3 ppm
Co 4A_MICP 20 1 ppm
Cu 4A_MICP 48 7 ppm
Fe 4A_MICP 1.06 0.079 %
K 4A_MICP 1.40 0.15 %
La 4A_MICP 22 3 ppm
Li 4A_MICP 6 0.4 ppm
Mg 4A_MICP 983 132 ppm
Mn 4A_MICP 85 16 ppm
Mo 4A_MICP 4 2 ppm
Ni 4A_MICP 55 7 ppm
Pb 4A_MICP 56 16 ppm
Rb 4A_MICP 57 7 ppm
Sr 4A_MICP 24 5 ppm
Th 4A_MICP 14 0.9 ppm
V 4A_MICP 28 3 ppm
Zn 4A_MICP 26 2 ppm
Zr 4A_MICP 57 3 ppm
Major Oxides
Certified Concentrations (at two Standard Deviations)
Analyte Method 6(µ) 8 (2s) ± Unit
U3O3 XRF 0.010 0.0006
U3O8 4A_MICP 0.011 0.0006
U3O8 XRF 0.011 0.0007
Fe2O3 XRF 1.48 0.052
K2O XRF 1.73 0.10
MnO XRF 0.011 0.00
SiO2 XRF 85.68 3.1
TiO2 XRF 0.21 0.02
