Specifications
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CRM State:
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Matrix:
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Mineralisation:
OREAS 293 has been prepared from underground sample material from the Ventersdorp Contact Reef (VCR). The material was provided by AngloGold Ashanti from the Mponeng Mine which is located 80 km west of Johannesburg in the West Wits mining district. The VCR is the youngest of the Witwatersrand palaeoplacers and comprises a gold bearing quartz pebble conglomerate preserved on a terraced unconformity surface and buried by the 2.7 Ga Ventersdorp Lava. The VCR and the footwall Witwatersrand sediments were modified (cooked) post burial by lower greenschist level hydrothermal metamorphism. This overprinting event remobilised some of the gold and pyrite within the conglomerate matrix; and deposited minor authigenic pyrrhotite, chalcopyrite, sphalerite and galena. These Reef samples were taken underground for grade control purposes and assayed. The pulp reject material was then sorted into different grade bins for the purposes of CRM manufacture. Barren quartz and granodiorite have been added to the pulps to achieve targeted CRM grades.
Thirty-four commercial analytical laboratories participated in the program to certify:
Analyte | Certified Value | 1SD | 95% Confidence Limits Low | 95% Confidence Limits High | Method |
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Au, Gold (ppb) | 72.5 | 4.73 | 71.1 | 74.0 | Pb Fire Assay |
Al2O3, Aluminium(III) oxide (wt.%) | 3.97 | 0.037 | 3.95 | 3.99 | Borate Fusion XRF |
BaO, Barium oxide (ppm) | 308 | 77 | 257 | 359 | Borate Fusion XRF |
CaO, Calcium oxide (wt.%) | 0.701 | 0.009 | 0.697 | 0.705 | Borate Fusion XRF |
Cr2O3, Chromium(III) oxide (ppm) | < 100 | IND | IND | IND | Borate Fusion XRF |
Fe2O3, Iron(III) oxide (wt.%) | 1.40 | 0.020 | 1.40 | 1.41 | Borate Fusion XRF |
K2O, Potassium oxide (wt.%) | 0.903 | 0.009 | 0.899 | 0.907 | Borate Fusion XRF |
MgO, Magnesium oxide (wt.%) | 0.338 | 0.015 | 0.330 | 0.346 | Borate Fusion XRF |
MnO, Manganese oxide (wt.%) | 0.015 | 0.004 | 0.013 | 0.017 | Borate Fusion XRF |
Na2O, Sodium oxide (wt.%) | 0.711 | 0.014 | 0.703 | 0.718 | Borate Fusion XRF |
P2O5, Phosphorus(V) oxide (wt.%) | 0.053 | 0.004 | 0.051 | 0.055 | Borate Fusion XRF |
S, Sulphur (wt.%) | 0.040 | 0.004 | 0.037 | 0.043 | Borate Fusion XRF |
SiO2, Silicon dioxide (wt.%) | 91.15 | 0.428 | 90.95 | 91.35 | Borate Fusion XRF |
TiO2, Titanium dioxide (wt.%) | 0.185 | 0.006 | 0.183 | 0.188 | Borate Fusion XRF |
Zn, Zinc (ppm) | 23.2 | 4.2 | 18.5 | 27.9 | Borate Fusion XRF |
Zr, Zirconium (ppm) | 68 | 14 | 56 | 81 | Borate Fusion XRF |
U, Uranium (ppm) | 2.40 | 0.115 | 2.33 | 2.47 | Borate / Peroxide Fusion ICP |
LOI1000, Loss On Ignition @1000°C (wt.%) | 0.241 | 0.092 | 0.191 | 0.291 | Thermogravimetry |
Ag, Silver (ppm) | 0.056 | 0.019 | 0.046 | 0.066 | 4-Acid Digestion |
Al, Aluminium (wt.%) | 2.07 | 0.038 | 2.05 | 2.08 | 4-Acid Digestion |
As, Arsenic (ppm) | 2.30 | 0.51 | 1.99 | 2.60 | 4-Acid Digestion |
Ba, Barium (ppm) | 273 | 12 | 269 | 278 | 4-Acid Digestion |
Be, Beryllium (ppm) | 0.73 | 0.049 | 0.70 | 0.76 | 4-Acid Digestion |
Bi, Bismuth (ppm) | 0.19 | 0.03 | 0.18 | 0.20 | 4-Acid Digestion |
Ca, Calcium (wt.%) | 0.506 | 0.015 | 0.500 | 0.512 | 4-Acid Digestion |
Cd, Cadmium (ppm) | 0.060 | 0.011 | 0.055 | 0.065 | 4-Acid Digestion |
Ce, Cerium (ppm) | 22.2 | 1.11 | 21.8 | 22.7 | 4-Acid Digestion |
Co, Cobalt (ppm) | 3.08 | 0.262 | 2.95 | 3.20 | 4-Acid Digestion |
Cr, Chromium (ppm) | 35.9 | 8.0 | 32.5 | 39.3 | 4-Acid Digestion |
Cs, Caesium (ppm) | 3.00 | 0.118 | 2.95 | 3.05 | 4-Acid Digestion |
Cu, Copper (ppm) | 10.7 | 0.83 | 10.3 | 11.0 | 4-Acid Digestion |
Dy, Dysprosium (ppm) | 1.20 | 0.13 | 1.10 | 1.30 | 4-Acid Digestion |
Er, Erbium (ppm) | 0.50 | 0.047 | 0.44 | 0.56 | 4-Acid Digestion |
Eu, Europium (ppm) | 0.40 | 0.013 | 0.39 | 0.41 | 4-Acid Digestion |
Fe, Iron (wt.%) | 0.973 | 0.031 | 0.961 | 0.985 | 4-Acid Digestion |
Ga, Gallium (ppm) | 5.45 | 0.367 | 5.30 | 5.61 | 4-Acid Digestion |
Gd, Gadolinium (ppm) | 1.81 | 0.103 | 1.75 | 1.87 | 4-Acid Digestion |
Hf, Hafnium (ppm) | 0.69 | 0.08 | 0.66 | 0.72 | 4-Acid Digestion |
Ho, Holmium (ppm) | 0.20 | 0.016 | 0.19 | 0.22 | 4-Acid Digestion |
In, Indium (ppm) | 0.019 | 0.003 | 0.018 | 0.020 | 4-Acid Digestion |
K, Potassium (wt.%) | 0.742 | 0.016 | 0.735 | 0.749 | 4-Acid Digestion |
La, Lanthanum (ppm) | 10.8 | 0.50 | 10.6 | 11.1 | 4-Acid Digestion |
Li, Lithium (ppm) | 27.1 | 1.56 | 26.5 | 27.7 | 4-Acid Digestion |
Lu, Lutetium (ppm) | 0.062 | 0.008 | 0.053 | 0.071 | 4-Acid Digestion |
Mg, Magnesium (wt.%) | 0.201 | 0.010 | 0.197 | 0.205 | 4-Acid Digestion |
Mn, Manganese (wt.%) | 0.010 | 0.000 | 0.010 | 0.011 | 4-Acid Digestion |
Mo, Molybdenum (ppm) | 1.94 | 0.128 | 1.90 | 1.98 | 4-Acid Digestion |
Na, Sodium (wt.%) | 0.526 | 0.028 | 0.513 | 0.538 | 4-Acid Digestion |
Nb, Niobium (ppm) | 3.62 | 0.207 | 3.52 | 3.72 | 4-Acid Digestion |
Nd, Neodymium (ppm) | 10.1 | 0.37 | 10.0 | 10.3 | 4-Acid Digestion |
Ni, Nickel (ppm) | 10.8 | 0.70 | 10.5 | 11.0 | 4-Acid Digestion |
P, Phosphorus (wt.%) | 0.022 | 0.001 | 0.022 | 0.023 | 4-Acid Digestion |
Pb, Lead (ppm) | 8.67 | 0.579 | 8.34 | 9.00 | 4-Acid Digestion |
Pr, Praseodymium (ppm) | 2.63 | 0.139 | 2.53 | 2.72 | 4-Acid Digestion |
Rb, Rubidium (ppm) | 45.4 | 2.37 | 44.4 | 46.5 | 4-Acid Digestion |
S, Sulphur (wt.%) | 0.040 | 0.002 | 0.040 | 0.041 | 4-Acid Digestion |
Sb, Antimony (ppm) | 0.24 | 0.023 | 0.23 | 0.25 | 4-Acid Digestion |
Sc, Scandium (ppm) | 2.36 | 0.208 | 2.24 | 2.48 | 4-Acid Digestion |
Sm, Samarium (ppm) | 2.05 | 0.169 | 1.96 | 2.15 | 4-Acid Digestion |
Sn, Tin (ppm) | 1.51 | 0.16 | 1.43 | 1.59 | 4-Acid Digestion |
Sr, Strontium (ppm) | 40.9 | 1.91 | 40.1 | 41.7 | 4-Acid Digestion |
Ta, Tantalum (ppm) | 0.32 | 0.025 | 0.31 | 0.34 | 4-Acid Digestion |
Tb, Terbium (ppm) | 0.25 | 0.012 | 0.24 | 0.26 | 4-Acid Digestion |
Te, Tellurium (ppm) | < 0.050 | IND | IND | IND | 4-Acid Digestion |
Th, Thorium (ppm) | 4.58 | 0.242 | 4.48 | 4.67 | 4-Acid Digestion |
Ti, Titanium (wt.%) | 0.109 | 0.005 | 0.107 | 0.110 | 4-Acid Digestion |
Tl, Thallium (ppm) | 0.26 | 0.010 | 0.25 | 0.26 | 4-Acid Digestion |
Tm, Thulium (ppm) | 0.066 | 0.012 | 0.044 | 0.087 | 4-Acid Digestion |
U, Uranium (ppm) | 2.26 | 0.190 | 2.19 | 2.32 | 4-Acid Digestion |
V, Vanadium (ppm) | 17.5 | 1.04 | 17.1 | 17.9 | 4-Acid Digestion |
W, Tungsten (ppm) | 2.27 | 0.24 | 2.20 | 2.34 | 4-Acid Digestion |
Y, Yttrium (ppm) | 4.78 | 0.381 | 4.60 | 4.95 | 4-Acid Digestion |
Yb, Ytterbium (ppm) | 0.44 | 0.08 | 0.39 | 0.49 | 4-Acid Digestion |
Zn, Zinc (ppm) | 22.3 | 1.65 | 21.6 | 22.9 | 4-Acid Digestion |
Zr, Zirconium (ppm) | 21.5 | 3.3 | 19.9 | 23.0 | 4-Acid Digestion |
S, Sulphur (wt.%) | 0.038 | 0.003 | 0.037 | 0.040 | Infrared Combustion |
SG, Specific Gravity (Unity) | 2.67 | 0.049 | 2.65 | 2.70 | Gas / Liquid Pycnometry |
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