OREAS 293
SKU: 293
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:
Gold by fire assay;
Major and trace elements by borate fusion with XRF;
Uranium by fusion with ICP-MS;
Full ICP-OES and ICP-MS elemental suites by borate and peroxide fusion;
Full ICP-OES and ICP-MS elemental suites by 4-acid digestion;
Specific gravity by gas and liquid pycnometry;
Total Sulphur by infrared combustion furnace.
Specifications
- State: primary
- Matrix: quartz conglomerate
- Mineralisation: modified paleoplacer
- CRM Group: Au
Certified Values
| Analyte | Certified Value | 1SD | 95% CL Low | 95% CL High | Method |
|---|---|---|---|---|---|
| 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 |
Product Specifications
Certified Reference Values
| Analyte | Certified Value | Uncertainty (1SD) | 95% Confidence Low | 95% Confidence High | Method |
|---|---|---|---|---|---|
| Ce - Cerium (ppm) | 22.2 | - | - | - | 4-Acid Digestion |
| Dy - Dysprosium (ppm) | 1.20 | - | - | - | 4-Acid Digestion |
| Er - Erbium (ppm) | 0.50 | - | - | - | 4-Acid Digestion |
| Eu - Europium (ppm) | 0.40 | - | - | - | 4-Acid Digestion |
| Gd - Gadolinium (ppm) | 1.81 | - | - | - | 4-Acid Digestion |
| Ho - Holmium (ppm) | 0.20 | - | - | - | 4-Acid Digestion |
| La - Lanthanum (ppm) | 10.8 | - | - | - | 4-Acid Digestion |
| Lu - Lutetium (ppm) | 0.062 | - | - | - | 4-Acid Digestion |
| Nd - Neodymium (ppm) | 10.1 | - | - | - | 4-Acid Digestion |
| Pr - Praseodymium (ppm) | 2.63 | - | - | - | 4-Acid Digestion |
| Sm - Samarium (ppm) | 2.05 | - | - | - | 4-Acid Digestion |
| Tb - Terbium (ppm) | 0.25 | - | - | - | 4-Acid Digestion |
| Tm - Thulium (ppm) | 0.066 | - | - | - | 4-Acid Digestion |
| Y - Yttrium (ppm) | 4.78 | - | - | - | 4-Acid Digestion |
| Yb - Ytterbium (ppm) | 0.44 | - | - | - | 4-Acid Digestion |
SD = Standard Deviation | CL = 95% Confidence Limits
Methods: AR = Aqua Regia, 4-Acid = 4-Acid Digestion, LBF = Lithium Borate Fusion, FA/AAS = Fire Assay with Atomic Absorption, LECO = LECO Combustion Analysis
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