OREAS 236

OREAS 236 was prepared from a blend of gold ore and barren greenstone. The ore was sourced from the Frogs Leg Gold Mine located 19km west of Kalgoorlie in Western Australia. The Cambrian greenstone was sourced from a quarry 145km north of Melbourne, Australia.
Thirty-one commercial analytical laboratories participated in the program to certify the elements reported below.

  • Gold by fire assay (25-50g charge weight) with AAS and ICP-OES finish;
  • Gold by aqua regia digestion (15-50g sample weight) with ICP-OES and/or ICP-MS finish;
  • Gold by cyanide leach (20-200g) with AAS or ICP-MS finish;
  • Gold by x-ray photon assay on ~350g sample weights (12 Chrysos PhotonAssay units at 7 laboratories with two rounds of data reported from each unit);
  • Full ICP-OES and ICP-MS elemental suites by 4-acid digestion;
  • Full ICP-OES and ICP-MS elemental suites by aqua regia digestion.

To confirm homogeneity, gold by instrumental neutron activation analysis (INAA) was undertaken on 20 x 85mg subsamples (see Table 5 in the ‘Homogeneity Evaluation’ of the Certificate).

Analyte Certified Value 1SD Expanded Uncertainty Low Expanded Uncertainty High Method
Au, Gold (ppm) 1.85 0.059 1.83 1.87 Pb Fire Assay
Au, Gold (ppm) 1.75 0.087 1.71 1.79 Aqua Regia Digestion (sample weights 10-50g)
Au, Gold (ppm) 1.79 0.048 1.77 1.82 Cyanide Leach
Au, Gold (ppm) 1.85 0.053 1.83 1.87 PhotonAssay
Ag, Silver (ppm) 0.478 0.058 0.433 0.524 4-Acid Digestion
Al, Aluminium (wt.%) 6.59 0.152 6.45 6.74 4-Acid Digestion
As, Arsenic (ppm) 68 4.0 65 71 4-Acid Digestion
Ba, Barium (ppm) 246 9 239 253 4-Acid Digestion
Be, Beryllium (ppm) 0.46 0.029 0.43 0.49 4-Acid Digestion
Bi, Bismuth (ppm) 0.061 0.007 0.053 0.070 4-Acid Digestion
Ca, Calcium (wt.%) 5.93 0.246 5.78 6.09 4-Acid Digestion
Cd, Cadmium (ppm) 0.62 0.044 0.58 0.67 4-Acid Digestion
Ce, Cerium (ppm) 14.0 1.36 13.1 14.8 4-Acid Digestion
Co, Cobalt (ppm) 41.5 2.36 40.2 42.8 4-Acid Digestion
Cr, Chromium (ppm) 86 4.3 83 90 4-Acid Digestion
Cs, Caesium (ppm) 1.01 0.072 0.93 1.09 4-Acid Digestion
Cu, Copper (ppm) 170 6 165 174 4-Acid Digestion
Dy, Dysprosium (ppm) 3.94 0.264 3.70 4.18 4-Acid Digestion
Er, Erbium (ppm) 2.43 0.154 2.29 2.57 4-Acid Digestion
Eu, Europium (ppm) 0.96 0.030 0.91 1.01 4-Acid Digestion
Fe, Iron (wt.%) 8.00 0.273 7.79 8.22 4-Acid Digestion
Ga, Gallium (ppm) 16.1 1.6 15.2 17.1 4-Acid Digestion
Gd, Gadolinium (ppm) 3.47 0.230 3.23 3.72 4-Acid Digestion
Hf, Hafnium (ppm) 1.80 0.081 1.68 1.92 4-Acid Digestion
Ho, Holmium (ppm) 0.86 0.032 0.81 0.91 4-Acid Digestion
In, Indium (ppm) 0.080 0.008 0.071 0.088 4-Acid Digestion
K, Potassium (wt.%) 0.559 0.019 0.540 0.578 4-Acid Digestion
La, Lanthanum (ppm) 5.99 0.462 5.67 6.30 4-Acid Digestion
Li, Lithium (ppm) 10.5 0.61 10.1 10.9 4-Acid Digestion
Lu, Lutetium (ppm) 0.37 0.028 0.34 0.40 4-Acid Digestion
Mg, Magnesium (wt.%) 3.40 0.104 3.32 3.48 4-Acid Digestion
Mn, Manganese (wt.%) 0.133 0.007 0.129 0.138 4-Acid Digestion
Mo, Molybdenum (ppm) 1.56 0.19 1.43 1.69 4-Acid Digestion
Na, Sodium (wt.%) 2.15 0.056 2.09 2.22 4-Acid Digestion
Nb, Niobium (ppm) 3.63 0.282 3.40 3.86 4-Acid Digestion
Nd, Neodymium (ppm) 9.01 0.462 8.56 9.47 4-Acid Digestion
Ni, Nickel (ppm) 68 4.3 66 71 4-Acid Digestion
P, Phosphorus (wt.%) 0.045 0.003 0.044 0.047 4-Acid Digestion
Pb, Lead (ppm) 30.5 1.99 29.1 31.8 4-Acid Digestion
Pr, Praseodymium (ppm) 1.94 0.101 1.79 2.09 4-Acid Digestion
Rb, Rubidium (ppm) 14.1 0.83 13.4 14.7 4-Acid Digestion
Re, Rhenium (ppm) 0.003 0.001 0.001 0.004 4-Acid Digestion
S, Sulphur (wt.%) 0.444 0.017 0.430 0.458 4-Acid Digestion
Sb, Antimony (ppm) 1.76 0.147 1.65 1.88 4-Acid Digestion
Sc, Scandium (ppm) 38.5 1.91 37.2 39.8 4-Acid Digestion
Se, Selenium (ppm) < 5.00 IND IND IND 4-Acid Digestion
Sm, Samarium (ppm) 2.71 0.171 2.47 2.94 4-Acid Digestion
Sn, Tin (ppm) 1.08 0.13 0.95 1.22 4-Acid Digestion
Sr, Strontium (ppm) 95 4.9 92 98 4-Acid Digestion
Ta, Tantalum (ppm) 0.25 0.03 0.22 0.27 4-Acid Digestion
Tb, Terbium (ppm) 0.62 0.036 0.57 0.66 4-Acid Digestion
Te, Tellurium (ppm) 0.11 0.02 0.09 0.14 4-Acid Digestion
Th, Thorium (ppm) 1.10 0.11 1.02 1.18 4-Acid Digestion
Ti, Titanium (wt.%) 0.639 0.026 0.619 0.658 4-Acid Digestion
Tl, Thallium (ppm) 0.24 0.018 0.23 0.26 4-Acid Digestion
Tm, Thulium (ppm) 0.36 0.022 0.33 0.39 4-Acid Digestion
U, Uranium (ppm) 0.35 0.04 0.31 0.38 4-Acid Digestion
V, Vanadium (ppm) 279 15 269 290 4-Acid Digestion
W, Tungsten (ppm) 30.5 1.43 29.4 31.7 4-Acid Digestion
Y, Yttrium (ppm) 21.7 0.85 21.0 22.4 4-Acid Digestion
Yb, Ytterbium (ppm) 2.32 0.152 2.18 2.47 4-Acid Digestion
Zn, Zinc (ppm) 144 6 139 148 4-Acid Digestion
Zr, Zirconium (ppm) 55 3.9 52 57 4-Acid Digestion
Ag, Silver (ppm) 0.488 0.029 0.460 0.515 Aqua Regia Digestion
Al, Aluminium (wt.%) 3.16 0.167 3.04 3.27 Aqua Regia Digestion
As, Arsenic (ppm) 67 3.4 64 69 Aqua Regia Digestion
B, Boron (ppm) 90 6.9 84 97 Aqua Regia Digestion
Ba, Barium (ppm) 35.7 2.94 33.8 37.5 Aqua Regia Digestion
Be, Beryllium (ppm) 0.26 0.020 0.24 0.29 Aqua Regia Digestion
Bi, Bismuth (ppm) 0.062 0.006 0.055 0.069 Aqua Regia Digestion
Ca, Calcium (wt.%) 2.64 0.209 2.52 2.75 Aqua Regia Digestion
Cd, Cadmium (ppm) 0.61 0.031 0.58 0.65 Aqua Regia Digestion
Ce, Cerium (ppm) 10.6 0.39 10.3 11.0 Aqua Regia Digestion
Co, Cobalt (ppm) 30.8 2.21 29.5 32.1 Aqua Regia Digestion
Cr, Chromium (ppm) 32.8 1.81 31.5 34.1 Aqua Regia Digestion
Cs, Caesium (ppm) 0.73 0.023 0.70 0.75 Aqua Regia Digestion
Cu, Copper (ppm) 169 6 165 174 Aqua Regia Digestion
Dy, Dysprosium (ppm) 2.58 0.204 2.30 2.86 Aqua Regia Digestion
Er, Erbium (ppm) 1.52 0.16 1.29 1.76 Aqua Regia Digestion
Eu, Europium (ppm) 0.58 0.08 0.47 0.69 Aqua Regia Digestion
Fe, Iron (wt.%) 5.95 0.217 5.80 6.10 Aqua Regia Digestion
Ga, Gallium (ppm) 11.6 0.69 11.1 12.1 Aqua Regia Digestion
Gd, Gadolinium (ppm) 2.24 0.142 2.02 2.47 Aqua Regia Digestion
Ge, Germanium (ppm) 0.15 0.02 0.12 0.17 Aqua Regia Digestion
Hf, Hafnium (ppm) 0.54 0.045 0.50 0.58 Aqua Regia Digestion
Hg, Mercury (ppm) 0.046 0.012 0.034 0.059 Aqua Regia Digestion
Ho, Holmium (ppm) 0.53 0.06 0.44 0.61 Aqua Regia Digestion
In, Indium (ppm) 0.039 0.003 0.032 0.045 Aqua Regia Digestion
K, Potassium (wt.%) 0.134 0.008 0.128 0.141 Aqua Regia Digestion
La, Lanthanum (ppm) 4.72 0.262 4.53 4.92 Aqua Regia Digestion
Li, Lithium (ppm) 9.28 0.440 8.93 9.63 Aqua Regia Digestion
Lu, Lutetium (ppm) 0.18 0.017 0.16 0.20 Aqua Regia Digestion
Mg, Magnesium (wt.%) 1.72 0.049 1.69 1.76 Aqua Regia Digestion
Mn, Manganese (wt.%) 0.071 0.004 0.069 0.074 Aqua Regia Digestion
Mo, Molybdenum (ppm) 1.49 0.071 1.42 1.56 Aqua Regia Digestion
Na, Sodium (wt.%) 0.265 0.017 0.255 0.275 Aqua Regia Digestion
Nb, Niobium (ppm) 0.16 0.05 0.12 0.20 Aqua Regia Digestion
Nd, Neodymium (ppm) 6.89 0.326 6.40 7.37 Aqua Regia Digestion
Ni, Nickel (ppm) 48.8 3.29 46.9 50.8 Aqua Regia Digestion
P, Phosphorus (wt.%) 0.045 0.001 0.043 0.046 Aqua Regia Digestion
Pb, Lead (ppm) 30.5 2.06 29.2 31.7 Aqua Regia Digestion
Pr, Praseodymium (ppm) 1.43 0.130 1.24 1.61 Aqua Regia Digestion
Rb, Rubidium (ppm) 5.87 0.428 5.55 6.19 Aqua Regia Digestion
Re, Rhenium (ppm) 0.002 0.000 0.001 0.003 Aqua Regia Digestion
S, Sulphur (wt.%) 0.445 0.025 0.429 0.462 Aqua Regia Digestion
Sb, Antimony (ppm) 0.90 0.31 0.74 1.06 Aqua Regia Digestion
Sc, Scandium (ppm) 6.47 0.66 6.03 6.92 Aqua Regia Digestion
Se, Selenium (ppm) < 1.00 IND IND IND Aqua Regia Digestion
Sm, Samarium (ppm) 1.89 0.184 1.65 2.12 Aqua Regia Digestion
Sn, Tin (ppm) 0.68 0.049 0.62 0.75 Aqua Regia Digestion
Sr, Strontium (ppm) 29.7 2.67 28.2 31.3 Aqua Regia Digestion
Ta, Tantalum (ppm) < 0.010 IND IND IND Aqua Regia Digestion
Tb, Terbium (ppm) 0.39 0.021 0.36 0.41 Aqua Regia Digestion
Te, Tellurium (ppm) 0.11 0.01 0.09 0.12 Aqua Regia Digestion
Th, Thorium (ppm) 0.88 0.057 0.81 0.95 Aqua Regia Digestion
Ti, Titanium (wt.%) 0.387 0.061 0.356 0.418 Aqua Regia Digestion
Tl, Thallium (ppm) 0.13 0.009 0.12 0.14 Aqua Regia Digestion
Tm, Thulium (ppm) 0.20 0.02 0.17 0.22 Aqua Regia Digestion
U, Uranium (ppm) 0.24 0.014 0.23 0.25 Aqua Regia Digestion
V, Vanadium (ppm) 158 10 152 165 Aqua Regia Digestion
W, Tungsten (ppm) 22.6 2.9 20.6 24.6 Aqua Regia Digestion
Y, Yttrium (ppm) 12.9 0.84 12.4 13.5 Aqua Regia Digestion
Yb, Ytterbium (ppm) 1.29 0.13 1.13 1.45 Aqua Regia Digestion
Zn, Zinc (ppm) 133 7 129 137 Aqua Regia Digestion
Zr, Zirconium (ppm) 17.8 2.1 16.5 19.2 Aqua Regia Digestion
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