OREAS 629

OREAS 629 was prepared from a blend of Zn-Pb-Cu-Ag-Au bearing ores and concentrates from MMG’s Rosebery operation on the west coast of Tasmania, Australia and barren rhyodacite rock sourced from a quarry east of Melbourne, Australia. The key minerals of economic importance include sphalerite, galena, chalcopyrite (minor tetrahedrite) and electrum. Gold occurs as free electrum and also as inclusions within sulphides; silver occurs within tetrahedrite and galena. Pyrite, quartz, silicates, barite, mangano carbonate, pyrrhotite and magnetite form the main gangue minerals (Denwer et al., 2017. Rosebery Cu-Pb-Zn-Ag-Au volcanogenic massive sulfide deposit, in Australian Ore Deposits (ed: G N Phillips), pp 817-821 (The Australian Institute of Mining and Metallurgy; Melbourne). Twenty eight commercial analytical laboratories participated in the characterisation program to certify the elements reported below.

• Gold by 25-40g fire assay with ICP or AAS finish;
• Gold by 15-50g aqua regia digestion with ICP-OES, ICP-MS, AAS or graphite furnace AAS finish;
• Full ICP-OES and ICP-MS elemental suites by peroxide fusion;
• Full ICP-OES and ICP-MS elemental suites by 4-acid digestion (HF-HNO3-HClO4-HCl);
• Full ICP-OES and ICP-MS elemental suites by aqua regia digestion;
• A limited suite of elements by 3-acid digestion (HNO3-HCIO4-HCI) with ICP-OES or AAS finish;
• Sulphur by infrared combustion analysis;
• Homogeneity evaluation of Au using instrumental neutron activation analysis (INAA) on 20 x 85mg subsamples (undertaken by ANSTO, Lucas Heights).