OREAS 993 was prepared from a copper-gold-silver concentrate sample supplied by Newcrest Mining Limited’s Cadia Valley Operations near Orange, New South Wales, Australia. Ten ‘umpire’ laboratories determined the key elements: Au, Cu and Ag. The term ‘umpire’ here refers to the routine analysis of these laboratories using classical methodologies for precious and base metals. Twenty-three geoanalytical laboratories also participated in the analytical program for the following:

Au, Pt and Pd by fire assay

Cu, Al2O3, MgO, SiO2, Fe, S, CaO, TiO2, K and Mo by oxidising fusion with XRF

Total Sulphur by infrared combustion furnace

Hg by low level, aqua regia digestion

Fluorine by ion selective electrode

Chlorine by various methods

Ag, As, Bi, Cd, Co, Cr, Ni, Pb, Re, Sb, Se, Te, Th, U and Zn by 4-acid digestion

Gold by instrumental neutron activation analysis (INAA) on 20 x 85mg subsamples to confirm homogeneity (undertaken by ANSTO, Lucas Heights)