OREAS 505b

OREAS 505b was prepared from a blend of porphyry copper-gold ores, barren granodiorite and a minor quantity of Mo concentrate. The ores were sourced from both the Northparkes Mine and Ridgeway Mine. Both mines are located in the Central West of New South Wales, Australia. The barren granodiorite was sourced from the mafic, S-Type, Late Devonian Bulla Granodiorite complex located in northern Melbourne, Australia.

Twenty seven commercial analytical laboratories participated in the program to certify the elements reported in Table 1. The following methods were employed:

• Gold via 15-50g fire assay with AAS finish (14 laboratories) and ICP-OES (12 laboratories) finish;
• Gold via 15-50g aqua regia digestion with ICP-MS finish (11 laboratories), AAS (4 laboratories) and ICP-OES (1 laboratory) finish;
• Aqua regia digestion for full elemental suite ICP-OES/MS and AAS finish (up to 26 laboratories depending on the element);
• 4-Acid digestion for full elemental suite ICP-OES/MS finish (up to 25 laboratories depending on the element);
• Gold by instrumental neutron activation analysis (INAA) on 20 x 85mg subsamples to confirm homogeneity (1 laboratory only: ANSTO, Lucas Heights, Australia);
• Major and trace elements determined by borate fusion XRF (Al2O3 to TiO2), laser ablation with ICP-MS (Ag to Zr), LOI at 1000°C and C+S by infrared combustion furnace (1 laboratory only: Bureau Veritas Geoanalytical, Perth, Australia).