OREAS 153a is one of three porphyry Cu-Au-Mo-S certified reference materials prepared from copper ore from the Waisoi district, Viti Levu, Fiji. The two deposits in the area are the Waisoi East deposit (quartz porphyry) and the Waisoi West deposit (diorite porphyry). Copper mineralisation in the region is accompanied by stockwork quartz veinlets and is characterised by bornite-chalcopyrite-pyrite assemblages. Twenty-one analytical laboratories participated in the program to certify the following elements:
|Analyte||Certified Value||1SD||95% Confidence Limits Low||95% Confidence Limits High||Method|
|Cu, Copper (wt.%)||0.712||0.025||0.701||0.723||4-Acid Digestion|
|Au, Gold (ppb)||311||12.0||306||315||Pb Fire Assay|
|Mo, Molybdenum (ppm)||177||9||173||181||4-Acid Digestion|
|S, Sulphur (wt.%)||1.27||0.070||1.23||1.30||4-Acid Digestion|
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