Crushed ore of differing grade and recovery from the Bananghilig gold deposit, Tambis project area, NE Mindanao, Philippines, has been the subject of gold deportment studies. The coarser grained components of the crushed ore, subject to bottle-roll cyanide leaching recovery testing, have been subjected to heavy mineral and composite grain separations. The heavy mineral and composite grain separates, the latter including composites of sulphides, sulphosalts, precious metal alloys, quartz, carbonate and clay, have been prepared as polished mounts and thin sections. The polished mounts and thin sections were systematically optical microscopically scanned with some selective follow-up Electron Microprobe analysis. The studies determined that variable and in some cases difficult gold metallurgy of the ore material relates to:
a). The grain-size of microscopic to sub-microscopic free gold-silver alloy inclusions in quartz, pyrite, base metal sulphides, sulphosalts and carbonate
b). Gold occurring as solid solution in pyrite, arsentiferous pyrite and arsenopyrite in close spatial association with arsenic substitution for sulphur in the respective ironsulphide host mineralogy.
c). The occurrence of gold-silver telluride and gold bearing silver telluride minerals.