The mineralogy of the copper - Gold ore deposits at the Phu Kham, Mine, Laos

The Phu Kham "Mountain of Gold" copper - gold deposit is located in the Xaisomboun District in Vientiane Province in Lao PDR, approximately 100 km northeast of the capital city of Vientiane. The mine is a major Cu-Au deposit which is located within the junction zone between the Loei and Truongson Fold Belts. These belts respectively from the west and northeast margins of the Khorat - Kontum region or basin, which comprises deformed Palaeozoic volcano - sedimentary sequences and associated with acid to intermediate intrusive rock, intermediate volcanic-clastics, interbedded Permo-Carboniferous limestones, red beds and schist. Mineralization at the Phukham mainly occurs within diorite bodies, intermediate porphyry dykes, schist as well as a skarn bordering limestone. Most of the ore bearing minerals comprise within the PhuKham deposit comprises predominantly pyrite, chalcopyrite, bornite, arsenopyrite and sphalerite which occupy fractures within pyrite grains and quartz-carbonate veins. The mineralized veins often show irregular pods of white buck quartz with interstitial patches of carbonate, chlorite and minor coarse chalcopyrite. These veins do not appear to be folded or boudinaged and occur throughout the deposit. They extend into the red beds, but chlorite infill becomes more abundant and copper minerals become much less common.