Geological Characteristics and Occurrence Characteristics of the Chaganchulu Gold Deposit in Inner Mongolia

Ore bodies of the Chaganchulu gold deposit,a tectonic-altered rock type,occur in hypabyssal-superficial volcano instrusive-rock( sub-volcano quartz trachyandesite) in the Amushan Formation. Analyses of petrology,petrography and geochemistry of the sub-volcano quartz trachyandesite have revealed a calcium-poor type and aluminum- oversaturated series,a major host rock for the gold deposit,and secondly host-rock fine-grained diorite-porphyrite. The useful component is mainly Au,followed by Ag. The main mineral components are of natural gold,pyrite and limonite. The coarse and huge grains occur in gold,which are flake-shaped,or bending,irregular,and the thickness of which is less than 0. 010 mm. The natural gold,an intercrystalline one,is closely related to the quartz vein in the sub-volcano quartz trachyandesite.