Gold occurrence of the Yangshan gold ore field and gold minerals' characteristics,Gansu Province

The Yangshan gold deposit is a para-carlin type gold deposit with the major gold mineralized in four altered types which include altered phyllite,altered plagioclase granite porphyry,altered sandstone and altered limestone.The gold often occurred as independent gold mineral,while a few gold occurred in dispersing state.Native gold is the main gold mineral in ores,and electrum is the second gold mineral.Gold minerals,in patterns of inclusion gold,fissure gold,intergranular gold etc.,layed and distributed in major Au-loading minerals including arsenopyrite,pyrite,stibnite and clay mineral etc.,of which arsenopyrite,pyrite,stibnite have advantages for loading gold.Gold minerals occurred in diversity shapes with the major granularity being micro fine.The characteristics of gold minerals showed that the ore-forming matters of the gold deposit in this area is mainly from metamorphic rocks,magmatic rocks and mantle,and the mineralization is related to the intermediate-acid intrusive rocks of the Late Indo-Chinese Epoch,which is accordance with the genesis knowledge obtained from geological and geochemical research.