白云鄂博超大型矿床中金的分布和赋存状态研究

近来，在著名超大型白云鄂博稀土铌铁矿床中发现了自然金，许多矿石的Au含量高出克拉克值2－30倍。尾砂样品Au含量与中国砂金矿床品位接近。本项目拟研究该矿床不同类型矿石和围岩中Au的含量和赋存状态、自然金的矿物组合、成矿阶段、物质来源和成因。.

Native gold has been discovered in Bayan Obo giant deposit in 2000 and.reported in 2002. Large samples (>100kg) of dolomite type ore and specimen of fault breccia from the main fault (F1) from the east mine and tails in the Bayan Obo have been collected. Native gold has been found, again, from tails, that repeated the previous discovery. The chemical constituent of native gold was analyzed by electron microprobe with EDS. A high Th grain is closely associate with one gold grain that strongly proves that the gold grain is from the Bayan Obo deposit which is intensively rich in Th. Chemical analysis indicates that.quartz bearing dolomite type ore is enriched in Au at about 40×10-9g/g, and Au in tails is also enriched to the same extent. We conclude that the native gold really occur in Bayan Obo, but Au concentration at the present level is very low. The very small amount of native gold carries no economic significance and it is very difficult to do research work on it.