Visible gold in arsenian pyrite at the Shuiyindong Carlin-type gold deposit, Guizhou, China: Implications for the environment and processes of ore formation
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- 作者：Wenchao Su ; Bin Xia ; Hongtao Zhang ; Xingchun Zhang ; Ruizhong Hu
- 关键词：Native gold ; Arsenian pyrite ; Ore-fluid evolution ; Carlin-type deposit ; Guizhou
- 刊名：Ore Geology Reviews
- 出版年：2008
- 出版时间：June 2008
- 年：2008
- 卷：33
- 期：3-4
- 页码：667-679
- 全文大小：2163 K
文摘
Carlin-type gold deposits are best known for the scarcity of visible gold in their ores. It has long been recognized that the majority of gold is “invisible”, such that it cannot be resolved by conventional microscopy, and resides in arsenian pyrite. Shuiyindong differs in that sub-μm to μm-sized native gold is present in arsenian pyrite veinlets and disseminations. It is also the largest (55 tonnes) and highest grade (7 to 18 ppm), stratabound, Carlin-type gold deposit in Guizhou, China and has produced 5 tonnes of gold from sulfide refractory ores extracted by underground mining methods. In this study, an electron microprobe analyzer (EMPA) was used to map the spatial distribution of “invisible” gold and sub-μm to μm-size visible gold particles in arsenian pyrite in high-grade ore samples from the Shuiyindong. The samples studied are hosted in Permian bioclastic ferroan limestone of the Longtan Formation and exhibit evidence of decarbonation, silicification and sulfidation. Arsenian pyrite with detectable Au (> 400 to 3800 ppm) is disseminated in altered limestone and was deposited in two stages separated by an episode of corrosion in a veinlet.