Abstract:

Pyrite is the main auriferous mineral in hydrothermal gold deposits. The auriferous properties of pyrite have been researched in many single deposits and some related experiences were accumulated. But it’s rare of the synthetic and quantitative studies and an universal understanding about properties of auriferous pyrite is paid much attention. In this paper, based on mineralogy and chemical compositions of pyrite in various types (including Carlin, orogenic, magmatic-hydrothermal and epithermal gold deposits) of hydrothermal gold deposits in China, the quantitative and comprehensive studies about auriferous properties of different grain sized, various crystalline form and varied As contents pyrite have been conducted. It’s suggested that the auriferous properties of pyrite are mostly negative correlated with its grain size (the correlation coefficients range from -0.049 to -0.783) and idiomorphic degree (correlation coefficients range from -0.049 to -0.989), positive correlated with its As contents (correlation coefficients range from 0.189 to 0.998).The auriferous properties of fine grain, allotriomorphic crystal form and high As contents pyrite are mainly better than that of coarse grain, idiomorphic crystal form and low As contents pyrite. Compared with the coarse and idiomorphic crystal form pyrite, the fine grain and allotriomorphic crystal form pyrite can easily wrap up gold in its lattice defects formed in non-ideal growth conditions. The high As contents pyrite mainly formed through As isomorphism substituting S in pyrite and can easily produce lattice defects, in which the gold hosted, because of the different chemical property of As and S. These may be some reasons for the auriferous properties of pyrite above. The invisible gold in the pyrite may convert into visible one by dissolving, migration and re-precipitation in hydrothermal systems.

Key words: crystal characteristics, As content, auriferous pyrite, hydrothermal gold deposit, China