Geology and Temporal Evolution of Alteration and Au-Sb-W Mineralization, Subnite Mining District, Idaho

Résumé du livre

"The Stibnite district, which is part of the larger Yellow Pine mining district, produced nearly a million ounces of gold (Au) plus substantial tungsten (W) and antimony (Sb) since 1900. The district hosts the United States' largest resource of Sb, a critical mineral resource, and a large Au reserve (over 140 metric tons of Au). Early geologic studies noted the essential characteristics of the complex ores, but the age and origin of the mineralization at Stibnite have been controversial for nearly a century. This Idaho Geological Survey (IGS) study, supported by Midas Gold, Inc., was designed to clarify the geologic setting and age of hydrothermal alteration and mineralization by applying modern geochronological and analytical techniques on carefully characterized samples from drill core as well as surface exposures. As described in the subsequent chapters, our observations of mineral associations coupled with detailed age determinations, isotopic studies, and microprobe analyses of Au-bearing pyrites have documented at least two, and possibly three, overprinted major hydrothermal events at Stibnite. The results show that hydrothermal activity and ore deposition at Stibnite took place in pulses within a 20-million-year interval from early-Tertiary to mid-Tertiary time, largely focused along major structures"--Page 2