Tertiary low sulfidation (LS) epithermal deposits in the western USA often show evidence of the former presence of nanoparticle-sized precious-metal and silica phases in the highest grade (bonanza) ores. Here, nanoparticles are defined to have a size less than ~10 m. The ore-mineral textures that formed from aggregation of nanoparticles (or colloids) observed to date in these ores include elect...

The area underlain by the Barkerville Terrane has an important exploration and mining history dating from the discovery of placer gold on Keithley Creek in 1860. Placer gold production peaked in the 1860s, but continues at a modest scale to the present time. Lode gold production came mainly from the Wells mining camp, located near some of the richest placer streams in the district, between 1933...