Epithermal Gold and Silver Deposits
April 2017 by Chris RalphEpithermal deposits form in the ground at shallow depths. They are popular with prospectors because can yield very rich deposits and they are widespread in the Western US.
The faulting, folding and shearing that occurred in the Mother Lode belt has created zones of structurally weak rocks or contacts between different types of rock, which has been favorable for the deposition of gold bearing ores.
Only the richest ores could be worked and shipped off for processing at a profit. As a result, early mining in the southern part of the Humboldt Range was short-lived. In the 1880s, placers were discovered in Spring Valley and American Valley on the east side of the range...
There are a number of veins in the disseminated mineralization, but the principle ones on Round Mountain are known as the Los Gazabo and the Keane.
Common thought is the switchback slows the velocity of the rushing water and gold drops out from the cut bank to a fill gravel bar within or below the switchback. I am not going to disregard that model; however, I hope to improve upon it.
How rich does a hard rock ore have to be for it to be worthwhile to process and extract the gold?
If developed with metal detecting in mind, this virgin ground could be a bonanza for nugget hunting.
For the prospector, knowing what oxidized hydrothermal alteration looks like in the field is an important exploration tool.
The Bawl Mill • Legislative and Regulatory Update • Ask The Experts: Is an XRF gun useful for prospecting and mineral identification? • Ask The Experts: Is this deposit worth working? • Ask The Experts: Can a long range locator probe detect gold in quartz? • Weathering, Erosion and Placers • The PIGMI—a DIY Crevice Tool • Diary of a Diamond Prospector • The Ups and Downs of Nugget Hunting • Melman on Gold & Silver • Mining Stock Quotes and Mineral & Metal Prices