History & Geology
Epithermal Gold and Silver Deposits
April 2017 by Chris Ralph
Epithermal 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 Golden Streams of Butte County, California
Even though these were some of the earliest placer deposits to be worked, there is still plenty of gold left today—it just takes more work to recover. Knowing about the old locations where gold has been found is the first step to success.
Enrichment of Mineral Deposits by Weathering—Part II
While both zinc and lead deposits also are enriched by the surface weathering process, in part two we will look at the enrichment process for copper and also gold deposits, and at the interpretation of leached outcrops to figure how rich the concentrated deposits below them may be.
The Rochester Mining District of Nevada
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...
The Giant King Mine
Most gold-bearing veins in this region are controlled by fractures associated with the Melones Fault, a late Cretaceous structure that is 108 to 127 million years old.
Can You Recognize Valuable Ores?
The process of recognizing ores all starts with being able to recognize some basic minerals and knowing what hard rock ore looks like in the districts where you prospect.
The Rush to Treasure Hill
There were some exceptional times in the far-flung history of the West. Rich finds of minerals that set men’s souls ablaze. From the rich gold fields of California, men who arrived too late to find riches went searching in every direction. The trail that we will follow leads east, past the shining silver district of the Comstock Lode.
Greenstone and Gold
Contacts, faults and zones of weak rock are all places that can act as a pipeline to convey gold-bearing fluids, leading to valuable deposits.
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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
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