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 Goldfield Mining District -- Then and Now
In 1983, some of the ore yielded more than 2,500 ounces of gold within 30 feet of the surface. The shoot pinched to a narrow vein.
The Pearce Mineralized Area, Dragoon Mountains, Arizona
...I would bet considerably more lode gold and silver remains to be found in this area, and there are possibilities for small placers and nugget shooting.
Gangue Minerals - What Do They Tell Us?
There are a large number of different kinds of gangue minerals, and each of them has its own tale to contribute to the story of the chemistry and geology of a deposit.
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Electrum: Gold and Silver Together
...if you are out prospecting and find something that looks very much like a nugget but has an odd greenish-gray cast to it, don’t be too quick to simply toss it aside as junk.
Las Médulas—The Gem of the Roman Gold Mines
This mine was a real wonder of engineering, and the water supply and drifts had to be carefully managed to keep it in operation. In fact, it didn’t close due to lack of gold, but instead closed with the fall of the Roman Empire.
Alluvial Paystreaks
The gravels in contact with the bedrock or false bedrock base are often the richest. The same facts apply to the alluvial paystreaks that are formed on gravel bars; the lowest level of the gold-bearing gravel is normally the richest.
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The Bawl Mill
• Legislative and Regulatory Update
• Ask The Experts: Is an XRF gun useful for prospecting and mineral identification?
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• 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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