History & Geology
Gold Deposition and Gradients of Placer Streams—Part I
June 2012 by Jim Halloran
When placer miners from the gold rush era began experimenting with the slope of their sluices, they must have pondered the ideal slope for trapping gold in a creek bed too. Logic suggests the same is true for streams...
Mining Pegmatite Deposits
With successively lower temperatures as the water mixture cools, new sets of minerals are formed and many of those stable at a higher degree of heat became subject to alteration as the temperature progressively moved lower.
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.
PGMs in the United States
Until just recently, platinum-group metals (PGMs), especially palladium, had been holding their own on the market. But, Russia has now resumed shipments and it has brought prices down.
California: The Land of Big Nuggets—Part II
There are a number of Tertiary river channels in the area, most of which trend south-southwest. They tend to be steep, narrow, and rich with coarse gold.
All About Pyrite
Most prospectors learn early that pyrite is fool's gold...but the truth is it can be an excellent indicator mineral for gold and in many cases does contain small amounts of gold.
All About Garnets
I get a lot of questions from prospectors about garnets, their value and what they tell us about the geology of some types of mineral deposits. So I thought it would be a good idea to take a closer look at the lowly garnet and learn a bit more about it.
Round Mountain, Nevada
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.
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