Las Médulas—The Gem of the Roman Gold Mines
July 2018 by Alan J. Chenworth
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.
The most obvious benches are usually near the valley floor, but they can be thousands of feet above the valley floor. Since benches were made by streams, they can contain placer deposits.
Arizona is well-known for its copper-gold porphyries and massive base metal-gold sulfide deposits such that primary gold deposits in the state are often overshadowed.
Geology is a science of general tendencies with frequent exceptions, not one of hard and fast rules that are always true and never vary. For almost every well-accepted rule of gold deposits, I can point you to a number of important exceptions.
New theories have been developed and they may lead to new discoveries and give prospectors some new insight on where to look for diamonds.
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