History & Geology
Eastern Arizona: Gold and Base Metal Deposits—Part I
February 2011 by W. Dan Hausel
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.
Enrichment of Mineral Deposits by Weathering—Part I
The exact minerals formed in the concentrated supergene deposits depends much on the type of country rock around the deposit and the chemistry of the deposit itself, but if conditions are right, this process will form some rich patches of bonanza ore, in some places valued at thousands of dollars to the ton.Glaciers and Placer Gold Deposits
It also happens sometimes that glaciers will bury valuable placer deposits. This occurs when the glacier goes over the top of an existing placer deposit.
Testing Ores for Free Gold
I get a number of questions from people about testing and treating hard rock ores. The simplest way, but also an expensive one, is to just have an assay test done by an independent assay firm. As an alternative...
The Birimian Greenstone Belts of West Africa
The country we were to visit was Burkina Faso, a small country about the same size of my home state of Nevada with about 10 times more people. The second day I was in Africa, we went out to the goldfields for the first time.
The Ely Copper-Gold District of Nevada
The main ore deposits of the Ely district are associated with an east-west belt of altered and mineralized rocks measuring about one mile wide that extends 8 miles westward from Ely.
Alaska Gold: Lisianski Inlet's First Bonanza
In 1967, a local resident showed me a pouch of small gold nuggets and flakes. Several years later I asked the same person where that gold was found. He responded, “From the streambed below the old stamp mill at Apex.”
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.
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