History & Geology
Picks & Pans: Gold Recovery in Placer Mining Operations
August 1999 by Staff
Two of the major factors affecting the profitability of a placer mining enterprise are the relative efficiency of the mining equipment, and the rate and percentage of recovery obtained while conducting mining operations.
Green Valley Gold District, Payson, Arizona
Most gold-bearing quartz veins found in the district were fracture fillings in faults enclosed by crushed quartz zones along their margins. Since the host rocks were often extensively weathered, portions of the veins stood out as positive, resistant outcrops. The gold-bearing veins ranged from a few inches wide to the vein at the Gowan mine that was as much as 12 feet wide. Potholes and Other Bedrock Traps
Potholes in bedrock can trap placer minerals and even be glory holes. They are, at least, interesting geologic phenomena, and at best, a treasure trove of gold nuggets.
Gold in Tertiary Gravels
In some places, semi-continuous sections of riverbed can easily be linked in many places to identify the path of the ancient rivers.
Gold From Cemented Gravels
The truth is that cemented gravels are really not all that complex. There is no mystery of how gold grew there or somehow wormed its way into these solid gravels.
Northwestern Alaska Mineral Resources
Gold and jade are actually only minor mineral resources for the Northwestern Alaska region as a whole. Modern prospecting has focused more on base metal than precious metal resources.
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.
Jadeite in California
...two jadeite locations in California have been thoroughly researched by geologists. There are no doubt others that lie in wait.
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