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Mineralized Calderas in Colorado
May 2002 by Edgar B. Heylmun, PhD
A caldera is a large circular volcanic depression caused by collapse due to the removal of molten magma from an underlying magma chamber. The removal of magma is due to explosive venting of lava and pyroclastic material.
Mining Sisters Make History
Judy Etherton wasn’t out to make headlines or break any barriers when she entered the mining industry more than 30 years ago.
Detecting the Fringe Areas
One prime example is an area that I have talked about in many of my articles. This is a very large area and I will actually describe its location again.
The Seven Troughs Mining District
The favorable geology of the northeastern and central parts of the Seven Troughs Range are the parts most interesting to prospectors. They are underlain by a thick sequence of Tertiary volcanic rocks, mostly rhyolites and andesites.
The Smell of Gold -- Part II
While mapping, I also found rock chips in the soil that were characteristic of the same wall rock alteration that occurs adjacent to the known lodes in the greenstone belt.
Company Notes
• U.S. Gold Corporation
• AZCO Mining Co.
• Canyon Resources Corporation
• Placer Dome, Inc.
• Vista Gold Corp.
• Grupo Mexico
Care and Lubrication of a Model 13 Laboratory Wilfley Table
A Wilfley table works best when all of the mineral being run across it (the pulp) is about the same size. For this reason, I took a good look at each of the samples.
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