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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.
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Hunches, Choices and Guesses
September 2013
When you approach a location, even if you've been there before, you should consider all the factors and conditions present at the site. This includes both natural and man-made factors.
When you approach a location, even if you've been there before, you should consider all the factors and conditions present at the site. This includes both natural and man-made factors.
Melman on Gold & Silver
November 2007
World stock markets recovered from the brink of catastrophe to post sterling performances, based in large part on a one-half percent reduction in the Fed Funds rate enacted by the Federal Reserve Board.
World stock markets recovered from the brink of catastrophe to post sterling performances, based in large part on a one-half percent reduction in the Fed Funds rate enacted by the Federal Reserve Board.
California Suction Dredging Update
July 2012
Another California Assembly member, Jared Huffman, is attempting to ban dredging in the state on a more permanent basis.
Another California Assembly member, Jared Huffman, is attempting to ban dredging in the state on a more permanent basis.
Sulfides, Selenides and Tellurides
June 2007
The early day miners feared it, and it happened a lot more often than they would have liked: the easily worked rich surface ores they discovered gave way as they mined downward to a vein full of sulfides, base metals and other nasty, rebellious and...
The early day miners feared it, and it happened a lot more often than they would have liked: the easily worked rich surface ores they discovered gave way as they mined downward to a vein full of sulfides, base metals and other nasty, rebellious and...
Administration Officials Pledge to Work Closely With Miners
January 2002
The nation’s mining industry can expect a more favorable working climate, Bush administration officials told a receptive audience at the Northwest Mining Association’s (NWMA) annual convention.
The nation’s mining industry can expect a more favorable working climate, Bush administration officials told a receptive audience at the Northwest Mining Association’s (NWMA) annual convention.
Silver Bonanza in the Sierra Madre; The Glorious Past of Batopilas—Part III
December 2007
In 1880, Alexander Roby Shepherd, former governor of Washington, DC, prepared to move his wife and family of six children to the wilds of the Sierra Madre. Going with him would be mining men, cooks, assistants, a bookkeeper and others to assist in the new adventure.
In 1880, Alexander Roby Shepherd, former governor of Washington, DC, prepared to move his wife and family of six children to the wilds of the Sierra Madre. Going with him would be mining men, cooks, assistants, a bookkeeper and others to assist in the new adventure.
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