From silver in the Mexican Volcanic Belt to copper in the Arizona Porphyry Belt: Mining geophysics, site remediation, and nonrenewable resources

摘要

In the course of two weeks in late March, I walked to the top of two different moun- tains in two of the largest mining districts in North America. From a peak near Valenciana I looked along strike at the epithermal deposits of the fabulous silver vein and lode complex of the Beta Madre ("mother vein") in Guanajuato, Mexico. From Grassy Peak in the Galiuro Mountains I had a good view of the por- phyry copper deposit at San Manuel, Arizona. There was no mining activity in Guanajuato, and no smoke came from the smelter stack at San Manuel. It is likely that silver will con- tinue to come from the epithermal deposits in Mexico, includ- ing the state of Guanajuato, and copper will continue to come from Arizona. Economics and geophysics will both play a part in this.