To: Ish who wrote (96631 ) 2/26/2005 4:55:56 PM From: cosmicforce Respond to Someone should have told the mining engineers in Colorado how to mine lead and gold. I'd prefer not to learn the same types of lessons from the farmers of corn.biology.usgs.gov The technology for extracting and purifying gold, silver, copper, lead, and other metals from sulfide ores was brought to the Western Hemisphere by Europeans. North American colonization and subsequent westward expansion in the United States were stimulated first by the search for precious metals and later by the needs of industry. As the United States grew westward, new ore deposits were discovered and exploited. Although extraction efficiency also improved, the nineteenth and twentieth centuries brought tremendous increases in scale to the mining industry through the advent of steam, internal combustion, and electric power. The basic methods for extracting metals, though, continued to rely largely on mechanical separation, gravity, water, and heat. Consequently, the increasingly large quantities of toxic metals and by-products released into the environment left their marks on U.S. biota. No information on the cumulative effects of metals mining and refining on biota exists, but 557,650 abandoned mines in the United States are estimated to have contaminated 728 square kilometers of lakes and reservoirs and 19,000 kilometers of streams and rivers (Mining Policy Center 1994). Areas where toxic releases to the environment from mining and smelting have caused large-scale effects on United States biological diversity or have jeopardized particularly rare or valuable living resources are numerous; some examples are listed in Table 2.
