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| | Mining and the Environment |
 | | Eissler, M. The Metallurgy of Silver, A Practical Treatise on the Amalgamation, Roasting, and Lixiviation of Silver Ores: Including the Assaying, Melting, and Refining of Silver Bullion (London: Crosby Lockwood and Son, 1889). |
 | | The Geological Survey was established by the act of March 31, 1879 (20 Stat. |
 | | A History of the Precious Metals: From the Earliest Times to the Present, revised (New York: Cambridge Encyclopedia Company, 1902). |
| www.heritageresearch.com /mineadd.htm (148 words) |
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