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Gold mining in the United States has taken place continually since the discovery of gold at the Reed farm in North Carolina in 1799. The first documented occurrence of gold was in Virginia in 1782.〔A.H. Koschmann and Bergendahl, 1968, ''Principal Gold-Producing Districts of the United States'', US Geological Survey, Professional Paper 610, p.253.〕 Some minor gold production took place in North Carolina as early as 1793, but created no excitement. The discovery on the Reed farm in 1799 which was identified as gold in 1802 and subsequently mined marked the first commercial production.〔A.H. Koschmann and Bergendahl, 1968, ''Principal Gold-Producing Districts of the United States'', US Geological Survey, Professional Paper 610, p.211.〕 The large scale production of gold started with the California Gold Rush in 1848. The closure of gold mines during World War II by the War Production Board Limitation Order No. 208 in autumn 1942 was a major impact on the production until the end of the war. US gold production greatly increased during the 1980s, due to high gold prices and the use of heap leaching to recover gold from disseminated low-grade deposits in Nevada and other states. In 2012 the United States produced 230 tonnes of gold, making it the third-largest gold-producing nation, behind China and Australia.〔(US Geological Survey, Mineral Commodities Summary (2013): ''Gold'' ) PDF file, retrieved 29 January 2013.〕 Most gold produced today in the US comes from large open-pit heap leach mines in the state of Nevada. The US is a net exporter of gold.〔Mining review, Mining Engineering, May 2007, p.28.〕 ==Gold mining by state== ===Alabama=== Gold was discovered in Alabama about 1830, shortly following the Georgia Gold Rush. The principal districts were the Arbacoochee district in Cleburne County, mostly from placer deposits, and the Hog Mountain district in Tallapoosa County, which produced 24 thousand troy ounces (750 kg) from veins in schist.〔A.H. Koschman and M.H. Bergendahl (1968) ''Principal Gold-Producing Districts of the United States'', U.S. Geological Survey, Professional Paper 610, p.6-8.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Gold mining in the United States」の詳細全文を読む スポンサード リンク
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