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翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Comstock Lode ： ウィキペディア英語版 Comstock Lode The Comstock Lode is a lode of silver ore located under the eastern slope of Mount Davidson, a peak in the Virginia Range in Nevada (then western Utah Territory). It was the first major discovery of silver ore in the United States. After the discovery was made public in 1859, it sparked a silver rush of prospectors to the area, scrambling to stake their claims. The discovery caused considerable excitement in California and throughout the United States, the greatest since the California Gold Rush in 1849. Mining camps soon thrived in the vicinity, which became bustling commercial centers, including Virginia City and Gold Hill. The Comstock Lode is notable not just for the immense fortunes it generated and the large role those fortunes had in the growth of Nevada and San Francisco, but also for the advances in mining technology that it spurred, such as square set timbering and the Washoe process for extracting silver from ore. The mines declined after 1874, although underground mining continued sporadically into the 1920s. ==Geology== Volcanic vents to the east covered the area during the Tertiary, and a fault fissure opened the east slope of the Virginia Range. The east slope of the range forms the footwall of the Lode, and is composed of diorite, while the hanging wall is composed of andesite, which the miners called "porphyry". The fault fissures filled these fissures with "mineral-bearing quartz". The miners stated "porphyry makes ore". "The ore bodies were thinly scattered through the wide Lode 'like plums in a charity pudding', and nearly all of them were found in the wide upper section and along or near the east wall". Although the miners extended their work in all directions, only "sixteen large and rich ore bodies" were found, most less than 600 feet in depth.〔 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「Comstock Lode」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.