Unusual Scorodite from the Cactus Gold Mines Middle Buttes Volcanic Complex, Kern County, California

摘要

The Middle Buttes Volcanic Complex is a topographic high consisting of Miocene (21.5 to 16.9 Ma) rhyolitic domes, breccias, and tuffs overlying Cretaceous-aged quartz monzonite basement, and surrounded by Quaternary alluvial sediments. The volcanic complex is located in southeastern Kern County, approximately 9 miles southwest of the town of Mojave, and approximately 60 miles north of Los Angeles, California. The complex was host to six epithermal, bulk-mineable precious-metal (gold and silver) deposits, which were mined by Cactus Gold Mines/CoCa Mines in the late 1980s and early 1990s. The deposits ranged in size between 125,000 tons with a grade of 0.185 oz/ton gold, to 5.5 million tons with a grade of 0.043 oz/ton gold. In addition, a bonanza vein system was mined intermittently between the 1930s and the 1960s. A total of approximately 440,000 ounces of gold and 5.3 million ounces of silver were extracted from the deposits at Middle Buttes (Blaske, et. al. 1991).