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The Big Hole has a surface of 17 hectares (42 acres) and is 463 metres (1,519 ft) wide. It was excavated to a depth of 240 metres (790 ft), but then partially infilled with debris reducing its depth to about 215 metres (705 ft). Since then it has accumulated about 40 metres (130 ft) of water, leaving 175 metres (574 ft) of the hole visible.
30 December 1982. Listed. 8 September 1983. List of Superfund sites. The Berkeley Pit is a former open pit copper mine in the western United States, located in Butte, Montana. It is one mile (1.6 km) long by one-half mile (800 m) wide, with an approximate maximum depth of 1,780 feet (540 m). It is filled to a depth of about 900 feet (270 m ...
Scale is one inch, ruled at one cm. The Rio Tinto Boron Mine (formerly the U.S. Borax Boron Mine) in Boron, California is California 's largest open-pit mine and the largest borax mine in the world, producing nearly half the world's borates. Ore reserves are sufficient for current economic production through early 2040's.
The Bingham Canyon Mine, more commonly known as Kennecott Copper Mine among locals, [3] is an open-pit mining operation extracting a large porphyry copper deposit southwest of Salt Lake City, Utah, in the Oquirrh Mountains. The mine is the largest human-made excavation, and deepest open-pit mine in the world, [4][5] which is considered to have ...
Moaning Cave from the bottom of the shaft. Moaning Caverns is a solutional cave located in the Calaveras County, California, near Vallecito, California in the heart of the state's Gold Country. It is developed in marble of the Calaveras Formation. It was discovered in modern times by gold miners in 1851, but it has long been known as an ...
Geography. The lake is over 20,000 acres (8,100 ha) when full. It is approximately 16 mi (25 km) long and 3.1 mi (5 km) wide. It has approximately 165 mi (265 km) miles of shoreline. Near the dam on the southeast side of the reservoir is an open bell-mouth spillway, 72 feet (22 m) in diameter, which is known as the Glory Hole. [3]
The Cerro Gordo Mines are a collection of abandoned mines located in Cerro Gordo in the Inyo Mountains, Inyo County, near Lone Pine, California. Mining operations spanned 1866 to 1957, producing high grade silver , lead , zinc ore, and more rarely gold ore and copper ore . [ 1 ]
Underground hard-rock mining. Underground hard-rock mining refers to various underground mining techniques used to excavate "hard" minerals, usually those containing metals, [1] such as ore containing gold, silver, iron, copper, zinc, nickel, tin, and lead. It also involves the same techniques used to excavate ores of gems, such as diamonds and ...