Mineral County is a county located in the U.S. state of Montana. As of the 2010 United States Census, the population was 4,223. Its county seat is Superior.
Granite County is a county located in the U.S. state of Montana. As of the 2010 United States Census, the population was 3,079. Its county seat is Philipsburg. The county was founded in 1893, and was named for a mountain which contains the Granite Mountain silver mine.
Superior is a town in, and the county seat of, Mineral County, Montana, United States. The population was 812 at the 2010 census.
The Green River Formation is an Eocene geologic formation that records the sedimentation in a group of intermountain lakes in three basins along the present-day Green River in Colorado, Wyoming, and Utah. The sediments are deposited in very fine layers, a dark layer during the growing season and a light-hue inorganic layer in the dry season. Each pair of layers is called a varve and represents one year. The sediments of the Green River Formation present a continuous record of six million years. The mean thickness of a varve here is 0.18 mm, with a minimum thickness of 0.014 mm and maximum of 9.8 mm.
Hebgen Lake is a reservoir created by the Hebgen Dam, located in Gallatin County in southwest Montana. It is well known for the 1959 Hebgen Lake earthquake which occurred nearby on August 17, 1959, forming Quake Lake, which is located immediately downstream.
The Midcontinent Rift System (MRS) or Keweenawan Rift is a 2,000 km (1,200 mi) long geological rift in the center of the North American continent and south-central part of the North American plate. It formed when the continent's core, the North American craton, began to split apart during the Mesoproterozoic era of the Precambrian, about 1.1 billion years ago. The rift failed, leaving behind thick layers of igneous rock that are exposed in its northern reaches, but buried beneath later sedimentary formations along most of its western and eastern arms. Those arms meet at Lake Superior, which is contained within the rift valley. The lake's north shore in Ontario and Minnesota defines the northern arc of the rift. From the lake, the rift's eastern arm trends south to central lower Michigan, and possibly into Indiana, Ohio, Kentucky, Tennessee, and Alabama. The western arm runs from Lake Superior southwest through portions of Wisconsin, Minnesota, Iowa, and Nebraska to northeastern Kansas, and possibly into Oklahoma.
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. 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.
Silver mining in the United States began on a major scale with the discovery of the Comstock Lode in Nevada in 1858. The industry suffered greatly from the demonetization of silver in 1873 by the Coinage Act of 1873, known pejoratively as the "Crime of 73", but silver mining continues today.
Manganese is a ghost town and former mining community in the U.S. state of Minnesota that was inhabited between 1912 and 1960. It was built in Crow Wing County on the Cuyuna Iron Range in sections 23 and 28 of Wolford Township, about 2 miles (3.2 km) north of Trommald, Minnesota. After its formal dissolution, Manganese was absorbed by Wolford Township; the former town site is located between Coles Lake and Flynn Lake. First appearing in the U.S. Census of 1920 with an already dwindling population of 183, the village was abandoned by 1960.
The Elk Point Group is a stratigraphic unit of Early to Middle Devonian age in the Western Canada and Williston sedimentary basins. It underlies large area that extends from southern boundary of the Northwest Territories in Canada to North Dakota in the United States. It has been subdivided into numerous formations, many which host major petroleum and natural gas reservoirs.
Jacobsville Sandstone is a red sandstone formation, marked with light-colored streaks and spots, primarily found in northern Upper Michigan, portions of Ontario, and under much of Lake Superior. Desired for its durability and aesthetics, the sandstone was used as an architectural building stone both locally and around the United States. The stone was extracted by thirty-two quarries throughout the Upper Peninsula approximately between 1870 and 1915.
The Bayfield group is a quartz sandstone found in Wisconsin along the Lake Superior coast. It is named for the village of Bayfield, Wisconsin, but was once known as Western Lake Superior Sandstone.
Petroleum County is a county in the U.S. state of Montana. As of the 2010 United States Census, the population was 494, making it the least populous county in Montana and the seventh-least populous in the United States. Its county seat is Winnett. The county's area was partitioned from Fergus County to become the last of Montana's 56 counties to be organized.
Iron mining in the United States produced 42.5 million metric tons of iron ore in 2015, worth US$3.8 billion. Iron ore was the third-highest-value metal mined in the United States, after gold and copper. Iron ore was mined from nine active mines and three reclamation operations in Michigan, Minnesota, and Utah. Most of the iron ore was mined in northern Minnesota's Mesabi Range. Net exports were 3.9 million tons. US iron ore made up 2.5 percent of the total mined worldwide in 2015. Employment as of 2014 was 5,750 in iron mines and iron ore treatment plants.
In 2015, 27.6 million metric tons of marketable phosphate rock, or phosphorite, was mined in the United States, making the US the world's third-largest producer, after China and Morocco. The phosphate mining industry employed 2,200 people. The value of phosphate rock mined was US$2.2 billion.
