Huge deposits of American iron ores were discovered as early as the 19th century – 1844. In 1854 their industrial development began, and the reserves have not yet dried up. The area is also distinguished by the quality of the raw materials. The iron content in the ore reaches 60%. Magnetite quartzites (25-35%Fe) and hematite (40-60%Fe) prevail.Now the largest amount of high quality iron ore is mined in the area of Mesabi. It provides 80% of the iron ore annually, of all the production of the largest basin in the United States.
Iron ore mining in the U.S. is done open and closed, because the depth of its occurrence varies. It varies from 10 to 500 meters. The largest iron ore deposit in the world, the Hull-Rust-Mahoning Open Pit Iron Mine, is also located in this area. Up to 8.5 million tons of pure raw materials are mined here annually. It is even on the register of National Historic Landmarks and has been in operation since 1893.
Uranium Ores
The Colorado Plateau is one of the largest deposits of uranium-vanadium ores. These metals are now very important to the steel industry, which has increased the intensity of metal mining in the United States. There are more than 2,000 deposits, some of which were discovered as early as 1898. The largest and most important for industrial production of ferrous metals are considered:
- Mount Taylor;
- Ambrosia Lake;
- Monument Valley;
- Jurvan;
- North Alicka;
- Mi Vida;
- White Canyon.
Ore reserves in the U.S. in the Colorado Plateau are estimated at 70 thousand tons, according to geological exploration, its potential is much higher. The amount of projected resources is estimated at 1 million tons. The ore here is represented by the minerals carnotite and tyamunite, containing up to 5% uranium.
Deposits on the Colorado Plateau provide 88% of the uranium ores from U.S. production. It can be considered unique because of the purity and quality of the raw material.
Copper
The United States produces 12.7% of the world’s copper resources. The largest amount of this raw material is produced in the state of Arizona. The main copper producing areas are considered to be Jerome, Aho, Bisbee, Globe-Miami, and White Mesa. A huge role in the U.S. non-ferrous metallurgy is played by the Morenci deposit, whose reserves are estimated at 832 million tons.
The most famous in the world is the Bingham Canyon deposit, with a resource potential of 637 million tons. But after a massive landslide in 2013, it halted operations due to huge destruction and environmental problems. It is also noteworthy that here, during the processing of raw materials, palladium was released (150 – 200 kg per year). This is a very rare metal, which is highly valued in the metals industry.
Gold compounds are also mined at copper deposits in America. They are formed by enriching the ore in the mills, but have industrial value. The bulk of the copper is mined at 17 mines in 5 states. They provide 99% of the country’s copper production. The U.S. is the 5th largest producer of this base metal in the world.
Gold
Although gold is also produced in copper mines, there are individual precious metal deposits in the country. The United States is one of the three leading nations in its production. The first deposits were discovered back in 1779 in Alaska. The largest deposits are in Nevada. The areas of industrial value are:
- Carlin;
- The gray-brown mine;
- Gold Mine;
- Gold Fleece Mine;
- Robinson.
Tourists also mine legally in the country. There are small loose gold deposits in California and Alaska that have no industrial value. But they attract miners who try to get rich or have fun with their valuable finds. There used to be even gold rush phenomena in the area.
The Precious Stones
Most emeralds have been found in North Carolina. Sapphires are mined in the state of Montana. Large quantities of beryls, topaz, moonstone, and aquamarines have also been found. In Arizona, gems have been mined for over 1000 years. The very first was turquoise, a blue-green stone. It became the world center for the production of this high quality mineral. It also received state significance in 1974. There are also large quantities of amethysts found in Arizona, in the Four Peaks mine.
Arizona has a rare type of gemstone called ant garnets. They are dark red, small-sized stones mined by ants. They haul them into the anthills along with building materials.
The state of Oregon is famous for Oregon sun stones. These are a rare type of clear opal that is bright yellow in color. Deposits in the United States of America for these stones are considered unique and are listed as natural treasures. It is formed due to the high content of copper in quartzite. Because of this, when exposed to direct sunlight, it reflects flashes of light, making the stone unique. California’s mineral potential is somewhat lower. Tourmalines and ornamental stones (jasper, benitoite, opal) are mined here the most.
Utah has distinguished itself by being the only place in the world where the Tiffany’s stone, or “purple passion,” can be found. It has a variegated pink and purple coloring, is easy to work with, and is excellent for creating jewelry. The most important stone in Arkansas is known as “rock crystal” or quartzite. Its purity attracts attention, which is why quartzite from U.S. deposits is in demand all over the world. Nevada is known for obsidian, a black volcanic glass.
Hydrocarbon minerals
Extraction of oil resources on the territory of the country began as far back as 300 years ago. Most of the hydrocarbon deposits are located in Texas, Alaska and California. Light and shale oil are widespread in America. The oldest fields in the U.S. are Midway Set (1894), East Texas (1930) and the Bakken Formation (1953). The first is located in the state of California and its reserves are estimated at 410 million tons of oil. Each year the Midway Set provides the country with 72 million tons of high quality hydrocarbons.
The Bakken formation is one of the largest sources of fuels in the United States. It is a source of light oil – containing minimal impurities. It uses directional drilling and hydraulic fracturing, which, unlike horizontal drilling, brings large-scale production. The East Texas field is one of the largest, and the leader in terms of annual hydrocarbon production.
The fields in Alaska lead in the number of geological oil reserves. Pradahoe Bay, which was discovered in 1963, is considered the main one. Its potential is estimated at 3.1 billion tons of oil and 730 billion cubic meters of gas. Oil here has a low density (0.844), which reduces processing costs and increases the cost of raw materials.
Oil production in the U.S. is carried out not only on land but also on the sea shelves. One of the most remarkable is the Petronius platform, which provides a daily production of 3 thousand cubic meters of oil and 2 million cubic meters of gas. It is located in the Gulf of Mexico near New Orleans.
Coal
Solid fuel minerals are also plentiful in the United States. The largest basin of hard coal, the Appalachian Basin, is located here. More than 15 million tons of coal are produced annually in 300 coal fields. Coal is mined by both open-pit and closed-pit methods. The type of production depends on the depth of the raw material. The advantage of this coal basin is the shallow bedding of the rock, which greatly reduces the cost of mining.
Hard coal and anthracite are also mined in Illinois, in the basin of the same name. The reserves of raw materials are estimated at 365 billion tons, but only 35 are commercial. The deposits of this basin are developed only by open-pit and cut-and-fill method, because the depth of occurrence of the rock does not exceed 300 meters. It brings the country 150 – 160 million tons of hard coal per year.
Lignite is mined in the western and southern United States:
- Montana,
- Wyoming,
- Illinois,
- Kentucky,
- West Virginia,
- Utah, Arizona,
- Louisiana.
Reserves of this natural resource in the country are estimated at 128 billion tons. New deposits in Alaska are now being explored, but their size is far inferior to the already discovered largest basins in America. Despite this, geologists predict a major find in the near future.