Oreis a deposit in Earth’scrustof one or more valuableminerals. The most valuable ore deposits containmetalscrucialtoindustryandtrade, likecopper,gold, andiron.
Copper ore is mined for a variety of industrial uses. Copper, an excellentconductorofelectricity, is used as electrical wire. Copper is also used in construction. It is a common material inpipes andplumbingmaterial.
Like copper, gold is also mined for industry. For example, space helmets are plated with a thin layer of gold to protectastronaut’s eyes from harmfulsolar radiation. However, most gold is used to createjewelry. For thousands of years, gold ore was mined as a basis forcurrency, or money. Most nations stopped valuing their money on thegold standardin the twentieth century.
Iron ore has been mined for thousands of years. Iron, the second-mostabundant metal on Earth, is the maincomponentof steel.Steelis a strong, valuable building material. Iron is used in everything from glass tofertilizerto thesolid-rocket boosters once used for thespace shuttleto leave Earth’satmosphere.
Metals are often associated with particular ores.Aluminum, for example, is usually found in the ore calledbauxite. Aluminum found in bauxite is used in containers, cosmetics, and medicines.
Smelting and Electrolysis
When miners findrockcontaining mineral ore, they firstextractthe rock from the earth. This can be a huge process, sometimes displacing millions of tons of dirt. The rock is then crushed by powerful machinery.
Metal is extracted from the crushed ore by one of two major methods:smelting orelectrolysis.
Smelting uses heat to separate the valuable metal from the rest of the ore. Smelting usually requires areductionagent, or another chemical, to separate metal from its ore. In the earliest smelters, the reduction agent wascarbonin the form of charcoal. Charcoal burned withhematiteore, for instance, smelts iron.
Electrolysis separates metal from ore by usingacidand electricity. Aluminum, which burns at a very high temperature, is extracted from bauxite by electrolysis. Bauxite is placed in a pool of acid, and an electricalcurrentis run through the pool. Theelectrons in the current attach tooxygenandhydrogen, the other elements in bauxite, leaving the aluminum.
Ore Genesis
Earth contains afiniteamount of ore.Ore genesis, the process by which a deposit of ore is created, is estimated to take millions of years. There are three major types of ore genesis: internal processes, hydrothermal processes, and surficial processes.
Ore canaccumulatethroughgeologicactivity, such as when volcanoes bring ore from deep in the planet to the surface. This is called an internal process. Ore can also accumulate whenseawatercirculates through cracks in Earth’s crust and deposits minerals in the areas around hydrothermal vents. This is called ahydrothermalprocess. Finally, ore can accumulate through processes that take place on the surface of Earth, such aserosion. This type of ore genesis is called asurficial process.
Ore can also fall to Earth as rockydebrisfrom elsewhere in thesolar system. These pieces of debris, entering the atmosphere asshooting stars, are calledmeteorites. Many meteorites contain large amounts of iron ore.
Ore is anonrenewable resource. Because modern societies rely so heavily on metallic ore for industry andinfrastructure,miners must constantly seek new ore deposits.Miningcompanies have explored every continent, as well as the ocean floor, in their search for valuable ore. Thisscarcitycontributes to ore's value.
Fast Fact
Aluminum
Aluminum is very rare in its pure, metal form and cannot be smelted. Until the twentieth century, aluminum was often more valuable than gold.
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Eureka!
The largest source of gold is an ore deposit located in the Witwatersrand Basin in South Africa. Roughly 40 percent of the gold ore mined on Earth has come out of mines there. Untold amounts of gold still remain hidden in the basin.
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All That Glitters
The majority of gold ore mined from the Earthmore than 80 percentbecomes jewelry. Small percentages of it go into electronic equipment, coins, and dental fillings.
Fast Fact
Steel Production
Iron ore production is often used as an indicator of a nation's economic health. For years, China has produced the most iron ore of any country on Earth.
