• ore
    The computer on which you're reading this contains a minute amount of gold ore.

    Photograph by W. Robert Moore

    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.

    Aluminum is very rare in its pure, metal form and cannot be smelted. Until the twentieth century, aluminum was often more valuable than gold.

    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.

    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.

    Ore is a deposit in the Earths crust of one or more valuable minerals. The most valuable ore deposits contain metals crucial to industry and trade, like copper, gold, and iron.

    Copper ore is mined for a variety of industrial uses. Copper, an excellent conductor of electricity, is used as electrical wire. Copper is also used in construction. It is a common material in pipes and plumbing material.

    Like copper, gold is also mined for industry. For example, space helmets are plated with a thin layer of gold to protect astronauts eyes from harmful solar radiation. However, most gold is used to create jewelry. For thousands of years, gold ore was mined as a basis for currency, or money. Most nations stopped valuing their money on the gold standard in the twentieth century.

    Iron ore has been mined for thousands of years. Iron, the second-most abundant metal on Earth, is the main component of steel. Steel is a strong, valuable building material. Iron is used in everything from glass to fertilizer to the solid rocket boosters needed for the space shuttle to leave the Earths atmosphere.

    Metals are often associated with particular ores. Aluminum, for example, is usually found in the ore called bauxite. Aluminum found in bauxite is used in containers, cosmetics, and medicines.

    Smelting and Electrolysis

    When miners find rock containing mineral ore, they first extract the 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 or electrolysis.

    Smelting uses heat to separate the valuable metal from the rest of the ore. Smelting usually requires a reduction agent, or another chemical, to separate metal from its ore. In the earliest smelters, the reduction agent was carbon in the form of charcoal. Charcoal burned with hematite ore, for instance, smelts iron. Charcoal burned with cuprite ore smelts copper.

    Electrolysis separates metal from ore by using acid and 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 electrical current is run through the pool. The electrons in the current attach to oxygen and hydrogen, the other elements in bauxite, leaving the aluminum.

    Ore Genesis

    Earth contains only a finite amount of ore. Ore genesis, the process by which a deposit of ore is created, takes millions of years. There are three major types of ore genesis: internal processes, hydrothermal processes, and surficial processes.

    Ore can accumulate through geologic activity, such as when volcanoes bring ore from deep in the Earth to the surface. This is called an internal process. Ore can also accumulate when seawater circulates through cracks in the Earths crust and deposits minerals in the areas around hydrothermal vents. This is called a hydrothermal process. Finally, ore can accumulate through processes that take place on the surface of the Earth, such as erosion. This type of ore genesis is called a surficial process.

    Ore can also fall to Earth as rocky debris from the solar system. These pieces of debris, entering the atmosphere as shooting stars, are called meteorites. Many meteorites contain large amounts of iron ore.

    Ore is a nonrenewable resource. Because modern societies rely so heavily on metallic ore for industry and infrastructure, miners must constantly seek new ore deposits. Mining companies have explored every continent, as well as the ocean floor, in their search for valuable ore. This scarcity contributes to ores value.

  • Term Part of Speech Definition Encyclopedic Entry
    abundant Adjective

    in large amounts.

    accumulate Verb

    to gather or collect.

    acid Noun

    chemical compound that reacts with a base to form a salt. Acids can corrode some natural materials. Acids have pH levels lower than 7.

    aluminum Noun

    silvery, reflective metallic element with the symbol Al.

    astronaut Noun

    person who takes part in space flights.

    atmosphere Noun

    layers of gases surrounding a planet or other celestial body.

    Encyclopedic Entry: atmosphere
    bauxite Noun

    mineral containing aluminum.

    carbon Noun

    chemical element with the symbol C, which forms the basis of all known life.

    component Noun


    conductor Noun

    material that transfers heat, light, electricity, or sound.

    copper Noun

    chemical element with the symbol Cu.

    crucial Adjective

    very important.

    crust Noun

    rocky outermost layer of Earth or other planet.

    Encyclopedic Entry: crust
    cuprite Noun

    mineral containing copper.

    currency Noun

    money or other resource that can be used to buy goods and services.

    current Noun

    steady, predictable flow of fluid within a larger body of that fluid.

    Encyclopedic Entry: current
    debris Noun

    remains of something broken or destroyed; waste, or garbage.

    displace Verb

    to remove or force to evacuate.

    electricity Noun

    set of physical phenomena associated with the presence and flow of electric charge.

    electrolysis Noun

    system of extracting metal from ore by using acid and electricity.

    electron Noun

    negatively charged particle in an atom.

    erosion Noun

    act in which earth is worn away, often by water, wind, or ice.

    Encyclopedic Entry: erosion
    extract Verb

    to pull out.

    fertilizer Noun

    nutrient-rich chemical substance (natural or manmade) applied to soil to encourage plant growth.

    finite Adjective

    limited and not renewable.

    geologic Adjective

    having to do with the physical formations of the Earth.

    gold Noun

    valuable chemical element with the symbol Au.

    gold standard Noun

    system where currency is valued by its worth in gold.

    hematite Noun

    mineral containing iron.

    hydrogen Noun

    chemical element with the symbol H.

    hydrothermal Adjective

    related to hot water, especially water heated by the Earth's internal temperature.

    industry Noun

    activity that produces goods and services.

    infrastructure Noun

    structures and facilities necessary for the functioning of a society, such as roads.

    iron Noun

    chemical element with the symbol Fe.

    jewelry Noun

    ornaments and decorations worn on the body.

    metal Noun

    category of elements that are usually solid and shiny at room temperature.

    meteor Noun

    rocky debris from space that enters Earth's atmosphere. Also called a shooting star or falling star.

    Encyclopedic Entry: meteor
    meteorite Noun

    type of rock that has crashed into Earth from outside the atmosphere.

    Encyclopedic Entry: meteorite
    mine Verb

    to extract minerals from the Earth.

    miner Noun

    person who excavates metal or other materials from the Earth.

    mineral Noun

    inorganic material that has a characteristic chemical composition and specific crystal structure.

    mining Noun

    process of extracting ore from the Earth.

    nonrenewable resource Noun

    natural resource that exists in a limited supply.

    ore Noun

    deposit in the Earth of minerals containing valuable metal.

    Encyclopedic Entry: ore
    ore genesis Noun

    process by which a deposit of ore is created.

    oxygen Noun

    chemical element with the symbol O, whose gas form is 21% of the Earth's atmosphere.

    pipe Noun

    hollow tube used to transport liquids or gases.

    plumbing Noun

    system of pipes for transporting liquids to and from a building.

    reduction Noun


    rely Verb

    to depend on.

    rock Noun

    natural substance composed of solid mineral matter.

    scarcity Noun

    situation that arises when demand for a good or service is greater than the supply of that good or service.

    seawater Noun

    salty water from an ocean or sea.

    shooting star Noun

    rocky debris from space that enters Earth's atmosphere. Also called a meteor.

    smelt Verb

    to separate metal from ore by using heat.

    solar radiation Noun

    light and heat from the sun.

    solar system Noun

    the sun and the planets, asteroids, comets, and other bodies that orbit around it.

    solid rocket booster Noun

    instrument used to launch a large object, such as the space shuttle, beyond Earth's atmosphere.

    space shuttle Noun

    vehicle used to transport astronauts and instruments to and from Earth.

    steel Noun

    metal made of the elements iron and carbon.

    surficial process Noun

    process by which a deposit of ore is created by movement on the Earth's surface, such as erosion.

    tin Noun

    chemical element (metal) with the symbol Sn.

    trade Noun

    buying, selling, or exchanging of goods and services.

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