MINERALS ARE VALUABLE RESOURCES Minerals are basic building blocks of Earth.
Minerals have many uses in industry and in the arts. • Necessary to our modern way of life • Sources of metals for cars and airplanes • Quartz and feldspar for glass • Fluorite and calcite for toothpaste • Silver compounds for photographic film • Mica and talc for paint • Birthstone tradition is hundreds of years old • Ancient Egyptians used gems (particularly beautiful minerals) in jewelryat least 4000 years ago • Found rough and irregularly shaped in nature • Gem cutter grinds it into the desired shape and polishes it. • Increases beauty and sparkle. • Material used to shape and polish a gemstone must be at least as hard as the gemstone itself. • Metals are used in jewelry making and other decorative arts. • Gold and silver are usually combined with copper to increase their hardness
Minerals form in several ways. • Minerals form by natural processes within Earth or on Earth’s surface • Develop when atoms of one or more elements join together and crystals grow • Depends in part on which elements are present • Temperature and pressure affect which minerals form • Water with substances in it evaporates • Salt water evaporates leaving halite (table salt) • Gypsum often forms as water evaporates. • Hot water within Earth’s crust moves through rocks and dissolves minerals, then cools and the dissolved minerals separate and become solid. • Minerals can be moved from one place to another • Gold that is dissolved can fill cracks in rocks when it becomes solid again • Minerals can form that are different from the ones that dissolved • Lead from the mineral galena can become part of the mineral wulfenite
Minerals form in several ways. • Minerals grow from magma which contains the types of atoms found in minerals • The atoms join together to form different minerals as magma cools • Minerals also form as lava cools. • Quartz is one of the many minerals that crystallize from magma and lava. • Heat and pressure within Earth cause new minerals to form • Bonds between atoms break and join again. • Garnet can grow and replace the minerals chlorite and quartz • The element carbon is present in some rocks • At high temperatures carbon forms the mineral graphite (pencil lead) • Organisms produce minerals. • Ocean animals (oysters, clams) produce calcite and other carbonate minerals to form shells. • Your body produces apatite in your bones and teeth
Magma Lava Both Contains all types of atoms that are found in minerals As magma cools, different minerals form Molten rock that reaches Earth’s surface Molten rock inside the Earth
Minerals form in several ways. Q. In what two ways can substances dissolved in water eventually form minerals? • Water can evaporate leaving the substances behind to crystallize into minerals. • The substances can be dissolved in hot water, but can separate out when the water cools.
Many minerals are mined. • Minerals must be removed from the ground. • Some are found near Earth’s surface • Others lie deep underground • Most are combined with other minerals in rocks • Must be enough of the mineral present in a rock to be worth mining • Ores are rocks that contain enough mineral to be mined for a profit • Surface Mining recovers minerals at or near Earth’s surface • Some minerals are very dense and can build up in riverbeds as less dense minerals are carried away • In panning unwanted minerals that are less dense are washed away • The gold and other dense minerals stay in the bottom of the pan and can then be further separated. • In bigger riverbed mining operations, miners use machines to dig out and separate the valuable minerals.
Many minerals are mined. • Strip miningoccurs when miners strip away plants, soil, and unwanted rocks from Earth’s surface then use special machines to dig out an ore. • Open-pit mining involves removing the surface layer of soil then useing explosives to break up the underlying rock and recover the ore • Roads are built up the sides of the pit to carry ore to the surface. • Copper and iron
Surface mining In panning, a miner washes away some minerals, while heavier minerals remain in the pan. In strip mining, miners remove plants, soil, and unwanted rocks, then use special machines to dig out the ore. In open-pit mining, miners remove the surface layer of soil, then use explosives to break up the rock and free the ore.
Deep mining • Deep-mining methods are needed when an ore lies far below Earth’s surface. • Used to obtain many minerals. • Miners dig an opening to reach deep ore • From the main passage, miners blast, drill, cut, or dig • Level passages are cut in hills or mountains to reach ore • Miners keep digging farther into the hill or mountain • Vertical passages are cut to reach an ore that lies underground in a flat area or under a mountain • Ore is removed in layers