A mineral is a naturally occurring, nonliving, solid substance with a definite chemical composition and an orderly arrangement of atoms. An example of a mineral is a quartz crystal.
People frequently use minerals in their everyday life. For example, pencil "lead" is actually made of graphite, a mineral that leaves a black streak. Some electronic devices also have quartz components. Walls are often made of gypsum.
Minerals can be placed into categories according to their physical properties. A physical property is a characteristic of a substance that can be observed or measured without changing the substance. Some of the physical properties, like luster and color, can be determined simply by looking at them. Other properties, like hardness and magnetism can be determined with easy tests.
Every mineral has a unique set of physical and chemical properties. These properties can be used to classify or identify the mineral. The following are examples of properties used in mineral identification.
 Composition —Composition describes the chemical makeup of a substance. Each mineral is a pure substance, but each mineral is made of a different compound. The compositions of some minerals causes them to combine chemically with other substances. For example, the mineral calcite will combine with lemon juice to form a gas, which can be seen as bubbles.
 Color —Minerals can be classified by their color. Some minerals have unusual colors. But in general, color is not the best way to identify a mineral because the same mineral may have different colors, depending on how it formed. Also, several minerals are the same color. The property of color is best used along with another property when identifying a mineral.
 Hardness —Hardness describes a mineral's ability to resist scratching or cracking. It is measured using the
Mohs' hardness scale. The mineral talc has a hardness of 1 is easily scratched by a fingernail. Diamond, which is the hardest known substance, has a hardness of 10.
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Luster
—Luster describes the way light interacts with the surface of a mineral. Different minerals have different types of luster. Some types of luster include metallic, pearly, glassy, greasy, and earthy.
 Streak
—Softer minerals will make a mark when they are scratched on an unglazed porcelain streak plate. The mineral can be classified by the color of its streak. The color of the mineral is not always the same as the color of its streak.For example, one form of the mineral hematite is metallic silver in color, but it produces a red streak. Streak is sometimes referred to as a mineral's true color .
 Cleavage
—Cleavage describes a mineral sample's natural ability to form pieces with new flat surfaces when breaking.There are different types of cleavage depending on how the mineral breaks. Not all minerals display cleavage.
 Fracture
—Fracture is the way a mineral breaks if cleavage does not occur. If the break has a smooth curved surface it is called a conchoidal fracture ; most minerals fracture irregularly and leave an uneven, flaky, or jagged break.

 Magnetism
—A few minerals have strong attractions to magnets. In addition to being attracted to magnets, one mineral acts as a magnet itself. You can check to see if a mineral behaves like a magnet by checking to see if iron filings are attracted to it.
 Fluorescence —Some minerals fluoresce in the presence of ultraviolet light. Mineral fluorescence occurs when the mineral takes in light from the surroundings and then emits light of a lower energy (and therefore a different color).Most minerals fluoresce only if they contain certain impurities. Fluorescence should not be used as the only criterion for identifying a mineral, as there are several factors that help determine whether or not a mineral will fluoresce.
The following table compares the properties of ten common minerals.
Minerals are formed during a number of different processes, including the following:
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 the cooling of molten materials the evaporation of liquids high temperature and high pressure processes on other minerals
Igneous rocks containing various minerals form when magma cools below Earth's surface, or magma erupts from the Earth as lava and then cools. Common minerals that form under these circumstances include quartz, magnetite, potassium feldspars, and micas.
Some minerals form when solid mineral precipitates are created within a solution. Minerals that often form in this manner include halite and gypsum.
Metamorphic processes can also generate a number of different minerals. When existing minerals are subjected to high temperatures and pressures, sometimes new minerals are formed. The minerals diamond, garnet, and chlorite usually form in this manner.
Mineral formation generally takes place over a very long period of time. Scientists wishing to study mineral formation can model it in the lab. For example, the formation of halite deposits can be modeled by evaporating the water from a concentrated solution of sodium chloride (salt).

Each type of mineral has its own chemical makeup and its own set of physical properties. The properties of a mineral determine its usefulness for different purposes. Minerals are nonrenewable resources that must be conserved.
Minerals are naturally occurring elements or chemical compounds that form from sedimentary, igneous, metamorphic, and decomposition processes. Each mineral has a unique chemical composition, which gives it a unique set of physical properties. These properties make the minerals useful for different purposes. Some of the items made from minerals are listed below.
Jewelry
—Gemstones are minerals that can be cut and polished and used in jewelry. Emeralds, rubies, and garnets are some examples of gemstones. Gold, which is also often used to make jewelry, is also a mineral. Items made of precious metals (such as gold) and gems (such as emeralds, rubies or garnets) are often expensive because they are rare.
Aluminum products —Bauxite, a mineral that contains aluminum, is mined and processed to produce aluminum metal that is used to make drink cans and many other useful objects.
Glass
—Quartz and silica sand are used in making glass.
Fertilizers and animal feed
—Phosphate is used in plant fertilizers and animal feed.
Building materials —Feldspar is used in bath tiles, abrasive cleaning supplies and roofing shingles.
Television & computer components
—Quartz and feldspar are used in manufacturing televisions, computer screens, and integrated circuits.
Minerals are nonrenewable resources because they form on a geologic timescale. Since minerals are useful for humans and society, it is important that we work toward making the Earth's supply of minerals last. We can conserve minerals by recycling, reducing the rates at which we mine new minerals, and developing substitutions for minerals.
Recycling enables humans to use resources more than once instead of having to obtain more fresh resources from the environment. For example, bauxite is a mineral that contains aluminum and is used to manufacture soft drink cans. To reduce the current rate of bauxite depletion, humans can recycle more aluminum cans instead of mining more bauxite.
Reducing rates of mining will allow more minerals to be available to future generations. Recycling will help play a role in reducing the amount of new minerals being mined.
Developing mineral substitutes allows other materials to be used instead of minerals, which lowers the overall need for minerals.