Minerals A naturally occurring, homogeneous inorganic solid substance having a definite chemical composition and characteristic crystalline structure, color, and hardness.

Rock-forming Minerals Making up the majority of the Earth's crust, rock is usually defined as a mixture of minerals. There are several rock-forming minerals.

Silicate Minerals

Non-silicate Minerals rock salt—a rock dominantly composed of sodium chloride (NaCl - the mineral halite). Rock salt is an evaporite formed in restricted basins with an inflow of seawater located in an arid environmental setting. gypsum—a mineral composed of hydrous calcium sulfate (CaSO 4 -2H 2 O); an evaporite mineral used in the manufacture of plaster. calcite—a common rock-forming mineral consisting of calcium carbonate—CaCO 3. Calcite can be white, colorless (transparent), or slightly colored, commonly yellow, by other inclusion of traces of other elements. Calcite is a major constituent of sedimentary rocks such as limestone, chalk, and travertine, and in the metamorphic rock form, marble. dolomite—A white or light-colored mineral, essentially CaMg(CO 3 ) 2, commonly found in association with limestone or marble. Dolomite is a common replacement mineral in limestone that has been exposed the high magnesium content brine fluids. hematite—A reddish, steel gray, or black mineral consisting of ferric oxide (Fe2O 3 ). limonite—An amorphous orange to brownish mineral consisting of a mixture of hydrated ferric oxides, important as an iron ore. Rust on iron vehicles is essentially limonite. magnetite—a gray-black magnetic mineral that consists of iron oxide (Fe3O 4 ) and is an important form of iron ore. pyrite—a brass-colored mineral, FeS 2, occurring widely and used as an iron ore and in producing sulfur dioxide for sulfuric acid. Also called fool's gold, iron pyrites

Hardness of Minerals

Igneous Rock Formation

Igneous Rock Classification Igneous rocks are classified based on the grain size (texture) and chemical composition (mineral types). Phaneritic igneous rocks have large mineral crystals because they cool slowly. Aphanitic igneous rocks have small mineral crystals because they cool quickly.

Aphanitic (Rhyolite) Phaneritic (Granite)

Sedimentary Rock Formation Sedimentary rocks are types of rock that are formed by the deposition of material within bodies of water at the Earth's surface. Sediments can harden into sedimentary rock in two ways: Pressure-as layer after layer of sediments are deposited, the lower layers are pressed together tightly under the weight of the layers above. Cementing-some sediments are glued together by minerals dissolved in water.

Sedimentary Rock Classification

Metamorphic Rock Formation Metamorphic rocks are created by the physical or chemical alteration of an existing igneous or sedimentary material by heat and pressure.

Metamorphic Rock Classification

The Rock Cycle