 Minerals are naturally occurring substances.  They are often solid with a definite chemical composition.  They have an orderly arrangement of atoms, ions, and molecules that are in a crystalline structure.  Most are inorganic.

 Minerals can be formed in one of following ways: a. Solidification from a melt b. Precipitation from a water solution c. Diffusion through a solid d. Metabolism of organisms e. Precipitation from a gas

 There are close to 4,000 known types of minerals.  Each has a name with distinctive physical properties.  These properties include: color, streak, luster, hardness, specific gravity, crystal habit, and cleavage.

 These physical properties reflect the mineral’s chemical composition and crystal structure.  These physical properties can be used to identify minerals.

 Minerals can be grouped into classes according to their chemical composition for identification.  These classes include: silicates, oxides, sulfides, sulfates, halides, carbonates, and native metals.

 Silicate minerals are the most common on Earth.  A silicon-oxygen tetrahedron, which is a silicon atom surrounded by four oxygen atoms, is the building block of silicate minerals.  Groups of silicates are distinguished from one another by how the silicon-oxygen tetrahedra that constitute them are linked.

 Gemstones are minerals known for beauty and how rare they are.  Facets can be cut into them gems so they can be used in jewelry.  Faceting is done by grinding and polishing the gemstone on a faceting machine.