What is a mineral

From GeoClasses

Definition of a Mineral

A mineral is a naturally occurring, inorganic crystalline substance with a chemical composition that may vary within fixed limits. Thus, any solid may be called a mineral if all of the following apply:

• it occurs in nature
• it is not an organic compound
• it has a constant (or relatively constant) chemical composition
• it has a definite atomic structure that, under appropriate conditions, exhibits a definite external crystalline form

Mineral: Halite = Salt

Common table salt is a mineral called halite. It is

Salt precipitation on the shore of Nulla Lake in central Australia.

• is naturally occuring in nature, and can form large crystals. Water evaporated in lakes in arid climates is one natural source of halite.
• it is not produced by plants or animals, simply by the evaporative concentration of water.
• its chemical composition is entirely sodium chloride (NaCl). (Find these elements in the periodic table)

Large salt crystal. Mineral name: halite. Notice the blocky crystal form.

The cubic atomic structure of the mineral halite. The green atoms represent chlorine and the grey atoms represent sodium.

• the sodium chloride molecules are bound together in a rigid, cubic structure that gives a definite crystal form.

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