A mineral is a naturally occurring solid chemical compound with a specific chemical composition that occurs in a pure form, as opposed to an impure form. In geology and mineralogy, the term 'mineral' is often reserved for inorganic substances found naturally in the earth's crust.

The commercially available synthetic equivalents of certain minerals are indistinguishable from the natural mineral. Artificial emeralds and sapphire stones created through industrial methods are often nearly identical to their natural counterparts in terms of size, hardness, and color.