3.2: What is a Mineral?

What Is a Mineral?

A mineral Links to an external site. is defined as any naturally occurring, inorganic solid with a definite chemical composition and a characteristic crystalline structure. Let’s break down this definition down. 

•  Naturally occurring, means that anything synthetic (human-made), does not count as a mineral. 
• To be an inorganic solid, the mineral must not be composed of the complex carbon molecules that are characteristic of life and must be in the solid state, rather than vapor or liquid. This means that water, a liquid, is not a mineral, while water-ice, a solid, would be a mineral, provided it is out in nature and not synthetic. 
• A definite chemical composition refers to a definable chemical formula. Some minerals will have short chemical formulas, like Halite (NaCl or sodium chloride). For other minerals, like Olivine (Mg,Fe)₂SiO₄ or a magnesium iron silicate), the chemical formula becomes involved, as certain elements may substitute for another of similar size and charge. 
• The atoms within minerals are lined up in an orderly fashion, so that the characteristic crystalline structure is just an outward manifestation of the internal atomic arrangement.