A mineral is a naturally occurring, inorganic solid with a definite chemical composition--that may vary within limit--and an orderly internal structure.
Inorganic elements obtained from food, such as calcium, iron, magnesium, potassium and sodium, that are essential to the functioning of the human body.
The Mineralogy Database was last updated on 8/15/2009 and it contains 4,714 individual mineral species descriptions with links and a comprehensive image library.