In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.
An element or chemical compound that is normally crystalline, formed as a result of geological processes
Naturally occurring usually inorganic substance that has a definite chemical composition and a crystal structure
A naturally occurring substance with a characteristic chemical composition expressed by a chemical formula; may occur as individual crystals or may be disseminated in some other material or rock.
Any naturally occurring inorganic material that has a (more or less) definite chemical composition and characteristic physical properties.