Mineral Species

a natural chemical compound characterized by a definite crystalline structure. The species includes the aggregate of individual minerals that have the same (or monotypic) crystalline structure and chemical elemental composition. The chemical elemental composition may vary within definite limits as a result of isomorphic substitution of crystallochemical analogues for the main elements: for example, wolframite and its varieties huebnerite Mn[Wo₄] and ferberite Fe[Wo₄], plagioclase and its varieties albite and anorthite, and olivine and its varieties forsterite and fayalite.