composition

Chemical composition, together with conditions of temperature and pressure, determines the internal structure of minerals, and hence determines mineral identity (chemistry + structure) and properties. Compositions range from pure elements to complex silicates.

Crystal structures reflect the regular internal atomic or ionic arrangement of component elements, and fit into one of fourteen Bravais lattices and one of six crystal systems.

Based on elemental chemical composition, minerals are divided into anion-based classes according to the Dana classification system: in order of relative abundance: ◊ silicates – most rocks comprise >95% silicates ◊ amphiboles, biotite, chlorites, epidote, feldspars, micas, olivine, pyroxenes, quartz ◊◊ aluminosilicates (kyanite, sillimanite, zeolites) ◊ carbonates ◊ sulfates ◊ halides ◊ oxides ◊ sulfides ◊ phosphates ◊ elements