The chemical composition of microcline is K[AlSi3O8]. It is a feldspar mineral with a triclinic system. Crystal twinning is common, and the crystals appear as blocky aggregates. Its colours are grey, white, light yellow, light red and pink. Green microcline is called amazonite. Its diaphaneity is from transparent to translucent, and the cleavage has a vitreous or pearly lustre. Its specific gravity is 2.55–2.63, the Mohs hardness is 6–5.5, and the fractures are uneven. It mainly forms in igneous rocks, particularly granite, pegmatite and syenite. It is also found in some metamorphic rocks, especially schist, as well as in hydrothermal veins and contact metamorphic zones. Microcline in pegmatite is always accompanied by quartz and albite.