anortite

Anortite is a mineral belonging to the plagioclase feldspar series. It is the calcium-rich end-member of this solid solution series, with the chemical formula CaAl2Si2O8. Anortite is characterized by its high calcium content and relatively low silica content compared to albite, the sodium-rich end-member. It typically crystallizes in the triclinic system, forming individual crystals or massive aggregates. Pure anorthite is colorless and transparent, but impurities can lead to various shades of gray, white, or even pink.

The hardness of anorthite is between 6 and 6.5 on the Mohs scale, and it has a specific gravity of approximately 2.76. Its cleavage is perfect in two directions, intersecting at nearly right angles. Anortite is a relatively rare mineral found primarily in mafic and ultramafic igneous rocks, such as gabbro and basalt. It is also a significant component of lunar anorthosites, which are the dominant rock type on the lunar highlands. In terrestrial environments, anorthite can be found in metamorphic rocks like granulites and eclogites. Its presence in igneous rocks often indicates a high-temperature crystallization environment.