Habit: granular, euhedral crystals, striated.
Color: white, gray, or reddish white.
Diaphaneity: transparent to translucent.
Luster: pearly, vitreous (i.e., glassy).
Cleavage: (001) perfect, (010) good.
Twinning: Albite [010], Pericline [010].
Fracture: uneven.
Streak: white.
Occurrence: magmatic and metamorphic rocks.
Anorthite is one of the four components of feldspars,
expressed as CaAl2Si2O8. Feldspars are a group of
silicate materials, They are the most abundant minerals
in the earth’s crust. Anorthite or pure calcium feldspar
belongs to the plagioclase subdivision of feldspars.
