name = Anorthite
category = Feldspar mineral
caption = Anorthite from Japan
formula = CaAl2Si2O8
color = White, grayish, reddish
habit = Anhedral to subhedral granular
twinning = Common
cleavage = Perfect  good 
fracture = Uneven to concoidal
tenacity = Brittle
mohs = 6
luster = Vitreous
refractive = nα = 1.573 - 1.577 nβ = 1.580 - 1.585 nγ = 1.585 - 1.590
opticalprop = Biaxial (-), 2V 78° to 83°
birefringence = δ = 0.012 - 0.013
gravity = 2.72 - 2.75
diaphaneity = Transparent to translucent
references = http://www.handbookofmineralogy.org/pdfs/anorthite.pdf Handbook of Mineralogy] [http://www.mindat.org/min-246.html Mindat] http://webmineral.com/data/Anorthite.shtml Webmineral]
Anorthite is the
calcium-rich endmember of the plagioclase solid solutionseries, the other endmember being albite, NaAlSi3O8. Anorthite also refers to plagioclase compositions with more than 90 molecularpercent of the anorthite endmember.
Anorthite is a rare compositional variety of plagioclase. It occurs in
maficigneous. It also occurs in granulitefacies metamorphic rocks, in metamorphosed carbonate rocks and corundumdeposits. Its type localities are Monte Sommaand Valle di Fassa, Italy. It was first described in 1823.
It also makes up much of the lunar highlands. Anorthite was discovered in samples from
comet Wild 2, and the mineral is an important constituent of Ca-Al-rich inclusionsin rare varieties of chondritic meteorites.
List of minerals
In-Situ Resource Utilization
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