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Anorthite
Anorthite

Anorthite

Anorthite

A species of Minerals, Also known as Anorthoîte, Basic Plagioclase, Beffonite, Calcic plagioclase, Calcium Feldspar, Didymolite, Latrobite, Lime-feldspar

Anorthite is the calcium endmember of the plagioclase feldspar mineral series. The chemical formula of pure anorthite is CaAl2Si2O8. Anorthite is found in mafic igneous rocks. Anorthite is rare on the Earth but abundant on the Moon.

Hardness
Hardness:

6 - 6.5

Density
Density:

2.76 g/cm³

General Info About Anorthite

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Physical Properties of Anorthite

Colors
Colourless, reddish grey, white
Streak
White
Hardness
6 - 6.5 , Hard
Density
2.76 g/cm³, Normal Weight
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Chemical Properties of Anorthite

Formula
Ca(Al2Si2O8)
Elements listed
Al, Ca, O, Si
Common Impurities
Ti,Fe,Na,K

Optical Properties of Anorthite

Refractive Index
1.575-1.588
Birefringence
0.013
Optical Character
Biaxial negative

Characteristics of Anorthite

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Formation of Anorthite

Anorthite is a rare compositional variety of plagioclase. It occurs in mafic igneous rock. It also occurs in metamorphic rocks of granulite facies, in metamorphosed carbonate rocks, and corundum deposits. Its type localities are Monte Somma and Valle di Fassa, Italy. It was first described in 1823. It is more rare in surficial rocks than it normally would be due to its high weathering potential in the Goldich dissolution series. It also makes up much of the lunar highlands; the Genesis Rock is made of anorthosite, which is composed largely of anorthite. Anorthite was discovered in samples from comet Wild 2, and the mineral is an important constituent of Ca-Al-rich inclusions in rare varieties of chondritic meteorites.

Cultural Significance of Anorthite

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Mineralogy and Petrology of Anorthite

Anorthite is the calcium-rich endmember of the plagioclase solid solution series, the other endmember being albite, NaAlSi3O8. Anorthite also refers to plagioclase compositions with more than 90 molecular percent of the anorthite endmember. At 1 atmosphere, anorthite melts at 1553 °C.

Common Questions People Also Ask

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