anorthite


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Related to anorthite: labradorite

anorthite

(ănôr`thīt): see feldsparfeldspar
or felspar
, an abundant group of rock-forming minerals which constitute 60% of the earth's crust. Chemically the feldspars are silicates of aluminum, containing sodium, potassium, iron, calcium, or barium or combinations of these elements.
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anorthite

[ə′nȯr‚thīt]
(mineralogy)
The white, grayish, or reddish calcium-rich end member of the plagioclase feldspar series; composition ranges from Ab10 An90 to Ab0 An100, where Ab = NaAlSi3O8 and An = CaAl2Si2O8. Also known as calciclase; calcium feldspar.
References in periodicals archive ?
Feldspars (plagioclase and K-feldspar) and chlorite (clinochlore and daphnite) are predominantly dissolved (anorthite will be excluded from discussion because it was added to fit the low concentration of Ca).
Enst: enstatite; Qz: quartz; Mul: mullite; Cris: cristobalite; Hem: Hematite; Anor: anorthite.
Substance Heating rates/ (chemical composition) ([degrees]C/min) Room 5 10 20 temperature Quartz 10.80 4.00 4.20 3.20 (Si[O.sub.2]) (%) Kaolinite ([Al.sub.2][Si.sub.2] 11.60 0 0 0 [O.sub.5][(OH).sub.4]) (%) Microcline (KAl[Si.sub.3] 4.50 2.70 5.10 3.30 [O.sub.8]) (%) Anorthite (Ca[Al.sub.2] 73.00 93.30 90.70 93.50 [Si.sub.2][O.sub.8]) (%) Calcium carbonate 0 0 0 0 (CaC[O.sub.3]) (%) Substance Heating rates/ (chemical composition) ([degrees]C/min) 30 40 50 Quartz 1.80 11.50 7.50 (Si[O.sub.2]) (%) Kaolinite ([Al.sub.2][Si.sub.2] 0 0 0 [O.sub.5][(OH).sub.4]) (%) Microcline (KAl[Si.sub.3] 3.70 6.50 29.70 [O.sub.8]) (%) Anorthite (Ca[Al.sub.2] 94.50 80.10 60.90 [Si.sub.2][O.sub.8]) (%) Calcium carbonate 0 1.90 1.90 (CaC[O.sub.3]) (%)
The chemical heterogeneity of plagioclase is also manifested in marked core to rim zoning patterns within a single crystal (e.g., anorthite from [An.sub.61] to [An.sub.10]).
Mole transfers of the reactive phases in mmol [L.sup.-1] Mole Reactive phase Chemical formula transfer Ca[X.sub.2] Ca[X.sub.2] -3.934 Mg[X.sub.2] Mg[X.sub.2] 1.965 NaX NaX 3.938 KX KX 0.000 [CH.sub.4(g)] [CH.sub.4(g)] -1.401 C[0.sub.2(g)] C[O.sub.2(g)] 4.781 Sulfur S 1.868 Albite NaAI[Si.sub.3[O.sub.8] -2.315 Anorthite Ca[Al.sub.2][Si.sub.2][O.sub.8] 3.748 K-feldspar [Kal.sub.3][Si.sub.3][0.sub.8] 2.315 K-mica [Kal.sub.3][Si.sub.3][O.sub.10][(OH).sub.2] -2.499
Anhydrite, sillimanite, corundum, hematite, and anorthite were also identified in small concentrations (less than 1%).
The phase composition of the samples of ceramic tiles is represented mainly by quartz, anorthite and a small amount of hematite and almost the same for all investigated compositions.
Lignite Giral samnple 2 Table 1 Mineral matter % present Quartz (Si[O.sub.2]) 1.2 Anorthite 3.0 Diopside 2.5 Maghemite 3.9 Hematite 10.5 Anhydrite 78.4 Hexahydrite 0.5 Total 100.0
However, quartz, feldspar (such as albite/ anorthite), several clay minerals (such as micas and illites, chamosite, chlorites, kaolinite and biotite), bayerite and calcite were common in sediment samples.
One of the Chandrayaan 1's findings, reported in September 2009, was a confirmation of the mineral anorthite, rich in calcium plagioclase.