anorthite chemical formula

65, 272-284, CS1 maint: multiple names: authors list (, http://www.minsocam.org/ammin/AM65/AM65_272.pdf, https://en.wikipedia.org/w/index.php?title=Anorthite&oldid=900201759, Creative Commons Attribution-ShareAlike License, This page was last edited on 4 June 2019, at 03:00. Plagioclase is an abundant mineral in the Earth's crust. [4] It is more rare in surficial rocks than it normally would be due to its high weathering potential in the Goldich dissolution series. Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree.... Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. The other end member, Anorthite, contains calcium and no sodium.The intermediary members are Oligoclase, Andesine, Labradorite, and Bytownite.Oligoclase and Andesine are considered by some to be a variety of Albite rather then a separate mineral. The formula of pure anorthite is CaAl2Si2O8. Multiply all of the normative ‘mineral’ values by their respective formula weights. J.R. Goldsmith (1980): The melting and breakdown reactions of anorthite at high pressures and temperatures. Our editors will review what you’ve submitted and determine whether to revise the article. Anorthite is rare on the Earth but abundant on the Moon. Anorthite is rare on the Earth but abundant on the Moon. It is transparent to translucent and usually has small amounts of sodium and/or magnesium, potassium and iron. Omissions? Premium Membership is now 50% off! Contents[show] Mineralogy Anorthite is the calcium-rich endmember of the plagioclase solid solution series, the other endmember being albite, NaAlSi3O8. Anorthite and the sodium-bearing end-member of the system, albite (NaAlSi3O8), form a solid-solution series in which the two intermingle; thus, in nature there is a continuous chemical variation between the two compounds. It also occurs in metamorphic rocks of granulite facies, in metamorphosed carbonate rocks, and corundum deposits. Anorthite. Calculate the formula weight of plagioclase, using the An' value from #24. The minerals of the plagioclase series are listed in the table below along with their relative abundance of albite (Ab) and anorthite (An). It was first described in 1823. [6], Anorthite is the calcium-rich endmember of the plagioclase solid solution series, the other endmember being albite, NaAlSi3O8. Chemical Formula: CaAl 2 Si 2 O 8: Composition: Calcium aluminum silicate. Microcline and orthoclase are potassium feldspars (KAlSi 3 O 8), usually designated Or in discussions involving their end-member composition. Black Friday Sale! By signing up for this email, you are agreeing to news, offers, and information from Encyclopaedia Britannica. Anorthite is the calcium endmember of the plagioclase feldspar mineral series. Feldspar Ca Endmember CaAl2Si2O8. It occurs in mafic igneous rock. Anorthite is an end member and one of the rarer members of the plagioclase series. Anorthite, a feldspar mineral, calcium aluminosilicate (CaAl2Si2O8), that occurs as white or grayish, brittle, glassy crystals. There are several plagioclase feldspars in the seriesbetween albite and anorthite. Anorthite could be the member that is rarest of Plagioclase Feldspars for the Feldspar number of minerals that includes Albite, Amazonite, Andesine, Anorthite, Bytownite, Hyalophane, Labradorite, Moonstone, Oligoclase, Orthoclase, Sanidine and Sunstone. Anorthite Mineral Facts: Chemical Formula: CaAl 2 Si 2 O 8 Calcium-aluminum silicate, consisting of Silica 43.2%, alumina 36.7%, calcium 20.1%. At 1 atmosphere, anorthite melts at 1553 °C.[1]. Anorthite is rare on the Earth[5] but abundant on the Moon. See more. Anorthite is the calcium endmember of the plagioclase feldspar mineral series. Trioctahedral sheet … Anorthite is found in mafic igneous rocks. May contain some sodium replacing the calcium, but that amount must be less than 10 percent to be strictly Anorthite. Mineralogist. Anorthite is the rarest member of the Plagioclase Feldspars of the Feldspar Group of minerals that includes Albite, Amazonite, Andesine, Anorthite, Bytownite, Hyalophane, Labradorite, Moonstone, Oligoclase, Orthoclase, Sanidine and Sunstone. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solution series, more properly known as the plagioclase feldspar series. Let us know if you have suggestions to improve this article (requires login). [2] Its type localities are Monte Somma and Valle di Fassa, Italy. This article was most recently revised and updated by, https://www.britannica.com/science/anorthite, The Mineral and Gemstone Kingdom - Anorthite, Amethyst Galleries - The Mineral Anorthite. Am. Albite is the sodium-rich end member while Anorthite may be the … Anorthite is the calcium-rich endmember of the plagioclase solid solution series, the other endmember being albite, NaAlSi3O8. Anorthite by definition must contain no more than 10% sodium and no less than 90% calcium in the sodium/calcium position in the crystal structure. The chemical formula of pure anorthite is CaAl2Si2O8. Anorthite is rare on the Earth [5] but abundant on the Moon. Anorthite occurs in basic igneous rocks, as at Trentino, Italy; Södermanland, Thedeflection angle is an optical characteristic and varies according to thealbite fraction (Ab). Plagioclase is the name of a group of feldspar minerals that form a solid solution series ranging from pure albite, Na(AlSi3O8), to pure anorthite, Ca(Al2Si2O8). Albite. Tremolite formula (amphibole) Ca2Mg5Si8O22(OH)2. The In thin section, plagioclase feldspar grains often look like they’re sprinkled with dirt (PPL) or tiny confetti (XPL). Example 4.4.1.: Halite NaCl Na 22.9898 Cl 35.453 Formula weight 58.44 grams Z = 4 Avogadro's Number of unit cells contains Z (i.e. Chemical composition. The chemical formula for such a composition would be written as MgFeSiO 4. Similarly, for an olivine ... KALSi 3 O 8, and Anorthite (An) - CaAl2Si 2 O 8. 4) formula weights or … All the rock-forming feldspars are alumino silicate minerals with the general formula AT 4 O 8 in which A = potassium, sodium, or calcium (Ca); and T = silicon (Si) and aluminum (Al), with a Si:Al ratio ranging from 3:1 to 1:1. Albite belongs to the Plagioclase Feldspar group, an isomorphous solid solution series.Albite is one end member, containing sodium and no calcium. [6] Calcium is a chemical element with symbol Ca and atomic number 20. The chemical formula of pure anorthite is CaAl2Si2O8. The Plagioclase Feldspars form a string between Albite and Anorthite. Anorthite is found in mafic igneous rocks. The chemical formula of pure anorthite is Ca Al 2 Si 2 O 8. 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. ; Tamil Nadu, India; Miyake, Japan; and Franklin, N.J. For detailed physical properties, see feldspar (table). It also makes up much of the lunar highlands; the Genesis Rock is made of anorthosite, which is composed largely of anorthite. The composition of plagioclase feldspar is typicallyindicated by the general anorthite (% An) or albite (% Ab) fraction and iseasily determined by measuring the refractive index or peel angle within thecrushed particles by measuring the refraction angle under a thin section. A series between Albite and Anorthite Feldspar Group. 26. Orthoclase. Any member of this series is called a plagioclase. Foit F F, Peacor D R (1973) The anorthite crystal structure at 410 and 830 C American Mineralogist 58 665-675: 1973: 0: 1103: 0001194: Anorthite: Angel R J (1988) High-pressure structure of anorthite American Mineralogist 73 1114-1119: 1988: Val Pasmeda, Austria: 0: 293: 0001195: Anorthite The Plagioclase Feldspars form a series between Albite and Anorthite. The names of the minerals in the series are arbitrarily given based upon their relative abundance of albite and anorthite. Anorthite is found in mafic igneous rocks. Corrections? Anorthite is the calcium endmember of the plagioclase feldspar mineral series. CaAl2Si2O8. Lunar resources - Wikipedia In chemical composition and in its crystallographic and physical characters it is intermediate between albite (NaAlSi 3 O 8 ) and anorthite (CaAl 2 Si 2 O 8 ). Mineralogy. Anorthite Na0:1¡0:0Ca0:9¡1:0Al1:9¡2:0Si2:1¡2:0O8 °c 2001 Mineral Data Publishing, version 1.2 Crystal Data: Triclinic. In petrology, the plagioclase series are defined based on their percentage of albite (Ab) to anorthite … The formula of pure anorthite is CaAl 2 Si 2 O 8.It is not Radioactive. Plagioclase is a series of tectosilicate (framework silicate) minerals within the feldspar group. Feldspar K Endmember KAlSi3O8. Plagioclase: Add albite to anorthite to make plagioclase. Anorthite Anorthite is the calcium endmember of plagioclase feldspar. Anorthite is the calcic end member of the plagioclase feldspar series. Anorthite is a rare compositional variety of plagioclase. Alternate name for the plagioclase series of feldspars. Formula weight of plagioclase = (An'*278.2093)+((1-An')*262.2230) 27. Updates? Primarily a rock-forming mineral, it is used in the manufacture of glass and ceramics. The plagioclase series comprises minerals that range in chemical composition from pure NaAlSi3 O8, Albite to pure CaAl2 Si2 O8 , anorthite.Anorthite by definition must contain no more than 10% sodium and no less than 90% calcium in the sodium/calcium position in the crystal structure. Anorthite, a feldspar mineral, calcium aluminosilicate (CaAl2Si2O8), that occurs as white or grayish, brittle, glassy crystals. Plagioclase is an abundant mineral in the Earth’s crust. Feldspar Na Endmember NaAlSi3O8. Retain the albite value, but anorthite is now zero. The feldspar minerals are mixtures of sodium, potassium, and calcium aluminosilicates; they belong to a ternary system in which any mineral may be classed by its percentage of each of three pure compounds, called end-members: sodium aluminosilicate, potassium aluminosilicate, and calcium aluminosilicate. General Plagioclase Information : Chemical Formula: (Na,Ca)(Si,Al)4O8 : Composition: Molecular Weight = 270.77 gm Sodium 4.25 % Na 5.72 % Na 2 O: Calcium 7.40 % Ca 10.36 % CaO: Aluminum 9.96 % Al 18.83 % Al 2 O 3: Silicon 31.12 % Si 66.57 % SiO 2: Oxygen 47.27 % O: 100.00 % 101.48 % = TOTAL OXIDE ... Anorthite formula. Soda is usually present, in small amount, in the albite molecule, NaAlSi 3 O 8.Nearly all Anorthite contains small traces of K2O, MgO and Fe2O3. You can find the explanation on the plagioclase feldspar page. At high temperature, complete solid solution exists between Ab and Or, to form the alkali feldspar solid solution series. Anorthite also refers to plagioclase compositions with more than 90 molecular percent of the anorthite endmember. This permits us to calculate the theoretical density of any mineral from its cell volume, its formula, and its Z number. Anorthite is found in mafic igneous rocks. Anorthite is a lime feldspar, triclinic, has a hardness f 6 to 6.5 mhos, SG of 2.7 - 2.8, is white, usually, can be colorless or grayish, bluish, yellowish or reddish. Anorthite occurs in basic igneous rocks, as at Trentino, Italy; Södermanland, Swed. Anorthite is rare on the Earth but abundant on the Moon. Anorthite is the calcium-bearing end-member of the system; its symbol is An. 2.15) may be formed by solid-state reactions (French et al., 2001) or may crystallize from the melt.The mineral phase depends upon the temperature attained and the rapidity of cooling, with the BA tending to cool more slowly, as well as the chemical composition of the material and the potential for interaction between the phases involved. General Plagioclase Information : Chemical Formula: (Na,Ca)(Si,Al)4O8 : Composition: Molecular Weight = 270.77 gm Sodium 4.25 % Na 5.72 % Na 2 O: Calcium 7.40 % Ca 10.36 % CaO: Aluminum 9.96 % Al 18.83 % Al 2 O 3: Silicon 31.12 % Si 66.57 % SiO 2: Oxygen 47.27 % O: 100.00 % 101.48 % = TOTAL OXIDE Minerals in this series are a homogenous mixture of albite and anorthite. Anorthite definition, a white or gray feldspar mineral, CaAl2Si2O8, calcic plagioclase. The chemical formula of pure anorthite is Ca Al 2 Si 2 O 8. This was first shown by the German mineralogist Johann Friedrich Christian Hessel (1796–1872) in 1826. Primarily a rock-forming mineral, it is used in the manufacture of glass and ceramics. The chemical formula of pure anorthite is CaAl2Si2O8. Anorthite is found in mafic igneous rocks. Calcium (Ca) is the fourth most abundant element in the lunar highlands, present in anorthite minerals (formula ). Pyroxene chemical formula (Mg,Ca,Fe)Si2O6. 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