epidote

epidote
—epidotic /ep'i dot"ik/, adj.
/ep"i doht'/, n.
a mineral, calcium aluminum iron silicate, Ca2(Al, Fe)3Si3O12(OH), occurring in green prismatic crystals.
[1800-10; < F épidote < Gk *epidotós given besides, increased (verbid of epididónai), equiv. to epi- EPI- + dotós given (verbid of didónai)]

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Any of a group of colourless to green or yellow-green silicate minerals with the general chemical formula A2B3(SiO4)(Si2O7)O(OH), in which A is usually calcium (Ca) and B is generally aluminum (Al), although other elements are sometimes substituted.

The epidote minerals occur as reaction products of other (earlier) minerals in low-grade (formed under relatively low-temperature, low-pressure conditions), regionally metamorphosed rocks, where their occurrence is used as an indicator of metamorphic grade.

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 any of a group of colorless to green or yellow-green silicate minerals with the general chemical formula A2B3(SiO4)(Si2O7)O(OH), in which A is usually calcium (Ca), though manganese (Mn) or cerium (Ce) is sometimes substituted; and B is generally aluminum (Al), with the main substitution being ferric iron (Fe+3). Structurally the epidote group consists of chains of AlO6 and Al4(OH)2 octahedra linked by independent SiO4 and Si2O7 groups. The A atoms are in eight-fold coordination between the chains. Members of the epidote group include epidote (A = Ca, B = Al,Fe); clinozoisite (A = Ca, B = Al, monoclinic); zoisite (A = Ca, B = Al, orthorhombic); piemontite (A = Ca, B = Al,Mn,Fe); allanite (A = Ca,Mn, Ce, B = Fe,Al).

      The epidote group occurs as secondary minerals in low-grade regionally metamorphosed rocks where its occurrence is used as an indicator of metamorphic grade. Members of the group are also produced during metamorphism of mafic igneous rocks. In some cases, they may occur as a product of hydrothermal alteration of plagioclase feldspar. Manganese-rich piemontite is associated with manganese deposits of metasomatic origin. For detailed physical properties, see silicate mineral (table).

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Universalium. 2010.

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  • epidote — [ep′ə dōt΄] n. [Fr épidote < Gr epididonai, to give besides, increase < epi , over + didonai, to give (see DATE1): so named by R. J. Haüy (1743 1822), Fr mineralogist; from the enlarged base of some of the crystal forms] hydrous calcium… …   English World dictionary

  • Epidote — Infobox mineral name = Epidote category = Silicate mineral boxwidth = boxbgcolor = imagesize = caption = Epidote crystals formula = Ca2Al2(Fe3+;Al)(SiO4)(Si2O7)O(OH) molweight = color = Pistachio green, yellow green, greenish black habit =… …   Wikipedia

  • epidote — noun Etymology: French épidote, from Greek epididonai to give in addition, from epi + didonai to give more at date Date: 1808 a yellowish green mineral Ca2(Al,Fe)3Si3O12OH usually occurring in grains or columnar masses and sometimes used as a… …   New Collegiate Dictionary

  • épidote — (é pi do t ) s. m. Sorte de minéral qui se présente sous la forme d aiguilles aplaties ; c est un silicate. ÉTYMOLOGIE    Épidote, qui a reçu un accroissement ou allongement dans un sens, et provenant de deux mots grecs se traduisant par : sur et …   Dictionnaire de la Langue Française d'Émile Littré

  • epidote — [ ɛpɪdəʊt] noun a lustrous yellow green mineral consisting of a silicate of calcium, aluminium, and iron. Origin C19: from Fr. épidote, from Gk epididonai give additionally (because of the length of the crystals) …   English new terms dictionary

  • epidote — ep•i•dote [[t]ˈɛp ɪˌdoʊt[/t]] n. mir a mineral, hydrous calcium aluminum iron silicate, Ca2(Al, Fe)3Si3O12(OH), occurring in green prismatic crystals or in masses • Etymology: 1800–10; < F épidote < Gk *epidotós given besides, increased ep… …   From formal English to slang

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