A plagioclase feldspar, the second member of the Albite-Anorthite solid solution series. Primarily found as small crystals in impure marble. Oligoclase contains a small amount of calcium substituting for some of the sodium in its formula. Oligoclase with reddish-golden inclusions found in Norway and Canada is called sunstone. ,Chemical composition: Sodium calcium aluminum silicate, NaCaAlSiO ,Physical properties: Mohs Hardness: 6.0 Specific gravity: 2.65 Color: white, yellow, reddish-gray Luster: glassy Fracture: conchoidal Cleavage: two good at about 94º to each other Habit: Triclinic - pinacoidal. Usually twinned and striated, but this may not be visible to the unaided eye.

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  • Oligoclase — Catégorie IX : silicates[1] Oligoclase Chihuahua, Mexico …   Wikipédia en Français

  • Oligoclase — from Chihuahua, Mexico General Category plagioclase, feldspar, tectosilicate …   Wikipedia

  • Oligoclase — Ol i*go*clase, n. [Oligo + Gr. ? fracture, fr. ? to break.] (Min.) A triclinic soda lime feldspar. See {Feldspar}. [1913 Webster] …   The Collaborative International Dictionary of English

  • oligoclase — ● oligoclase nom féminin Feldspath appartenant à la série des plagioclases, très répandu dans les roches cristallines …   Encyclopédie Universelle

  • oligoclase — [äl′i gōklās΄] n. [Ger oligoklas < Gr oligos (see OLIGO ) + klasis, a fracture (see CLASTIC), in contrast to ORTHOCLASE, because cleavage differs slightly from 90°] a plagioclase feldspar whose composition corresponds to 70 to 90 percent… …   English World dictionary

  • oligoclase — oligoklazas statusas T sritis chemija apibrėžtis Mineralas. formulė (Na,Ca)[(Si,Al)AlSi₂O₈] atitikmenys: angl. oligoclase rus. олигоклаз …   Chemijos terminų aiškinamasis žodynas

  • oligoclase — noun Etymology: German Oligoklas, from olig olig + Greek klasis breaking, from klan to break more at clast Date: 1832 a mineral of the plagioclase series …   New Collegiate Dictionary

  • oligoclase — /ol i goh klays /, n. Mineral. a kind of plagioclase feldspar occurring commonly in white crystals, sometimes shaded with gray, green, or red. [1825 35; OLIGO + CLASE] * * *       the most common variety of the feldspar mineral plagioclase (q.v.) …   Universalium

  • oligoclase — (entrée créée par le supplément) (o li go kla z ) s. f. Terme de minéralogie. Silicate double d alumine et de soude. C est une substance blanchâtre ou gris verdâtre, qui se présente en petites masses lamellaires …   Dictionnaire de la Langue Française d'Émile Littré

  • oligoclase — [ ɒlɪgə(ʊ)kleɪz] noun a feldspar mineral common in siliceous igneous rocks, consisting of a sodium rich plagioclase. Origin C19: from oligo + Gk klasis breaking (because thought to have a less perfect cleavage than albite) …   English new terms dictionary

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