A group of feldspar minerals that form a solid solution series from albite (sodium aluminum silicate) to anorthite (calcium aluminum silicate). The plagioclase feldspars are found in igneous, plutonic, and metamorphic rocks. They all have the triclinic-pinacoidal crystal habit, but only Albite commonly occurs in well crystallized specimens.

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  • Plagioclase — A photomicrograph of a plagioclase crystal under cross polarized light. The plagioclase crystal shows a distinct banding effect called a Polysynthetic twinning. (unknown scale) General Category …   Wikipedia

  • plagioclase — [ plaʒjoklaz ] n. m. • 1899; du gr. plagios « oblique » et clasis « cassure » ♦ Minér. Feldspath contenant du calcium et du sodium, mais pas de potassium. ● plagioclase nom masculin (grec plagios, oblique) Aluminosilicate naturel de sodium et de… …   Encyclopédie Universelle

  • Plagioclase — Pla gi*o*clase, n. [Gr. pla gios oblique + kla^n to break.] (Min.) A general term used of any triclinic feldspar. See the Note under {Feldspar}. [1913 Webster] …   The Collaborative International Dictionary of English

  • plagióclase — s. f. [Geologia] Silicato de alumínio, sódio e cálcio, do grupo dos feldspatos. = PLAGIOCLÁSIO   ‣ Etimologia: grego plágios, a, on, oblíquo, enviesado + grego klásis, eos, quebra, fratura …   Dicionário da Língua Portuguesa

  • plagioclase — [plā′jē ō klās΄] n. [Ger plagioklas < Gr plagios (see PLAGIO ) + klasis, a cleaving, fracture < klaein, to break: see CLASTIC] any of a series of triclinic feldspars, ranging in composition from albite to anorthite and found in many rocks …   English World dictionary

  • plagioclase — plagioclastic /play jee euh klas tik/, adj. /play jee euh klays /, n. any of the feldspar minerals varying in composition from acidic albite, NaAlSi3O8, to basic anorthite, CaAl2Si2O8, found in most igneous rocks: shows twinning striations on… …   Universalium

  • Plagioclase — Grains fins de plagioclases dans roche volcanique Les plagioclases sont une importante série de silicates minéraux dans la famille des feldspaths. Plutôt que de se référer à un minéral particulier avec une composition chimique spécifique, le… …   Wikipédia en Français

  • plagioclase — [ pleɪdʒɪə(ʊ)kleɪz, plagɪəʊ ] (also plagioclase feldspar) noun a form of feldspar consisting of aluminosilicates of sodium and/or calcium, common in igneous rocks and typically white. Origin C19: from plagio + Gk klasis cleavage (because orig.… …   English new terms dictionary

  • plagioclase series — ▪ Table The plagioclase series mineral     percent albite     percent anorthite albite 100–90 0–10 oligoclase 90–70 10–30 andesine 70–50 30–50 labradorite 50–30 50–70 bytownite 30–10 70–90 anorthite 10–0 90–100 See as table: * * * …   Universalium

  • plagioclase — noun Etymology: Greek plagios oblique + klasis breaking, from klan to break more at clast Date: circa 1868 a triclinic feldspar; especially one having calcium or sodium in its composition …   New Collegiate Dictionary

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