microcline


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Related to microcline: sanidine, orthoclase

microcline:

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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Microcline

 

a mineral of the feldspar group. It is a triclinic K-Na feldspar with the chemical composition (K, NaXAlSiaOg]; it contains negligible quantities of Ca, Ba, Fe, Rb, and Cs. Microcline often forms perthites, which are microclines with small albite intergrowths. It occurs as individual grains, grain aggregates, prismatic crystals, or single crystals with a volume up to several m3. The mineral has a hardness of 6–6.5 on Mohs’ scale and a density of 2,540–2,570 kg/m3. It may be pink, brownish yellow, reddish white, or pinkish red; less frequently it is white or bluish green (amazonite, or amazonstone). Microcline has a vitreous or pearly luster. A thin section of the mineral under the microscope shows multiple twins, forming the characteristic microclinic grating structure.

Microcline is a typical rock-forming mineral contained in granite, granodiorite (syenite), pegmatite, and gneiss. It is the primary raw material used by the ceramics industry (porcelain, glazed pottery, and industrial ceramics). Amazonite is used as an ornamental stone.

WORKS

Kostov, I. Mineralogiia. Moscow, 1971. (Translated from English.)

microcline

[′mī·krə‚klīn]
(mineralogy)
KAlSi3O8 A triclinic potassium-rich feldspar, usually containing minor amounts of sodium; may be clear, white, pale-yellow, brick-red, or green, and is generally characterized by crosshatch twinning.
References in periodicals archive ?
This section contained the largest concentration and variety of identifiable mineral grains; these included quartz, microcline and plagioclase feldspars, muscovite, and a large amount of kyanite (Fig.
Major minerals are quartz, plagioclase (albite-oligoclase), and perthitic microcline.
We found the K-feldspar in all six samples to be highly ordered, nearly maximum microcline.
Neither microcline nor albite showed ESR peaks for any grain size at any radiation level.
The composition of rocks and their metamorphic grade change rapidly from granulitic or high-grade amphibolitic in the PPZ to mainly medium-grade amphibolitic metasediments and intermediate to felsic metavolcanics, migmatites, and late-orogenic microcline granites in the Tallinn and Alutaguse zones.
On the other hand, microcline granites and migmatites are occasionally found in fault zones within the dominating granulite terrains of southern Estonia.
E) Identified using XRD, minerals listed in order of decreasing abundance: Hrb, hornblende; Plg, phlogopite; Aug, augite; Alb, albite; Ant, anorthite; Bi, biotite; Dio, diopside; Qz, quartz; Chl, chlorite; Mc, microcline.
Euhedral phenocrysts of variably ordered, vein-perthitic microcline contain 20-35 wt% exsolved albite component (Kirs & Utsal 1981).
The Sedgwick Granite is a grey, medium- to coarse-grained, equigranular, biotite granite that contains 35% microcline, 32% quartz, 28% oligoclase, 4% biotite, and trace amounts of zircon, apatite, and titanite.