orthoclase

American  

[awr-thuh-kleys, -kleyz] / ˈɔr θəˌkleɪs, -ˌkleɪz /

noun

1. a common white or pink mineral of the feldspar group, KAlSi 3 O 8 , having two good cleavages at right angles, and found in silica-rich igneous rocks: used in the manufacture of porcelain.

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orthoclase British  

/ ˈɔːθəʊˌkleɪs, -ˌkleɪz /

noun

1. a white to pale yellow, red, or green mineral of the feldspar group, found in igneous, sedimentary, and metamorphic rocks. It is used in the manufacture of glass and ceramics. Composition: potassium aluminium silicate. Formula: KAlSi 3 O 8 . Crystal structure: monoclinic

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orthoclase Scientific  

/ ôr′thə-klās′ /

1. A white to yellowish red monoclinic mineral of the potassium feldspar group that forms from medium- to low-temperature magmas. Chemical formula: KAlSi ₃ O ₈ .

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Etymology

Origin of orthoclase

1840–50; ortho- + -clase < Greek klásis cleavage, breaking

Example Sentences

See Examples For:

orthoclase

Felsic is the compositional term applied to continental igneous minerals and rocks that contain an abundance of orthoclase feldspar.

From Textbooks ● Jan. 1, 2017

Granite is a mixture of quartz, felspar, and mica in variable proportions, and the quality of the soil it yields depends on whether the variety of felspar present be orthoclase or albite.

From Elements of Agricultural Chemistry by Anderson, Thomas

It often occurs as a constituent of granite, not unfrequently being associated in the same rock with pink felspar or orthoclase.

From Geology by Geikie, James

These larger felspars have no crystalline outlines and consist of orthoclase or microcline surrounded by borders of white oligoclase.

From Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 3 "Gordon, Lord George" to "Grasses" by Various

At the same time orthoclase and microcline are both potassium felspars; yet the former crystallizes in the monoclinic, and the latter in the triclinic system.

From The New Gresham Encyclopedia Volume 4, Part 3: Estremoz to Felspar by Various