orthoclase

[ awr-thuh-kleys, -kleyz ]

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.

orthoclase

/ 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

orthoclase

/ 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 .

Word History and Origins

Origin of orthoclase¹

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

Example Sentences

There is also some variation in the amount of quartz present, and in the relative importance of the orthoclase and plagioclase.

From Project Gutenberg

Orthoclase becomes a clear glass filled with bubbles: at a lower temperature beryl behaves in the same way.

From Project Gutenberg

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

From Project Gutenberg

Sanidine, san′i-din, n. a clear glassy variety of orthoclase.

From Project Gutenberg

Vogesites contain hornblende and orthoclase; spessartites, hornblende and plagioclase.

From Project Gutenberg