Definition of orthoclase in English:


Syllabification: or·tho·clase
Pronunciation: /ˈôrTHəˌklās, -ˌklāz


  • A common rock-forming mineral occurring typically as white or pink crystals. It is a potassium-rich alkali feldspar and is used in ceramics and glassmaking.
    More example sentences
    • Feldspars are added as orthoclase in order to reduce the devitrification of the glass.
    • Of these, alkali feldspar, particularly orthoclase, is the most common.
    • Associated minerals are white orthoclase, milky quartz, and muscovite.


mid 19th century: from ortho- 'straight' + Greek klasis 'breaking' (because of the characteristic two cleavages at right angles).

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Pronunciation: ˌkɒlərəˈtjʊərə
elaborate ornamentation of a vocal melody