Word Study
orthoclase
CIDE DICTIONARY
orthoclase, n. [Ortho- + Gr. to break.].
Common or potash feldspar crystallizing in the monoclinic system and having two cleavages at right angles to each other. See Feldspar. [1913 Webster]
OXFORD DICTIONARY
orthoclase, n. a common alkali feldspar usu. occurring as variously coloured crystals, used in ceramics and glass-making.
Etymology
ORTHO- +Gk klasis breaking
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