from The American Heritage® Dictionary of the English Language, 4th Edition

  • adj. Geology Having right-angled cleavage.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • adj. Having cleavage planes at right angles; as in orthoclase.

from the GNU version of the Collaborative International Dictionary of English

  • adj. Breaking in directions at right angles to each other; -- said of the monoclinic feldspars.

from The Century Dictionary and Cyclopedia

  • Characterized by cleavages at right angles to one another: said of certain species of the feldspar group, particularly orthoclase; pertaining to such species, or specifically to orthoclase.


ortho- +‎ Ancient Greek κλαστός (klastos, "broken") +‎ -ic (Wiktionary)



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