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dioptase

[dahy-op-teys]
noun
  1. a mineral, hydrous copper silicate, CuSiO3⋅H2O, occurring in emerald-green crystals.

Origin of dioptase

1795–1805; < French, equivalent to di- di-3 + Greek optasía view
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for dioptase

dioptase

noun
  1. a green glassy mineral consisting of hydrated copper silicate in hexagonal crystalline form. Formula: Cu 6 Si 6 O 18 .6H 2 O

Word Origin for dioptase

C19: from French, from Greek dia- through + optos visible
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012