dioptase Min.
(daɪˈɒpteɪs)
[a. F. dioptase (Haüy 1801), irreg. f. Gr. δι-, δια- through + ὀπτός seen, visible: cf. διόπτης a looker through.]
A translucent silicate of copper, crystallizing in six-sided prisms, called emerald copper ore.
| 1804 W. Nicholson tr. Fourcroy's Chem. II. 430 Dioptase is an ore of copper. 1868 Dana Min. 402 Dioptase occurs disposed in well defined crystals and amorphous on quartz. |