DIOPTASE (miniature, large crystal)

Dioptase is a striking mineral characterized by its vibrant emerald-green to bluish-green hue, classified as a cyclosilicate of copper. It exhibits a range of transparency from transparent to translucent and possesses a vitreous to sub-adamantine luster. The chemical composition of dioptase is Cu6Si6O18·6H2O, with an alternative representation as CuSiO2(OH)2. It has a Mohs hardness of 5, comparable to that of tooth enamel, and a specific gravity ranging from 3.28 to 3.35. The mineral features two perfect cleavage directions and one very good cleavage direction, but it is notably fragile, necessitating careful handling. Dioptase crystallizes in a trigonal system, typically forming six-sided crystals that culminate in rhombohedral shapes.

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