Current Names: Spanish: dioptas; Italian: dioptas Color: Green-Blue Colour Index: Not listed ASTM Lightfastness: Not tested Density: 3.3 Hardness: 5 Chemical Formula: CuSiO2(OH)2
Dioptase is a copper silicate mineral found in many parts of the world in the upper oxidized portions of copper ore deposits along with malachite. We buy our dioptase from copper mines in Altyn-tyube, 50 km east of Karaganda, Kirghiz Steppe, Kazakhstan. Dioptase is a bluer green than malachite and varies in masstone color from strong bluish green to vivid yellow green.
History of Use: Dioptase has been found as a pigment on ancient lime plaster statutes found in a Neolithic site in Jordan. In modern history, as a pigment dioptase has not been in wide spread use more than 10 years. It is a beautiful emerald green, and is especially good in mixtures. Dioptase can add brilliant highlights to glauconite. Use in its pure state where bright luscious colors are desired.
Grades: Available in three grades or fineness of grinds; fine, medium and coarse, which produce corresponding light, medium and dark tones of green when used in aqueous medium.
Permanence and Compatibility: It is stable in mixtures with other pigments, and its color is best appreciated when applied with other greens such as glauconite. No data has been published on the permanence and compatibility of dioptase.
Oil Absorption and Grinding: No data has been published on the oil absorption properties of dioptase. Grinding the mineral dioptase produces pigments that exhibits lighter and less saturated hues than coarser grades.
Toxicity: Dioptase is moderately toxic and care should be used in handling the dry powder pigment as well as the pigment dispersed in medium.
Read cautions about handling pigments