Dioptase Crystals & Specimens

Dioptase is a lustrous emerald-green copper-based mineral mostly found in arid regions where it forms as a secondary mineral in copper deposit oxidation zones. This mineral commonly appears as small rhombohedral crystals, typically less than a few millimeters in size. It is quite popular with mineral collectors due to its vibrant emerald green color and gemmy qualities.

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What Is Dioptase?

Dioptase is a secondary mineral of copper sulfide that most commonly forms as fragile, doubly terminated hexagonal crystals. This very distinct mineral will form in tightly packed clusters of very small crystals. A crystal over 1 centimeter in length is very rare and only found in a few localities. Although typically rhombohedral, crystals can take druzy, radiating, botryoidal, or grainy forms. The name is derived from Greek, and roughly translates to “to see through.” This refers to its translucent nature and the ability to see its cleavage planes within the crystal. The largest, highest quality crystals are often cut into gems, though they are rather fragile. Despite this, dioptase is very valuable due to its visual appeal and mimicry of emerald gemstones. Its color and shape has lent it the nicknames “Emerald Copper” and “Emerald Malachite.”

How Does Dioptase Form?

Dioptase requires very specific conditions to form and is therefore fairly uncommon. Because of the high acidity necessary for oxidation to occur, silica often won’t form unless in highly alkaline conditions. However, due to prolonged exposure to dry climates and the correct amount of carbonate as a buffer, silica will react with copper to form dioptase or chrysocolla.

Where Is Dioptase Found?

Anywhere there is a large-scale copper mine in a dry area, dioptase is sure to be present somehow! Cream-of-the-crop dioptase comes from Tsumeb, Namibia, where the largest stand-alone crystals are found. Namibia also produces some of the finest dioptase-malachite and dioptase-shattuckite associations. The first high grade dioptase was extracted from Kazakhstan, but Namibia has easily superseded that location in both size and quality of crystals with recent finds. The Congo and Argentina also produce a lot of dioptase, though not in the same exceptional quality as other mines. Arizona is the only state in the U.S. known to produce dioptase, but not gem-quality specimens. These mines only produce druzy and encrusting varieties of dioptase.

Common Associations

As one might expect, dioptase is found in association with other copper and silicate-based minerals. The most common include chrysocolla, malachite, calcite, and quartz. Shattuckite is a known pseudomorph of dioptase, typically found in Arizona, Congo, and Namibia.

Featured Photos

Large Emerald-Green Dioptase Crystals - Congo #343354

Gemmy Dioptase Crystal Cluster - N'tola Mine, Congo #175945

DIOPTASE CRYSTALS & SPECIMENS

What Is Dioptase?

How Does Dioptase Form?

Where Is Dioptase Found?

Common Associations

Featured Photos