azurite

Azurite is a soft, deep blue copper carbonate mineral with the formula Cu3(CO3)2(OH)2. It forms through the weathering and oxidation of copper ore deposits and is noted for its intense azure color. It is commonly found in association with malachite, chrysocolla, and other secondary copper minerals.

Crystals are usually monoclinic and may occur as prismatic crystals, crusts, or massive nodules. The mineral typically ranges from blue to blue-green in color, with a vitreous to dull luster. Its hardness on the Mohs scale is about 3.5 to 4.

Geology and occurrences: Azurite forms in the oxidized zones of copper deposits worldwide, including parts of the United States, Mexico, the Democratic Republic of the Congo, Namibia, and Australia. It forms by the dissolution of copper ions and carbonate, and can alter to malachite in surface weathering.

Uses and significance: Azurite has been used as a pigment since antiquity, especially in the Mediterranean and Middle East, and in medieval and Renaissance art. It can decompose to malachite upon light exposure and air, causing color changes; it is now often replaced in paintings by synthetic pigments.

Etymology and properties: the name azurite derives from the French azur, azure. The mineral is relatively soft and unstable as a pigment. When heated, azurite decomposes to copper oxide, releasing carbon dioxide and water.

In computing, Azurite is also the name of an open-source storage emulator for Microsoft Azure Storage, allowing developers to test blob, queue, and table services locally.