azurit

Azurit, also spelled azurite, is a copper carbonate hydroxide mineral with the chemical formula Cu3(CO3)2(OH)2. It is a secondary mineral that forms in the oxidation zones of copper ore deposits, often occurring with malachite. Azurit frequently appears as deep blue masses, nodules, or crusts, and crystals are relatively rare.

In terms of properties, azurit has a Mohs hardness of 3.5 to 4 and a vitreous to dull luster. Its streak is light blue, and the specific gravity ranges around 3.7 to 3.9. The characteristic color is a rich azure to blue, which can influence by association with secondary carbonate minerals. Azurit is moderately soft and can be weathered to malachite over time, especially under exposure to air and moisture.

Formation and occurrence: as a secondary copper mineral, azurit forms when copper sulfide minerals are oxidized. It is commonly found in the same deposits as malachite and can occur worldwide in copper-bearing regions, with notable localities in the Americas, Africa, Europe, and Asia.

Uses and stability: historically, azurit was used as a blue pigment in paintings and outlined in various artistic traditions, though it is less common today due to its instability under light and heat and its tendency to alter to malachite and other species. It is not a primary ore of copper in modern mining, where malachite and other copper carbonates are more economically significant. Etymology traces the name to the blue pigment association, derived from European languages.