Azurite ground as a pigment
Azurite (also known as Chessylite) is a carbonate mineral with chemical composition Cu3(CO3)2(OH)2, (copper carbonate hydroxide). Azurite crystallizes in the monoclinic system with light to dark blue prismatic crystal form, although the mineral is more commonly massive to nodular to stalactitic in form. It has a Mohs hardness of 3.5 to 4 and a specific gravity of 3.77 to 3.89. Azurite is often found in association with the green mineral malachite as a result of the weathering and oxidation of copper sulfide minerals. Azurite is often pseudonorphically replace by malachite as the latter is the more oxidized form.
The name azurite comes from the Arabic word for blue. Azurite is used in jewelry and also collected as a beautiful mineral specimen.
Use as a pigment
Azurite has been used as a blue mineral pigment for centuries. It was formerly known as Azurro Della Magna (from Italian). When mixed with oil it turns slightly green. When mixed with egg yolk it turns green-grey. It is also known by the names Blue Bice and Blue Verditer. Older examples of azurite pigment may show a more greenish tint due to oxidation to malachite.
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