Azurite is a soft, deep blue copper mineral produced by weathering of copper ore deposits. This mineral carbonate has been known since ancient times. From the Greek name kuanos (κυανός: "deep blue,") and the Latin name caeruleum. The blue of azurite is exceptionally deep and clear
Azurite is one of the two basic copper(II) carbonate minerals, the other being bright green malachite. Simple copper carbonate (CuCO3) is not known to exist in nature. Azurite has the formula Cu3(CO3)2(OH)2, with the copper(II) cations linked to two different anions, carbonate and hydroxide.
Azurite crystals are monoclinic, and when large enough to be seen they appear as dark blue prismatic crystals.