Azurite is a rare blue carbonate of copper, found in many parts of the world in the upper oxidized portions of copper ore deposits as azurite is a product of oxidization of copper, along with malachite, a green basic carbonate hydroxide of copper that is far more abundant.
Azurite is a softer gemstone and is acid and humidity sensitive. It can occur in masses or crystals.
Azurite gets its blue color from copper and has been used as a pigment for over 4000 years. The Mesopotamians were big fans as well as the ancient Egyptians and Greeks.