The mineral azurite is a copper-carbonate having the chemical formula Cu3 (CO3) 2 (OH) 2. The transparent to translucent azure azurite typically has a light blue stripe color, gloss glass and crystal system is monoclinic. The average density is 3.83 and the hardness is 3.5 to 4 Azurite is not radioactive and light blue to dark purple pleochroïsch. The name azurite is derived from the Persian lazhward that "blue" means. The very general azurite occurs mainly in the oxidized portions of copper deposits or as a secondary mineral in carbonate-rich water. It is also formed when copper-containing solutions react with limestone. The type of location is azurite Chessy-les-Mines, Rhône-Alpes, France. Azurite has been used for centuries as a blue pigment. It was formerly known as Azurro Della Magna (in Italian). When mixed with oil, the lightly green. When mixed with egg yolk, it is gray green. Azurite is often used in jewelry and is a popular mineral for collectors.