Azurite is a naturally occurring copper carbonate hydroxide mineral with the chemical formula Cu₃(CO₃)₂(OH)₂. It belongs to the carbonate mineral group and crystallizes in the monoclinic crystal system. Azurite is widely recognized for its rich, deep blue color, which has made it popular throughout history as a pigment and ornamental stone. The intense blue color of Azurite is caused by the presence of copper in its structure. It typically appears in shades ranging from bright azure blue to dark navy blue. The mineral can be found in both crystalline and massive forms, with crystals often displaying a vitreous to silky luster. Transparent crystals are rare, while most Azurite is opaque to translucent.