Malachite-Azurite rough pieces from Morenci, Arzona/USA.

The mineral azurite is a copper carbonate with the chemical formula Cu3(CO3)2(OH)2. The transparent to translucent typically azure blue azurite has a light blue stripe color, a glassy luster and the crystal system is monoclinic. The average density is 3.83 and the hardness is 3.5 to 4. Azurite is not radioactive and is bright blue to dark purple pleochroic. The name azurite is derived from the Persian lazhward, meaning "blue". The very common azurite occurs mainly in the oxidized parts of copper deposits or as a secondary mineral in carbonate-rich waters. It is also formed when copper-bearing solutions react with limestone. The type locality of azurite is Chessy-les-Mines, Rhône-Alpes, France. Azurite has been used for centuries as a blue pigment. It was formerly known as Azurro Della Magna (from Italian). When mixed with oil it becomes slightly green. When mixed with egg yolk it becomes gray-green. Azurite is often used in jewelry and is a popular mineral among collectors. Malachite is a mineral used as a gemstone. It is a copper carbonate with the chemical formula Cu2CO3(OH)2. It is often found in nature together with the related azurite (Cu3(CO3)2(OH)2). The crystal structure is monoclinic and is usually botryoidal in shape. The name of the mineral comes from the Greek and refers to the color of the mallow (cheese herb). Malachite was worked as a gemstone at an early stage. In Egypt cameos, amulets and ornamental objects were made from it. The Greeks and Romans also knew malachite. The pulverized mineral was used as make-up and as a dye for paint. It was claimed that malachite was able to protect children against sorcery and witchcraft. In ancient times it was thought that it could cure eye ailments. In the 16th century it was used in Central Europe to promote the growth of children and to relieve pain. Malachite is found worldwide. In Asia, significant quantities are found in China, India and the Uralin Russia, as well as in Australia. On the American continent, the most important reserves are in the southwestern United States, mainly in the state of Arizona (a block of 4.5 tons was found near Bisbee). Malachites in Mexico, Chile and Cuba are of gemstone quality. However, the most important and historically best-known malachite reserves are in Africa. Here, malachite has been mined since ancient times in the Copperbelt in Congo-Kinshasa and Zambia. The malachite zone extends from the province of Katanga (Congo-Kinshasa) to Zambia. These malachites are considered the most beautiful and best in the world. Beautiful malachite crystals are found in Namibia (Tsumeb), Morocco, Zimbabwe and Angola. Europe has only small deposits of little significance in Germany, Slovakia, Hungary, Romania, England and France. In Belgium, malachite is found in the Salm valley and in limestone at Visé. Malachite is formed in oxidation zones of copper deposits.