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Azurite Mineral Facts:

Chemical Formula: Cu₃(CO₃)₂(OH)₂  The Mineral is 55.3% Copper by weight.

Colors: The mineral is an intense dark blue, and can be translucent or transparent, or earthy and opaque. It is pleochroic in shades of blue.  The mineral is named for its blue color.

Hardness: 3.5 to 4
Hardness varies somewhat depending on formation and impurities.

Density: 3.8

Cleavage: {001} perfect,  {100} fair  

Crystallography: Monoclinic
The crystals are tabular, prismatic, or wedge-shaped monoclinic forms. Some crystals are complex and distorted in development, sometimes in radiating spherical groups with a radiating botryoidal structure.

Luster:. Vitreous

Optics: (Refractive Index):  a = 1.730; b = 1.758; y = 1.838

Composition, Structure and Associated Minerals:
Azurite occurs also as veins and incrustations and in massive, radiated, and earthy forms associated with malachite and other copper compounds. Its most frequent associate is malachite, into which it readily alters. Azurite is more often found in crystals than is malachite. Psudomorphs after cuprite are uncommon, but exist.

Identification and Diagnostics
Azurite is characterized chiefly by its azure-blue color. It is fusible (3), giving a green flame. With fluxes in Reducing flame on charcoal gives copper globule. Soluble in hydrochloric acid with effervescence of carbon dioxide. Solution turns deep blue with excess of ammonia. It gives much water when heated in a closed tube. It is soluble in nitric acid.

Occurrence, Localities and Origins:
The mineral occurs in the oxidized zone of copper veins and related deposits. It is an intermediate product in the change of other copper compounds to malachite. The origin and associations same as for malachite. Widely distributed with copper ores, but not so common as malachite. Azurite occurs in beautiful crystals at Cressy, France; near Redruth, in Cornwall, England; at Phoenixville, Pennsylvania; at Mineral Point, Wisconson; at the Copper Queen Mine, Bisbee, Arizona; at the Mammoth Mine, Tintic district, Utah and at Hughes's Mine, in California, and at many other copper mines in this country and abroad.

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Druzy Azurite, with minor green malachite.

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