Azurite

Azurite is definitely an azure-blue copper mineral, occasionally found as prismatic crystals (rarely faceted), but more usually in massive form Intergrown with malachite.
Found specifically in copper-mining areas for example Australia, Chile, the first kind USSR, Africa, and China. Stones from Chessy, near lyons in France are known as chessylite.





 

Properties

Chemical Composition: Copper Carbonate (unstable state) - Cu₃(CO₃)₂(OH)₂

Classification / Type: The unstable state alters to malachite and is generally found in combination as azumalachite.

Colors / Varieties: Violet blue commonly associated with malachite; azurite with large percentage of malachite is called azurmalachite. Transparency: Transparent (rare) to Opaque.

Crystal System / Forms: Monoclinic System / Prismatic crystals, botryoidal, stalagmatic, massive, banded.

Hardness: 3.5 - 4

Specific Gravity: 3.70 - 3.90

Cleavage / Fracture: Perfect prismatic cleavage observed as schiller but not seen in aggregate / Conchoidal fracture.

Optic Character: Anisotropic, D.R.; Biaxial positive

Lustre: Vitreous to waxy

Refractive Index / Birefringence: 1.730 - 1.840 / 0.110

Pleochroism: Distinct shades of blue (in single crystal)

Dispersion: -

Magnification: Surface texture

U.V. Fluorescence: Inert

Spectrum: Not characteristic

Cause of Color: Copper

Treatment (Enhancement): -

Specific Tests & Remarks: Attacked by hydrochloric acid, light blue streak

Synthesis: -

Simulants (with key separation tests): Azurmalachite (structure), Lapis Lazuli (structure, R.I., S.G.), Chrysocolla (structure, R.I., S.G.)

Geological Occurrence: As a secondary mineral in copper deposits. Alters to malachite and formed in association with malachite.

Sources: U.S.A. (Arizona), Namibia, France, Romania, Australia, Siberia.

Cuts & Uses: Cabochons, beads, carvings.