Azurite

Azurite “Flower”
Azurite “Flower”

Formula: Cu3(CO3)2(OH)2
Colour: Azure blue, blue, light blue, or dark blue; light blue in transmitted light
Lustre: Vitreous
Hardness: 3½ – 4
Specific Gravity: 3.77
Crystal System: Monoclinic
Name: From the ancient Persian lazhward, meaning “blue”, in allusion to the color. Name changed to azurite in 1824 by Francois Sulpice Beudant.
Type Locality: Chessy copper mines, Chessy-les-Mines, Villefranche, Rhône, Auvergne-Rhône-Alpes, France

Azurite is a soft, deep blue copper mineral produced by weathering of copper ore deposits. It is also known as Chessylite after the type locality at Chessy-les-Mines near Lyon, France.

The mineral, a carbonate, has been known since ancient times, and was mentioned in Pliny the Elder’s Natural History under the Greek name kuanos (κυανός: “deep blue,” root of English cyan) and the Latin name caeruleum. The blue of azurite is exceptionally deep and clear, and for that reason the mineral has tended to be associated since antiquity with the deep blue color of low-humidity desert and winter skies.

Physical Properties of Azurite

Cleavage: {011} Perfect, {100} Fair
Color: Azure blue, Blue, Light blue, Dark blue.
Density: 3.77 – 3.89, Average = 3.83
Diaphaneity: Transparent to subtranslucent
Fracture: Brittle – Conchoidal – Very brittle fracture producing small, conchoidal fragments.
Habit: Prismatic – Crystals Shaped like Slender Prisms (e.g. tourmaline).
Habit: Stalactitic – Shaped like pendant columns as stalactites or stalagmites (e.g. calcite).
Habit: Tabular – Form dimensions are thin in one direction.
Hardness: 3.5-4 – Copper Penny-Fluorite
Luminescence: Non-fluorescent.
Luster: Vitreous (Glassy)
Streak: light blue

Photos

Azurite, columnar aggregate of stalactites, Bisbee Arizona. Detail, size 13 x 75 x 15 cm. Part of the Rocks and Minerals display in the Royal Ontario Museum Toronto
Azurite, columnar aggregate of stalactites, Bisbee Arizona. Detail, size 13 x 75 x 15 cm. Part of the Rocks and Minerals display in the Royal Ontario Museum Toronto
Azurite in siltstone, Malbunka mine, NT
Azurite in siltstone, Malbunka mine, NT
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