Liroconite

Liroconite Wheal Gorland, Cornwall, England Thumbnail, 2.3 x 1.9 x 1.0 cm © irocks.com

Chemical Formula: Cu2Al(AsO4)(OH)4·4H2O
Locality: Wheal Gorland, Gwennap, Cornwall, England, UK
Name Origin: From the Greek, liros – “pale” and konia – “powder.”

Liroconite is a complex mineral: Hydrated copper aluminium arsenate hydroxide, with the formula Cu2Al(AsO4)(OH)4·4H2O. It is a vitreous monoclinic mineral, colored bright blue to green, often associated with malachite, azurite, olivenite, and clinoclase. It is quite soft, with a Mohs hardness of 2 – 2.5, and has a specific gravity of 2.9 – 3.0.

It was first identified in 1825 in the tin and copper mines of Devon and Cornwall, England. Although it remains quite rare it has subsequently been identified in a variety of locations including France, Germany, Australia, New Jersey and California.

The type locality for Liroconite is Wheal Gorland in St Day, Cornwall in the United Kingdom.

It occurs as a secondary mineral in copper deposits in association with olivenite, chalcophyllite, clinoclase, cornwallite, strashimirite, malachite, cuprite and limonite.

History

Discovery date : 1825
Town of Origin: REDRUTH ET ST. DAY, CORNOUAILLES
Country of Origin : ANGLETERRE

Optical properties

Optical and misc. Properties: Transparent to Translucent
Refractive Index: from 1,61 to 1,67 / de 1,61 à 1,67
Axial angle 2V : ~72°

Physical Properties

Cleavage: {100} Indistinct, {011} Indistinct
Color:     Light blue, Green, Sky blue, Verdigris green.
Density: 2.9 – 3, Average = 2.95
Diaphaneity: Transparent to Translucent
Fracture: Sub Conchoidal – Fractures developed in brittle materials characterized by semi-curving surfaces.
Hardness: 2-2.5 – Gypsum-Finger Nail
Luminescence: Non-fluorescent.
Luster: Vitreous – Resinous
Streak: light blue

Photos:

Liroconite Wheal Gorland, St Day United Mines, Gwennap area, Cornwall, England ( TYPE LOCALITY ) Miniature, 4.4 x 4.2 x 3.0 cm © irocks
Liroconite Wheal Gorland, Cornwall, England, UK Small Cabinet, 7 x 4.5 x 4.5 cm © irocks
Wheal Gorland, St Day United Mines (Poldice Mines), Gwennap, Camborne – Redruth – St Day District, Cornwall, England, UK © François Périnet
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