ANTLERITE

    Class : Sulphates, chromates, molybdates
    Subclass : Anhydrous sulfates
    Crystal System : Orthorhombic
    Chemistry : Cu3SO4(OH)4
    Rarity : Rare

Antlerite is a secondary sulphate present in the oxidation zones of copper deposits in a desert climate. It takes its name from its place of discovery : the Antler mine (Arizona). It occurs as stocky, often thick tabular crystals, as friable aggregates of needle-like to fibrous crystals, or as banded fibrous masses. Its emerald green to blackish green color is more reminiscent of brochantite or atacamite than malachite, although confusion is possible and probably common. It is a mineral that forms rapidly, often on a base of sulphides, but disappears just as quickly by transformation into brochantite, which is more stable. Despite this ephemeral character, antlerite provided an essential part of the copper ore in the great Chilean mine of Chuquicamata, the largest copper mine in the world.

Main photo : Antlerite from Blanchard Mine, New Mexico, USA © Ray Demark

Antlerite from Chuquicamata Mine, Chile © Christian Rewitzer
Antlerite from Chuquicamata Mine, Chile © Stephan Wolfsried
Antlerite from Algorta Mine, Chile © Germano Fretti
Antlerite from Blanchard Mine, New-Mexico, USA © Douglas Merson

Antlerite in the World

Beautiful crystallizations of antlerite come from mines in Arizona (Antler mine at Kingman, Bisbee), Nevada and Sierre Mojada (Mexico).


Antlerite in France

In France, antlerite is found in neoformation in the slag of the Crozet mine (Loire).

Photo on the right : Crozet antlerite, Loire, France © Yannick Vessely

Twinning

No known twins for this mineral species.

Fakes and treatments

No fake recorded for this mineral species, but often confused with brochantite, atacamite or malachite.



Hardness :  3.5
Density : 3.88
Fracture : Conchoidal
Trace : Pale green




TP : Translucent to transparent
RI : 1.726 to 1.789
Birefringence : 0.063
Optical character : Biaxial +
Pleochroism : Visible
Fluorescence : None


Solubility : Sulfuric acid

Magnetism : None
Radioactivity : None