TYROLITE

    Class : Phosphates, arsenates, vanadates
    Subclass : Hydrated arsenates
    Crystal system : Orthorhombic
    Chemistry : CaCu5(AsO4)2(CO3)(OH)4 6H2O
    Rarity : Uncommon to rare


Tyrolite is a fairly rare secondary arsenate from the oxidation zone of copper deposits. Some AsO4 groups are likely to be replaced by CO3 or SO4, which gives quite variable chemical compositions for this mineral. Its name comes from its region of discovery : Tyrol (Austria). Tyrolite generally occurs as sky blue to bluish green crystals, in the form of flattened laths or scales on {010} and elongated along [100] or [001]. The crystals are often grouped in radiate groups. Less commonly, tyrolite occurs as incrustations or as hummocky masses with a characteristic fibroradiated or micaceous texture. Tyrolite has a perfect micaceous cleavage according to {001}. It is an accessory ore of copper.

Main photo : Tyrolite from Mammoth Mine, Utah, USA © Rob Lavinsky

Tyrolite from Profunda Mine, Spain © Domenico Preite
Tyrolite & erythrite from Los Picayos Mine, Asturias, Spain © Manuel Echevarria Rodriguez
Tyrolite from Sankt Peter mine, Ste-Marie-aux-Mines, Haut-Rhin, France © Henk Smeets
Tyrolite from King Salomon Mine, Ste-Marie-aux-Mines, France © Thierry Brunsperger

Tyrolite in the World

The best crystals are thick tabular individuals that reach 2 cm, have been discovered in Penamerella (Asturias, Spain). Still in Spain, quality crystals are also known in Linares. Tyrolite exists in beautiful samples in the copper deposits of Utah (Gold Hill, Eureka, Mammoth) and Nevada (Majuba Hill). It was abundant and exploited as an accessory copper ore in Oued Mahisser (Tunisia), in Talmessi near Anarak (Iran) and in Jachymov (Czech Republic).

Tyrolite in France

In France, tyrolite is reported in several sites. It forms in particular rosettes of rectangular lamellae at the King Salomon mine (Haut-Rhin), in Chessy (Rhône), in the Aure valley (Hautes-Pyrénées), in Rabejac (Hérault), and millimetric kidney-shaped masses at La Treille (Ste-Marie-aux-Mines, Haut-Rhin).

Twinning

No twinning known for this mineral species.

Fakes and treatments

No fakes listed for this mineral species.



Hardness : 1.5 to 2
Density : 3 to 3.2
Fracture : Undetermined
Streak : Pale green


TP : Translucent to transparent
RI : 1.694 to 1.730
Birefringence : 0.036
Optical character : Biaxial -
Pleochroism : Low
Fluorescence : None


Solubility : Acids, ammonia

Magnetism : NoneRadioactivity : None