GUANAJUATITE

    Class : Sulfides and sulfosalts
    Subclass : Sulfides
    Crystal system : Orthorhombic
    Chemistry : Bi2Se3
    Rarity : Rare

Guanajuatite is a rare mineral, the selenite equivalent of bismuthinite and the dimorph of paraguanajuatite. It is a mineral from hydrothermal selenium deposits which is often found associated with clausthalite in gold-bearing veins. It owes its name to its discovery location : the Santa Catarina mine (Guanajuato, Mexico). Guanajuatite forms longitudinally striated acicular crystals of a maximum of 2 cm, as well as compact aggregates with a fibrous, foliated or grainy texture, of a dark bluish-gray color.

Main photo : Guanajuatite from Santa Catarina Mine, Guanajuato, Mexico © Eugene & Sharon Cisneros

Guanajuatite in the World

The most beautiful guanajuatite crystals come from the type locality : the Santa Catarina mine (Guanajuato, Mexico), they can measure up to 2 cm. It is also known in much less spectacular samples in the polymetallic veins of St-Andréasberg (Germany).

Guanajuatite in France

In France, guanajuatite is reported at the Salsigne gold mine.

Twinning

No twin known for this mineral species.

Fakes and treatments

No fakes recorded for this mineral species.


Hardness : 2.5 to 3
Density : 6.25 to 6.98
Fracture : Undeterminated
Streak : Gray

TP : Opaque
RI : -
Birefringence : -
Optical character : -
Pleochroism : None
Fluorescence : None

Solubility : Aqua regia

Magnetism : NoneRadioactivity : None