KRENNERITE

    Class : Sulfides and sulfosalts
    Subclass : Tellurides
    Crystal system : Orthorhombic
    Chemistry : Au3AgTe8
    Rarity : Rare to very rare

Krennerite is a rare hydrothermal mineral from gold-bearing epithermal veins where it accompanies native gold and other tellurides (petzite, sylvanite, hessite). It is one of the rarest tellurides. It was named in honor of the Hungarian mineralogist Joseph A. Krenner who was responsible for the first description of the mineral. The krennerite crystals form stubby prisms ridged parallel to [001]. It is a mineral with an intense metallic luster, silver-white in color, tarnishing to a pale brass yellow. It decomposes under surface conditions, releasing films of native gold. Its silver content can exceed 5%. It is a very incidental gold ore.

Main photo : 3.6 cm krennerite from Emperor Mine, Fidji Islands © Rock Currier

Krennerite in the World

The best known crystals of krennerite exceed 3 cm, they come from the gold mines of Colorado (Cripple Creek), Romania (Sacarimb) and the Fiji Islands (Emperor mine). In 1914, in the Cresson gold mine (Colorado) a cavity measuring 12 m x 6 m x 5 m was discovered entirely lined with crystals of calaverite (up to 1.5 cm), sylvanite, krennerite and gold. but unfortunately few samples of this marvel were preserved...

Photo de droite : Krennerite from Ajax Mine, Colorado, USA © Marko Burkhardt

Krennerite in France

Krennerite is not known in the French underground.

Twinning

No twins known for this mineral species.

Fakes and treatments

No fakes recorded for this mineral species.


Hardness : 2 to 3
Density : 8.62
Fracture : Irregular to sub-conchoidal
Streak : Silver white

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

Solubility : -

Magnetism : NoneRadioactivity : None