WALPURGITE

    Class : Phosphates, arsenates, vanadates
    Subclass : Hydrated arsenates
    Crystal system : Triclinic
    Chemistry : Bi4(UO2)O4(AsO4)2 2H2O
    Rarity : Rare

Walpurgite is a rare secondary mineral from the oxidation zone of hydrothermal deposits containing bismuth, uranium and arsenic. It owes its name to its discovery location : the Walpurgis vein of the Weisser Hirsch mine (Germany). Walpurgite forms elongated lamellar crystals, grouped in radiate bundles or in subparallel aggregates not exceeding 6 mm, of a wax yellow to straw yellow color, sometimes colorless.

Main photo : Walpurgite from Schmiedestollen dump, Wittichen, Germany © Uwe Haubenreisser

Walpurgite from Clara Mine, Germany © Michael Förch
Walpurgite from Weisser Hirsch Mine, Neustädtel, Schneeberg, Germany © Stephan Wolfsried
Walpurgite from Schmiedestollen, Wittichen, Germany © Michael Förch
Walpurgite from Schmiedestollen, Wittichen, Germany © Gianfranco Ciccolini

Walpurgite in the World

Walpurgite is a rare mineral known mainly in the polymetallic uranium veins of Germany, in Saxony (Schneeberg) and in the Black Forest (Wittichen, Tribach...). It is also listed in Jachymov (Czech Republic) and near Dalbeattie in Scotland.

Walpurgite in France

Walpurgite is not present in the French underground.

Twinning

Twinning is known on {010}, forming pseudo-monoclinic aggregates resembling gypsum.

Fakes and treatments

No fakes listed for this mineral species.


Hardness : 3.5
Density : 6.59
Fracture : Undetermined
Streak : Brown-yellow

TP : Translucent to transparent
RI : 1.871 to 2.050
Birefringence : 0.134 to 0.150
Optical character : Biaxial -
Pleochroism : Low
Fluorescence : None

Solubility : -

Magnetism : NoneRadioactivity : Medium