Formula: Bi4O4(UO2)(AsO4)2.2H2O
Hydrated normal arsenate, bismuth and uranium mineral
Specific gravity: 6.69
Hardness: 3½
Streak: Yellow-white
Colour: Yellow, orange-yellow; colourless to light yellow in transmitted light.

Hydrothermal environments

Walpurgite is a rare secondary mineral in the oxidised zone of bismuth-uranium-arsenic-bearing hydrothermal mineral deposits.

At the type locality, the Weißer Hirsch Mine, Neustädtel, Saxony, Germany, walpurgite is associated with trögerite, zeunerite, uranosphaerite, uranospinite and torbernite. At Joachimsthal, Bohemia, Czech Republic, walpurgite is associated with torbernite.

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