Walpurgite
9 in the gallery
Walpurgite is a uranyl bismuth arsenate mineral with a complex oxide-arsenate composition. It typically forms in small, often tabular or prismatic crystals that can appear black to brownish, with a dull to resinous lustre. The mineral’s crystal habit and high uranium content give it distinctive, dark appearances and a density that makes it stand out within parageneses dominated by uranyl minerals. Localities known for Walpurgite include German deposits where such bi-uranium-arsenate assemblages occur, sometimes associated with other uranyl oxides and arsenates.
- Formula
- (BiO)4(UO2)(AsO4)2 · 2H2O
- Rarity
- Rare
- Stability
- Stable
- Collector interest
- High Interest
- Classification notes
- Arsenate, uranyl arsenate hydrate; Strunz 8.EB
Key characteristics
- Crystal system
- orthorhombic
- Mohs hardness
- 3.5
- Specific gravity
- 6.7–6.8
- Luster
- adamantine, vitreous, greasy
- Transparency
- transparent, translucent
- Color
- yellow, orange, brown, green
- Streak
- yellow
- Fracture
- uneven
- Crystal habit
- tabular, prismatic, acicular, radiating, massive
- Radioactive
- Classic / historic
Where Walpurgite is found
Top localities
- Walpurgis Flacher vein3 specimens
- Weisser Hirsch mine, Schneeberg, Erzgebirgskreis3 specimens
- Neustädtel1 specimen
About Walpurgite
Collectors seek Walpurgite for its rarity and the rarity of uranyl bismuth arsenates in hand samples. The mineral’s unusual chemical formula and the interplay of heavy elements create a specimen that is memorable for its color, crystal form, and the story it tells about specialized ore environments. While not common in general collections, well-prepared crystals or well-documented tabular crystals can be prized by those pursuing uranyl-oxide chemistry and the broader arsenate family.