Composition: (Sb,As)2MoO6
Crystal System : Monoclinic
Colours: White
Lustre : Silky
Hardness (H) : 1.0-1.5
Year of Discovery: 1999
IMA Number: 1999-019a
IMA Status: Approved
Named for: Friederich Karl Biehl (German Mineralogist)

Tsumeb is the Type Locality


Very rare. Probably third oxidation zone only.


  • Supergene
  • 3rd Oxidation Zone

Notable Finds

The type specimen is believed to originate from somewhere between 42 Level and 48 Level (Von Bezing, 2007).

Paragenetic and General Notes

Notable for its essential antimony content (rare at Tsumeb). White fibres to 10mm, but only a few µm in diameter, as felty aggregates. Translucent, with a silky lustre. Soft and flexible. Typically associated with anglesite.