Composition: Fe2+2Ge4+O4
Crystal System : Cubic
Colours: Grey-black
Lustre : Sub-metallic
Hardness (H) : 5
Specific Gravity (S.G) : 5.51
Year of Discovery: 1972
IMA Number: 1972-004
IMA Status: Redefined
Discovered By: Bruno H. Geier (Tsumeb mineralogist)
Named for: Discoverer

 Tsumeb is the Type Locality


Extremely rare. Type specimen is from 29 Level, second oxidation zone.


  • Supergene
  • 2nd Oxidation Zone

Paragenetic and General Notes

Brunogeierite has a spinel-type structure. The formula has been restated as (Fe2+)2Ge4+O4 (Cempirek and Groat, 2013) and this has been approved by the IMA. Cubic crystals, exceptionally to 5 mm (but usually sub-mm), grey-black, encrusting cavities in tennantite. Brunogeierite is magnetic and, visually, it resembles magnetite.