Composition: Zn2O[As2O3(OH)] (H2O)3.53
Crystal System : Monoclinic
Colours: Very pale-blue, sky-blue
Lustre : Vitreous
Hardness (H) : 1
Specific Gravity (S.G) : 3.197
IMA Number: 2011-049
IMA Status: Approved
Discovered By: Georg Gebhard (German collector)
Named for: Ian Bruce (British dealer)
References: Cooper et al. (2012)

Tsumeb is the Type Locality


Extremely rare. Third oxidation zone, Level 44.


  • Supergene
  • 3rd Oxidation Zone

Notable Finds

The type specimen is from the third oxidation zone, on Level 44, the so-called "Zinc Pocket".

Paragenetic and General Notes

The type specimen was obtained by Georg Gebhard in 1994, and is figured in Gebhard (1999, p.296); this (then-uncharacterised) mineral was designated GS17 by Gebhard.

Occurs with leiteite, köttigite, legrandite and adamite. Recent studies initiated by William (Bill) Pinch indicate that the dark blue "köttigite" associated with ianbruceite may, in fact, be blue legrandite (Bill Pinch, personal communication to M.Southwood, 2015). Ianbruceite, köttigite, and legrandite all share very similar chemistry as hydrated zinc arsenates.