Ianbruceite, [Zn2(OH)(H2O)(AsO4)](H2O)2, is a hydrated zinc arsenate that forms during the oxidation of base-metal sulfide minerals; it crystallizes with monoclinic symmetry. The type locality is the Tsumeb mine, in the Otjikoto region of northern Namibia, where it was found on 44 level, some 1,500 meters below the surface in the so-called third oxidation zone (Cooper et al. 2012). The type material consists of flattened aggregates of thin, platy, pale blue to sky-blue crystals to 80 μm long, forming flattened and ellipsoidal aggregates to 0.5 mm across, associated with leiteite, köttigite, legrandite, and adamite. It is named for Ian Robert Bruce, a mineral dealer from Somerset, England, who was instrumental in the re-opening of the Tsumeb mine for specimen recovery in the late 1990s. Ianbruceite has subsequently been reported from the Driggeth mine in the Caldbeck Fells, Cumbria, England (Neall et al. 2013).
Dr. Malcolm Southwood has collected minerals for more than thirty-five years and is a mineralogist by training. His special interests are the minerals of southern Africa and southwest England.