Tsumebite

Tsumebite


Composition: Pb2Cu(PO4)(SO4)(OH)
Crystal System : Monoclinic
Colours: Emerald-green
Lustre : Adamantine, vitreous
Hardness (H) : 3
Specific Gravity (S.G) : 6.13
Year of Discovery: 1912
IMA Number: 1912
IMA Status: Grandfathered
Discovered By: Karl Busz (German mineralogist)
Named for: The locality
References: Busz (1912)

Tsumeb is the Type Locality

Distribution

Extremely rare. First oxidation zone.

Occurrence

  • Supergene
  • 1st Oxidation Zone

Paragenetic and General Notes

Despite its early discovery, tsumebite from the type locality remains exceptionally rare and elusive.

Tsumebite was described as a new mineral from a suite of specimens sold by Dr F. Kranz, of Bonn, to the University of M√ľnster, in 1912. More or less simultaneously, but just a little too late, V.Rosicky, in Prague, described the same mineral on a specimen acquired from Wilhelm Maucher, and named it "Preslite" (Gebhard, 1999).

Tsumebite is typically well-crystallised, platy, always twinned, sometimes with multiple twinning and serrated re-entrants. Crystals are transparent, emerald-green or blue-green (not unlike dioptase).

The vast majority of specimens labelled as "tsumebite" in private collections are, in fact, arsentsumebite.

Tsumebite is reported to form pseudomorphs after the following minerals:  mimetite (rare, doubtful status); pyromorphite (rare, doubtful status).