Schultenite

Schultenite


Composition: PbHAsO4
Crystal System : Monoclinic
Colours: Colourless
Lustre : Sub-adamantine
Hardness (H) : 2.5
Specific Gravity (S.G) : 6.07
Year of Discovery: 1925
IMA Number: 1926
IMA Status: Grandfathered
Discovered By: L.J. Spencer (British mineralogist)
Named for: Baron August de Schulten (French mineralogist)

Tsumeb is the Type Locality

Distribution

Very rare. First oxidation zone. Second oxidation zone.

Occurrence

  • Supergene
  • 1st Oxidation Zone
  • 2nd Oxidation Zone

Notable Finds

The type specimen is from 7 Level, in the first oxidation zone. In the second oxidation zone, a schultenite pocket was found on 28 Level during 1975, with crystals mainly < 10 mm but exceptionally to 40 mm, and associated with cuprian adamite and keyite. In early 1980, the largest recorded schultenite crystal - 175 mm in length - was recovered from the north-east stope on 35 Level (Keller and Bartelke, 1982). (Note that Von Bezing et al. (2014) suggest that this large crystal also came from the 28 Level discovery.)

Paragenetic and General Notes

Schultenite occurs as flattened, colourless, transparent, bladed crystals, commonly with a rhombic cross-section, and often resembling gypsum.

The type specimen for schultenite was sold to the Natural History Museum, London, labelled as "lanarkite", by German dealer Wilhelm Maucher in 1925; the type assemblage includes schultenite with azurite, anglesite, bayldonite and mimetite.  Recent analysis of a pale, spearmint-green partial coating on the type specimen has shown that thometzekite is also part of this type assemblage (Mike Rumsey, personal communication to M. Southwood, October 2015).  This appears to be the first confirmed observation of thometzekite from the first oxidation zone.

The largest recorded schultenite crystal, 175 mm, from the John Innes collection, was recovered from the North-East Stope, on 35 Level in early 1980, from a cavity in a partially oxidised lens of galena-tennantite ore (Keller & Bartelke, 1982).

The following minerals are reported to form pseudomorphs after schultenite: anglesite (rare, doubtful); arsentsumebite (rare, doubtful); goethite (rare).