Mawbyite, (w. Wulfenite)

Mawbyite


Composition: Pb(Fe3+,Zn)2(AsO4)2(OH,H2O)2
Crystal System : Monoclinic
Colours: Orange-brown, reddish-brown
Lustre : Adamantine
Hardness (H) : 4
Specific Gravity (S.G) : 5.53

 

Distribution

Very rare. Second oxidation zone (30 Level).

Occurrence

  • Supergene
  • 2nd Oxidation Zone

Paragenetic and General Notes

Mawbyite is a member of the tsumcorite group of minerals, and was first described in 1989 from Broken Hill, New South Wales, Australia.

Specimens of "red tsumcorite" were found at Tsumeb in the 1970s and '80s, and Gebhard (1999) suggested that "red tsumcorite may represent the mineral mawbyite" but he was unable to offer proof at that time.

The first analytical verification of mawbyite from Tsumeb appears to have been in 2004 (Prof. Terry Seward, private communication to Rob Lavinsky, dated 23/12/2004).

The best specimens, believed to be from the second oxidation zone, comprise rich but partial encrustations of red, sub-mm mawbyite crystals on tennantite-rich ore, with etched, tan-coloured wulfenite crystals to 6 mm.