Galenobismutite

Crystal System: Orthorhombic
Status of Occurrence: Confirmed Occurrence - 1st UK recording
Distribution: Rare
Chemical Composition: Lead bismuth sulphide
Chemical Formula: PbBi2S4
Method(s) of Verification: Parys Mountain - EMPA (Sivaprakash, 1977; Pointon & Ixer, 1980).

Chemical Group:

  • Sulphosalts

Geological Context:

  • Hydrothermal: volcanogenic massive sulphides
Introduction: galenobismutite is an uncommon, generally trace, mineral occurring in bismuth-rich hydrothermal veins and other ore deposits. It tends to occur with other bismuth-bearing sulphosalts and can only be identified by ore petrology and electron microprobe analyses in many of its global occurrences.
Occurrence in Wales: galenobismutite is restricted in its occurrence in Wales to the polymetallic ore deposits of Parys Mountain.

Key Localities:

  • Parys Mountain, Anglesey: galenobismutite was reported on the basis of ore petrology and electron microprobe analysis by Sivaprakash (1977) and by Pointon & Ixer (1980) and occurs as fine-grained (5-20 ┬Ám) intergrowths with bismuthinite, native bismuth, bournonite and kobellite, forming contact-rims around chalcopyrite, galena and tetrahedrite and inclusions in sphalerite. It also forms a cement to framboidal pyrite.

References:

  1. Pointon, C.R. & Ixer, R.A., 1980. Parys Mountain mineral deposit, Anglesey, Wales: geology and ore mineralogy. Transactions of the Institution of Mining and Metallurgy (Section B: Applied earth science), 89, B143-B155.
  2. Sivaprakash, C., 1977. Geochemistry of some sulphides and sulphosalts from Parys Mountain, Anglesey. Unpublished M.Phil. thesis, University of Aston in Birmingham.