Kobellite

Crystal System: Orthorhombic
Status of Occurrence: Confirmed Occurrence - 1st UK recording
Distribution: Rare
Chemical Composition: Lead copper bismuth antimony sulphide
Chemical Formula: Pb22Cu4(Bi,Sb)30S69
Method(s) of Verification: Parys Mountain - EMPA (Sivaprakash, 1977).

Chemical Group:

  • Sulphosalts

Geological Context:

  • Hydrothermal: volcanogenic massive sulphides
Introduction: kobellite is occasionally found as a minor mineral in hydrothermal ore deposits with other sulphosalts and sulphides. There are only a few localities worldwide. As with many of the sulphosalt minerals, kobellite is not easy to identify without resorting to detailed analytical techniques.
Occurrence in Wales: the first and only Welsh occurrence of kobellite at Parys Mountain was recorded by Sivaprakash (1977) and was the first record of the mineral in the UK.

Key Localities:

  • Parys Mountain, Anglesey: kobellite forms as fine-grained intergrowths 5-20 ┬Ám in size, associated with native bismuth, bismuthinite, galenobismutite and bournonite, in contact rims around chalcopyrite, galena and tetrahedrite group minerals. It was also present as inclusions in sphalerite and as a cement to framboidal pyrite (Pointon & Ixer, 1980).

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 Unpublished M.Phil.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.