Scotlandite

Crystal System: Monoclinic
Status of Occurrence: Unconfirmed Occurrence
Distribution: See individual species entries for details
Chemical Composition: Lead sulphite
Chemical Formula: PbSO3
Method(s) of Verification: not verified

Geological Context:

  • Supergene: in situ natural oxidation & weathering deposits
Introduction: scotlandite is an extremely rare supergene lead mineral which occurs (on the type material from Leadhills in Scotland) in association with anglesite, susannite, leadhillite and lanarkite (Paar et al., 1984). Its rarity even within this localized mineral association is indicative of a relatively narrow field of stability: in more open oxidation systems, galena oxidizes via anglesite to cerussite: minerals like leadhillite are just interim products of this process and normally dissolve to be replaced by cerussite.
Occurrence in Wales: scotlandite is rumoured to have been collected in well-formed free-standing, transparent, adamantine, tabular crystals (to 2 mm!) from Machen Quarry in Mid Glamorgan, in the late 1980s (Plant & Jones, 1995). It has not been found since despite much fieldwork and detailed examinations of specimens in both private and public collections, and even the identity of the collector(s) responsible for the 'find' remains a mystery. Under these circumstances it has to be concluded that scotlandite is a highly dubious Welsh species, and will remain so unless credible evidence for its existence in Wales comes to light.

Key Localities:

There are no key localities for this specimen.

References:

  1. Paar, W.H., Braithwaite, R.S.W., Chen, T.T. & Keller, P., 1984. A new mineral, scotlandite (PbSO3) from Leadhills, Scotland; the first naturally occurring sulphite. Mineralogical Magazine, 48, 283-288.
  2. Plant, S.P. & Jones, I.E., 1995. Minerals of Machen Quarry, Mid Glamorgan, Wales. Journal of the Russell Society, 6(1), 31-36.