Mineral Database

Mineral Database
Mineralogy of Wales

Brianyoungite

Crystal System: Orthorhombic,Monoclinic
Formula: Zn12(CO3,SO4)(OH)4
Status of Occurrence: Confirmed Occurrence
Distribution: Rare
Chemical Composition: Zinc carbonate sulphate hydroxide
Method(s) of Verification: Elgar Mine - XRD & EMPA (National Museum of Wales, X-ray film no. NMW X-1268, specimen NMW 98.35G.M.973); Frongoch Mine - XRD (Manchester Museum, X-ray film no. MANCH:XRD734, Manchester Museum specimen, MANCH:N17115).

Scanning electron micrograph of thin bladed brianyoungite crystals in clusters on quartz from Elgar Mine. National Museum of Wales specimen (NMW 98.35G.M.973). © National Museum of Wales.

Scanning electron micrograph of clusters of subparallel bladed brianyoungite crystals on quartz from Elgar Mine. National Museum of Wales specimen (NMW 98.35G.M.973). © National Museum of Wales.

Geological Context:
  • Supergene : post-mining oxidation & weathering deposits
Introduction: brianyoungite is a rare post-mining mineral which forms as part of supergene lead-zinc-copper assemblages.
Occurrence in Wales: brianyoungite was identified from Elgar and Frongoch mines in the Central Wales Orefield in 2000 (Cotterell et al., 2003), forming inconspicuous white spherulitic and rosetted aggregates composed of bladed microcrystals. In both occurrences the primary vein material consists of the Central Wales Orefield late simple or 'A2' mineralization proposed by Mason (1994).
Key Localities:
  • Elgar Mine, Bontgoch, Ceredigion: Extremely rare, as minute rosettes (to 0.3 mm across) of pearly white lath-like crystals coating a single specimen of iron-stained quartz and galena from the deep adit dumps (Cotterell et al., 2003).
  • Frongoch Mine, Devil's Bridge, Ceredigion: Spherulitic aggregates of pearly white lath like crystals up to 0.5 mm across in galena-rich matrix (Cotterell et al., 2003).
References:
  • Cotterell, T.F., Mason, J.S. & Green, D.I., 2003 Brianyoungite from Elgar Mine and Frongoch Mine, Ceredigion, Wales.  Journal of the Russell Society, 8(1), 33-34.
  • Mason, J.S., 1994 A Regional Paragenesis for the Central Wales Orefield.  Unpublished M.Phil thesis, University of Wales (Aberystwyth).