Bindheimite

Crystal System: Cubic
Status of Occurrence: Confirmed Occurrence
Distribution: Locally Abundant
Chemical Composition: Lead antimony oxide hydroxide
Chemical Formula: Pb2Sb2O6(O,OH)
Method(s) of Verification: Bwlch Mine - IR (G. Ryback, unpublished data); Bwlchrhennaid Mine - XRD (NHM, 6335F); Frongoch Mine - XRD (NMH, x13502); Goginan Mine - XRD (NHM, 6718F); Logaulas Mine - XRD (NMW X-1321); Machen Quarry - XRD (NMW-853).

Chemical Group:

  • Oxides & Hydroxides

Geological Context:

  • Supergene: in situ natural oxidation & weathering deposits
Bright yellow, powdery bindheimite in veinstone from Penycefn Mine, in the Central Wales Orefield. Specimen 8 cm long. National Museum of Wales Collection (NMW 2003.1G.M.447) ex J.S. Mason Collection. Photo T.F. Cotterell, © National Museum of W
Powdery, pale yellow bindheimite within cellular quartz. Frongoch Mine, in the Central Wales Orefield. Field of view 10 cm wide. National Museum of Wales Collection (NMW 2003.17G.M.14a). Photo T.F. Cotterell, © National Museum of Wales.
Introduction: a secondary mineral, belonging to the stibiconite group, commonly found in the oxidized zone of antimony-bearing lead deposits.
Occurrence in Wales: bindheimite was first described from Wales by Russell (1944), who described brownish-yellow to honey-yellow alteration crusts on semseyite from Bwlch Mine near Deganwy in North Wales. Confirmation of this occurrence was later made by Ryback (unpublished infra-red data, quoted in Bevins, 1994). In Central Wales bindheimite is widespread, as an alteration product of decayed galena and ullmannite. Jones & Moreton (1977) described powdery yellow bindheimite in cavities in quartz from Frongoch and Eaglebrook mines. At Frongoch and Eaglebrook, the cavities are the result of total decay of antimony-bearing galena, probably in part, due to fine inclusions of ullmannite within the galena. Occasionally, pseudomorphs showing direct replacement of larger, discrete, cubic ullmannite crystals are recorded. Particulary, at Hendrefelen, Frongoch and Mynyddgorddu mines. In terms of abundance, the richest sites for bindheimite in Central Wales are Frongoch and Logaulas where, bright yellow, powdery masses liberally coat cerussite-lined cavities in intensely weathered galena-rich veinstone. Further south, bindheimite is recorded, again, in association with altered galena, from Machen (Plant & Jones, 1995) and Ochrwyth (Bevins & Mason, 2000) quarries in South Wales. At Machen bindheimite occurs as typical powdery, canary-yellow coatings on galena (Plant & Jones, 1995). Bindheimite is potentially more widespread. The inconspicuous nature of powdery coatings, likely results in many collectors ignoring its presence

Key Localities:

  • Bwlch Mine, Deganwy, Gwynedd: bindheimite is recorded replacing both semseyite (Russell, 1944) and stibnite (Ryback, unpublished data quoted in Bevins, 1994) from the shaft dumps. Russell (1944) describes brownish-yellow bindheimite, forming a crust on altered granular semseyite, and a resinous honey-yellow crystalline crust allied to or identical to bindheimite investing crystallized semseyite. Bevins (1994) records bindheimite as light brown crusts on stibnite and quartz.
  • Bwlchrhennaid Mine, Goginan, Ceredigion: resinous to powdery yellow masses are recorded by S. Rust (Cooper, 1987).
  • Eaglebrook (Nantycagl) Mine, Ceulanymaesmawr, Ceredigion: rare in comparison to some Central Wales sites. Jones & Moreton (1977) and Jones (1983) describe bindheimite from Eaglebrook as, typical yellow, powdery masses associated with fine-grained galena on the most westerly dumps.
  • East Penycefn Mine, Bont-goch, Ceredigion: an unusually rich occurrence. Bindheimite was formerly common, along with cerussite and pyromorphite prior to obliteration of the site (Bevins & Mason, 1997).
  • Frongoch Mine, Devil's Bridge, Ceredigion: Jones & Moreton (1977) describe yellow, powdery bindheimite in quartz cavities. Bindheimite is common at Frongoch, occurring abundantly on the extensive dumps, as pale yellow, powdery coatings within sugary quartz associated, with cerussite. Green et al. (1996) note that resinous cubic pseudomorphs after ullmannite, are frequently observed.
  • Gwaithgoch Mine, Pontrhydygroes, Ceredigion: bindheimite is abundant on surface dumps below the vein outcrop, forming yellow powdery patches replacing altered ullmannite.
  • Hendrefelin Mine, Ysbyty Ystwyth, Ceredigion: bindheimite occurs as pseudomorphs showing direct replacement of cubic ullmannite crystals (Clark & Rust, 1993).
  • Logaulas Mine, Ysbyty Ystwyth,Ceredigion: bindheimite is common, as rich, yellow, powdery masses associated with cerussite in opencast workings.
  • Machen Quarry, Caerphilly, South Wales: Bevins (1994) reported that yellow antimony-bearing coatings on galena were thought to be bindheimite. This has proved to be the case with, bindheimite now known to occur commonly, as powdery, canary-yellow coatings within cavities in galena (Plant & Jones, 1995). Cerussite and anglesite crystals developed within galena cavities are frequently encrusted with bindheimite.
  • Mynydd Gorddu Mine, Bontgoch, Ceredigion: Clark & Rust (1993) list bindheimite as one of the supergene species found at Mynyddgorddu. Bindheimite is known to replace ullmannite (Bevins & Mason, 1997).

References:

  1. Bevins, R.E., 1994. A Mineralogy of Wales National Museum of Wales, Geological Series No. 16, Cardiff, 146pp.
  2. Bevins, R.E. & Mason, J.S., 1998. Welsh Metallophyte and metallogenic evaluation project: Results of a Minesite Survey of Gwynedd. National Museums of Wales, Cardiff.
  3. Bevins, R.E. & Mason, J.S., 1997. Welsh metallophyte and metallogenic evaluation project: Results of a minesite survey of Dyfed and Powys. CCW Contract Science Report No. 156. National Museums & Galleries of Wales.
  4. Bevins, R.E. & Mason, J.S., 2000. Welsh Metallophyte and metallogenic evaluation project: Results of a Minesite Survey of Glamorgan and Gwent. National Museums & Galleries of Wales, Cardiff
  5. Clark, A.M. & Rust, S.A., 1993. Bottinoite, a mineral new to Britain. Mineralogical Magazine. 57, 543-544.
  6. Cooper, M.P., 1987. New finds. British Micromount Society Newsletter, 20, 6-9.
  7. Green, D.I., Rust, S.A. & Mason, J.S., 1996. Classic British mineral localities: Frongoch Mine, Dyfed. UK Journal of Mines & Minerals, 17, 29-38.
  8. Jones, A.D., 1983. Nant-y-Cagl. Mineral Realm, 3, 42-76.
  9. Jones, J.A. & Moreton, N.J.M., 1977. The Mines and Minerals of Mid-Wales 40pp.
  10. Plant, S.P. & Jones, I.E., 1995. Minerals of Machen Quarry, Mid Glamorgan, Wales. Journal of the Russell Society, 6(1), 31-36.
  11. Russell, A., 1944. Notes on some minerals either new or rare in Britain. Mineralogical Magazine, 27, 1-10.