Mineral Database

Mineral Database
Mineralogy of Wales

Elyite

Crystal System: Monoclinic
Formula: Pb4Cu(SO4)(OH)8
Status of Occurrence: Confirmed Occurrence - 3rd UK recording
Distribution: Rare
Chemical Composition: Lead copper sulphate hydroxide
Method(s) of Verification: all elyite occurrences in Wales are based on its distinctive purple colour and association.

Thin blades of elyite (purple), up to 0.75 mm long, from Llechweddhelyg Mine, in the Central Wales Orefield. S.A. Rust Collection (no. 1244). Photo M.P. Cooper, © National Museum of Wales.

Violet coloured acicular elyite, from Dolyhir Quarry, Old Radnor, Powys. © D.I. Green.

Chemical Group:
  • Sulphates
Geological Context:
  • Supergene : post-mining oxidation & weathering deposits
  • Supergene : in situ natural oxidation & weathering deposits
Introduction: elyite is occasionally found in the oxidized zones of lead- and copper-bearing ore bodies and, more frequently, in post mining associations within mine tips or in weathered smelter slags. Its stabilization requires relatively alkaline conditions, a property it shares with its most frequent associates such as hydrocerussite, lanarkite and leadhillite group minerals. Elyite is difficult to confuse with other minerals occurring in the post-mining supergene environment due to its striking violet colour.
Occurrence in Wales: elyite was first reported from Wales by Rust & Mason (1988) from Esgairhir Mine in the Central Wales Orefield, where it occurred along with a wide range of other post-mining minerals in old mine-tips. This represented only the third UK occurrence. Three out of the four elyite occurrences in Wales are associated with mine-tip environments in which local highly alkaline conditions occur, for example due to juxtaposition of weathering sulphidic veinstone with lime-mortar debris from collapsed buildings.
Key Localities:
  • Dolyhir Quarry, Old Radnor, Powys: found on a single specimen as minute purple lath-like crystals with lanarkite in a cavity in the oxidation crust of a fragment of massive galena found in fault gouge at the top of the main sulphide vein. Unlike most elyite, this occurrence can definitely be attributed to natural in-situ oxidation of the vein material (N. Hubbard Collection).
  • Esgairhir Mine, Tal-y-bont, Ceredigion: elyite has been found on a small number of micro-specimens as violet, fan-like sprays of crystals up to 0.4 mm in length in association with covelline, anglesite, caledonite, hydrocerussite and an uncharacterized fibrous blue copper mineral (Rust & Mason, 1988).
  • Frongoch Mine, Devil's Bridge, Ceredigion: three specimens were found in the early 1990s in an area of the dumps containing much lime-mortar rubble. The elyite formed minute purple crystals and associated minerals were hydrocerussite and cerussite (Green et al., 1996).
  • Llechweddhelyg Mine, Penrhyncoch, Ceredigion: elyite occurs very rarely at this site in cavities in part-oxidized galena, where it forms small (<1 mm) purple blades associated with an uncharacterized pale green copper mineral (S.A. Rust Collection, specimen no. 1244).
References:
  • 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.
  • Rust, S.A. & Mason, J.S., 1988 The minerals of Esgair-Hir mine, Dyfed, Wales.  UK Journal of Mines & Minerals, 5, 35-43.