Elyite

minerals

chenite

serpierite

hydrocerussite

Formula: CuPb4(SO4)O2(OH)4.H2O
Anhydrous sulphate containing hydroxyl
Specific gravity: 6
Hardness: 2
Streak: Pale violet to white
Colour: Purple
Solubility: Insoluble in water, turns white in dilute nitric or hydrochloric acid (Dana)
Environments

Hydrothermal environments

Elyite forms as a slag mineral in lead-rich environments in old smelters, where an alkaline environment is created by the weathering of lime mortar. It also forms in the highly alkaline assemblages caused by the use of medieval fire-setting methods to extract ore, in which case massicot and minium are typically associated with the elyite. Much more rarely elyite occurs naturally in the oxidation zones of lead-zinc deposits, where it appears to have formed by low temperature post-mining oxidation processes (M&M 25.35-36, MW). Associated minerals include galena, langite, serpierite, cerussite, anglesite, litharge and minium (HOM). Elyite requires relatively alkaline conditions for its stabilisation, a property it shares with its most frequent associates hydrocerussite, lanarkite and leadhillite (MW).

Localities

At Greystone quarry, near Launceston, Lezant, Cornwall, England, UK, rare elyite has formed by natural supergene oxidation. Associated minerals include galena, quartz, chalcopyrite and cerussite (M&M 25.35-36).

At Redgill mine, Caldbeck Fells, Cumbria, England, UK, naturally formed elyite has been reported as minute crystals on a fracture in a galena-chalcopyrite matrix, associated with chenite and hydrocerussite (JRS 11.36). It has also been found at Driggith mine, Red Gill mine and Short Grain, which are also at Caldbeck Fells. Some of the elyite may be of post-mining origin but the largest crystals, which are associated with well formed bladed chenite crystals, are more likely to have been produced by supergene oxidation in situ in the vein (JRS 12.54).

At Frongoch mine, Devil's Bridge, Ceredigion, Wales, UK, elyite has been found on the dumps in an area containing much lime-mortar rubble, as minute crystals associated with hydrocerussite and cerussite (MW).

At a site excavating a Roman lead smelter, near Llancynfelyn, Ceredigion, Wales, UK, a single central cavity was found lined with a thin crust of hydrocerussite and containing a sheaf of laths of elyite to 1.5 mm. The specimen is clearly original veinstone which has been subjected to heat but not the intense heating that one would expect within a smelter. The formation of litharge associated with cerussite may have been brought about by fire-setting, a known Roman mining technique. Lead oxide minerals such as litharge and minium are typically associated with elyite where fire-setting has taken place. The lead oxides form from the alteration of lead minerals such as cerussite, and subsequent interaction with water produces highly alkaline solutions from which basic lead oxysalts such as elyite, hydrocerussite and lanarkite crystallise (JRS 17.32-35 ).

At Llechweddhelyg mine, Penrhyncoch, Ceredigion, Wales, UK, elyite to 1mm occurs very rarely in cavities in partially oxidised galena (MW).

At Esgairhir mine, Tal-y-bont, Ceredigion, Wales, UK, elyite has been found on a small number of micro-specimens as sprays of crystals to 0.4 mm in association with covellite, anglesite, caledonite and hydrocerussite (MW).

At Dolyhir quarry, Old Radnor, Powys, Wales, UK, elyite has been found on a single specimen as minute crystals with lanarkite in a cavity in the oxidation crust of a fragment of massive galena. This occurrence can definitely be attributed to natural in-situ oxidation of the vein material (MW).

At the type locality, the Caroline tunnel, Ward Mine, White Pine county, Nevada, USA, elyite occurs in voids in massive chalcopyrite, sphalerite, galena and pyrite with only minor amounts of euhedral quartz as gangue. In those areas showing incipient oxidation, elyite was found with langite, serpierite and supergene galena. Voids in the sulphide masses tend to be partly filled with earthy galena, and elyite crystals occur in this material. Langite and serpierite are formed later. In specimens exhibiting still later minerals such as brochantite or cerussite the elyite had disappeared (AM 57.364-367).

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