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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
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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