Images
Formula: Cu4(SO4)(OH)6.2H2O
Hydrated sulphate containing hydroxyl, paramorph of
wroewolfeite. Both minerals are monoclinic.
Crystal System: Monoclinic
Specific gravity: 3.48 to 3.5 measured
Hardness: 2½ to 3
Streak: Greenish blue
Colour: Blue, greenish-blue
Solubility: Insoluble in water. Readily soluble in acids or ammonia.
Environments
Langite is an uncommon but widespread secondary mineral
in the oxidation zone of
copper sulphide deposits; it may be of post-mine formation,
and it may be altered to brochantite (HOM, Mindat). Associated minerals include
wroewolfeite, posnjakite,
serpierite, devilline,
chalcophyllite, connellite,
brochantite, malachite and
gypsum
(HOM).
Localities
The Two Mile and Three Mile deposits, Paddy's River, Paddys River District, Australian Capital Territory, Australia,
are skarn deposits at the contact between
granodiorite and volcanic rocks.
langite is a secondary sulphate occurring in crusts
generally associated with brochantite
(AJM 22.1.43).
At Kintore, Broken Hill, New South Wales, Australia, langite is found only as intergrowths with
ktenasite
(AJM 3.1.43).
At St-Rome-de-Tarn, Aveyron, France, langite occurs as crystals to 5 mm on baryte
(Dana).
At Canaveille, Pyrenees, France, posnjakite and
langite pseudomorphs after
calcite have been found
(KL p193).
There are two co-type localities, both in Cornwall, England, UK. One is St Just, and the other is Fowey Consols,
Tywardreath and Par.
At the Driggith and Sandbed mines, Caldbeck, Cumbria, England, UK, langite is widespread as a component of
crusts surrounding fragments of
copper-rich ore on the dumps, associated with brochantite and
linarite; it is sometimes partly replaced by
brochantite
(JRS 9.39-44).
At Red Gill mine, Roughton Gill, Caldbeck, Cumbria, England, UK, langite is very rare, but it has been found
associated with
caledonite, and separately associated with
brochantite
and covellite
(JRS 11.29-47).
At Roughton Gill mine, Caldbeck, Cumbria, England, UK, langite is very rare, but has been found on a matrix of
chalcopyrite and quartz
(JRS 14.14).
At Silver Gill, Roughton Gill, Caldbeck, Cumbria, England, UK, langite crystals commonly occur with crusts of
hemimorphite, and associated with
cerussite,
linarite, malachite,
brochantite and redgillite.
Many specimens of
langite are partly pseudomorphed by
brochantite
(JRS 8(2).85-97).
At the Ward mine, about 18 miles south of Ely, Nevada, USA, langite has been found in a suite of supergene lead and
copper minerals in the
Caroline tunnel. The langite occurs as minute crystals which coat superficially altered
chalcopyrite in a quartz
gangue.
Among the supergene minerals present, brochantite and
cerussite are the earliest to crystallise, followed by approximately contemporaneous
serpierite, langite and linarite.
Langite and
serpierite may be replaced by devilline
(AM 49.1143-1145).
Back to Minerals