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Formula: (Zn,Cu)5(CO3)2(OH)6
Carbonate
Crystal System: Monoclinic
Specific gravity: 3.96 measured, 3.93 calculated
Hardness: 2
Streak: White to light blue
Colour: Light blue, bluish and greenish blue
Solubility: Moderately soluble in hydrochloric, sulphuric and nitric acid
Common impurities: Ca
Environments:
Aurichalcite is a supergene mineral occuring in
the oxidation zone of hypothermal (high temperature) veins in copper and
zinc deposits. It is far more common in the
carbonate-rich English Pennines than in carbonate-deficient deposits
(JRS 18.15).
Localities
At Kintore, Broken Hill, New south Wales, Australia, aurichalcite occurs rarely associated with
hemimorphite and smithsonite,
and also as drusy crusts mixed with hydrozincite. At Block 14 aurichalcite
has been found as crusts on cerussite and
azurite crystals
(AJM 3.1.35).
At the Shangri La mine, Kimberley, Western Australia, aurichalcite may be overgrown by
hemimorphite
(AJM 16.1.19).
At Aghbar, Agdz Cercle, Zagora Province, Drâa-Tafilalet Region, Morocco, aggregates to 0.5 mm of sharp platy crystals of
aurichalcite have been found in a dolomite boulder enriched in sulphides
and shot through with erythrite
(Minrec 38.5.360-361).
The type locality is the Loktevskoye Mine, Upper Loktevka River, Altai Krai, Russia.
At the Roughton Gill mines, Caldbeck, Allerdale, Cumbria, UK, aurichalcite is not rare, but it is not as common
as rosasite. A specimen has been found with a spray of aurichalcite on
quartz. Hemimorphite and
rosasite are common associates of aurichalcite here
(JRS 14.8).
At Red Gill mine, Roughton Gill, Caldbeck, Allerdale, Cumbria, UK, aurichalcite is very rare, but it has been found
as aggregates a few tenths of a millimetre in length, in iron stained
quartz, sometimes associated with
hemimorphite
(JRS 11.33).
At Silver Gill, Roughton Gill, Caldbeck, Allerdale, Cumbria, UK, aurichalcite has been found with
rosasite, and also associated with
brochantite and langite, on the
mine dumps. It is relatively common as crystals up to about 1 mm in length on
hemimorphite in partly oxidised
sphalerite-rich veinstone in the upper workings. Aurichalcite is later
in the paragenesis than hemimorphite
(JRS 8(2).89).
At the Golconda mine, Brassington, Derbyshire, England, UK, aurichalcite has been found on
baryte
(RES p108).
At Millclose mine, Darley Dale, Matlock Bath, Derbyshire, England, UK, aurichalcite has been found on
calcite
(RES p98).
At Rutland Cavern, Heights of Abraham, Matlock Bath, Derbyshire, England, UK, aurichalcite occurs with
rosasite on fluorite or
calcite
(RES p51).
At Long Tor mine, Matlock, Derbyshire, England, UK, aurichalcite has been found with
fluorite
in a cavity in calcite
(RES p73).
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