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Formula: Cu2+3(Cu,Zn)(OH)6Cl2
Hydroxyhalide, atacamite group. Paratacamite (trigonal)
contains essential zinc, therefore it is not a
paramorph of atacamite
(orthorhombic).
Specific gravity: 3.74
Hardness: 3
Streak: Green
Colour: Green to greenish-black
Solubility: Readily soluble in acids
Common impurities: Zn
Environments:
Hydrothermal environments
Fumeroles
Paratacamite is a secondary copper mineral formed by the alteration of
other copper minerals by chloride waters under cold conditions, in the oxidised zones of some copper deposits, especially in arid climates.
Also in fumarolic deposits and as a weathering product of sulphides in subsea black smoker deposits (Webmin, HOM). Associated minerals
include atacamite and eriochalcite
(Mindat).
Localities
At Kintore, Broken Hill, Broken Hill district, Yancowinna county, New South Wales, Australia, paratacamite has been found rarely
on dump specimens, as crystals to 1 mm lining small cavities in quartz -
chalcocite - malachite lode material
(AJM 3.1.35 ).
At the Carr Boyd Rocks Ni mine, Menangina Station, Menzies Shire, Western Australia, paratacamite-(Ni)
Cu3(Ni,Cu)Cl2(OH)6 is a
secondary mineral formed by the oxidation of
pentlandite in a saline environment, and associated with
gypsum, gillardite and
spangolite
(AJM 17.1.39-44).
At the Francon quarry, Montréal, Quebec, Canada, a single sample of paratacamite has been found, as finely granular aggregates
associated with baddeleyite on fluorite
(Minrec 37.1.41).
There are two co-type Localities, the Generosa mine and the Herminia mine, both at Caracoles, Sierra Gorda, Antofagasta Province,
Antofagasta, Chile. Here paratacamite is associated with clinoatacamite,
schwartzembergite, caracolite,
osarizawaite-beaverite,
boleite and atacamite
(Mindat, HOM).
At the Lily mine, Pisco Umay, Ica, Peru, pseudomorphs of paratacamite
after atacamite have been found
(Minrec 39.2.106).
Alteration:
Paratacamite is easily synthesised and occurs as one of the corrosion products of copper and brass exposed to salt-containing air,
and as an alteration product of nantokite and
eriochalcite
(AM 36.384).
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