Aurichalcite

carbonate

copper mineral

Formula: (Zn,Cu)5(CO3)2(OH)6
Carbonate
Specific gravity: 3.6 to 4.3
Hardness: 2
Streak: White to light blue
Colour: Light blue, bluish and greenish blue
Solubility: Moderately soluble in hydrochloric, sulphuric and nitric acid
Environments:

Hydrothermal environments

Aurichalcite is a copper/zinc 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).

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 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, auricha1cite 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).

Common impurities: Ca

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