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Formula: CuZn(CO3)(OH)2
Anhydrous carbonate containing hydroxyl, rosasite group
Crystal System: Monoclinic
Specific gravity: 4 to 4.2 measured, 4.15 calculated
Hardness: 4½
Streak: Light blue
Colour: Blue, blue-green to green, sky-blue; colourless to light blue in transmitted light.
Solubility: Soluble in acids.
Common impurities: Mg,Fe
Environments:
Rosasite is an uncommon secondary mineral found in the
oxidation zone of copper-zinc deposits, typically formed by
zinc-bearing solutions acting on
primary copper minerals; it may be of
post-mine origin
(Mindat, HOM). Associated minerals include malachite,
aurichalcite, hydrozincite
and hemimorphite (HOM).
Rosasite is far more common in the carbonate-rich English Pennines than in carbonate-deficient deposits
(JRS 18.15).
At Broken Hill, New south Wales, Australia, rosasite occurs occasionally with
smithsonite and
hemimorphite, and also on massive
quartz-cerussite
aggregates, sometimes overgrowing malachite (AJM 3.39).
At the Shangri La mine, Kimberley, Western Australia, rosasite occurs as crusts on
hemimorphite,
smithsonite or matrix (AJM 16.1.22).
At the Braeside lead field, Pilbara, Western Australia, rosasite is intergrown with
hemimorphite and
cerussite, and also occurs in association with
hydrozincite (AJM 13.2.60).
At the type locality, the Rosas Mine, Narcao, Carbonia-Iglesias Province, Sardinia, Italy, rosasite occurs
in the oxidised zone of a -copper deposit associated with siderite,
malachite, greenockite,
brochantite and
aurichalcite (Mindat, Dana).
At the Ojuela Mine, Mapimí, Mapimí Municipality, Durango, Mexico, rosasite is often found associated with
hemimorphite
(Mindat photos).
At Tsumeb, Namibia, rosasite is associated with malachite,
smithsonite and
hydrozincite (Dana). Rosasite
pseudomorphs after malachite after
azurite have been found with cerussite
(KL p181).
At the Roughton Gill mine, Roughton Gill, Cumbria, England, UK, rosasite is associated with
hemimorphite (JRS 11.22).
At Silver Gill, Roughton Gill, Cumbria, England, UK, rosasite is associated with
aurichalcite,
hemimorphite and
malachite (JRS 8-2.93).
In Arizona, USA, rosasite occurs in quartz vugs associated with
brochantite,
cerussite, hemimorphite,
malachite, and
smithsonite (R&M 90.4.345).
At Cerro Gordo, Onyo county, California, USA, rosasite is associated with
smithsonite and
hemimorphite (Dana).
At the San Rafael mine, Nye county, Nevada, USA, rosasite is associated with
hemimorphite, mimetite
and cerussite, all on a matrix of spongy vein
quartz (R&M 85.6.521).
At the Kelly mine, Socorro county, New Mexico, USA, rosasite is associated with
aurichalcite (Dana).
At Roughton Gill, Caldbeck, Allerdale, Cumbria, England, UK, rosasite is associated with
hemimorphite
(JRS 11.3.28).
At the Kabwe mine, Central Province, Zambia, rosasite has been found associated with
malachite, and also as inclusions in
mottramite (R&M 94.2.134)
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