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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).
Localities
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).
Rosasite from Broken Hill - Image
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 zinc-copper
deposit associated with siderite,
malachite, greenockite,
brochantite and
aurichalcite (Mindat, Dana).
Rosasite from the Rosas Mine - Image
At the Ojuela Mine, Mapimí, Mapimí Municipality, Durango, Mexico, rosasite is often found associated with
hemimorphite
(Mindat photos).
Rosasite from the Ojuela Mine - Image
At Tsumeb, Oshikoto Region, Namibia, rosasite pseudomorphs after
malachite after
azurite have been found with cerussite
(KL p181).
Rosasite at Tsumeb forms bluish green mammillary crusts and velvety botryoidal coatings associated with
malachite, azurite,
quartz and cerussite. It also forms
superb pseudomorphs after azurite
which are said to have been found only within the first oxidation zone. Macroscopic crystals of rosasite were
unknown until a pocket in the third oxidation zone was found to contain 2-mm crystals as inclusions in
quartz. Associations can include
chudobaite, willemite, blood-red
cuprite, conichalcite,
duftite, olivenite,
arsentsumebite, cerussite,
smithsonite, hemimorphite,
aurichalcite, dioptase,
calcite, mimetite,
linarite, wulfenite,
otavite, dolomite and
minrecordite.
(Minrec 55.6 supplement p136).
Rosasite from Tsumeb - Image
At the Mariquita Mine (Sultana Mine), Usagre, Badajoz, Extremadura, Spain, rosasite is less abundant than
malachite. It has been found as radial aggregates of pale blue crystals
to a few millimeters in size, associated with calcite,
baryte, calomel,
eglestonite and
terlinguaite. Occasionally rosasite is found associated with
orange eglestonite, forming beautifully colour-contrasting specimens
(MinRec 55.4.506).
Rosasite from the Mariquita Mine -
Image
At the Roughton Gill mine, Roughton Gill, Cumbria, England, UK, rosasite is associated with
hemimorphite (JRS 11.22).
Rosasite from the Roughton Gill Mine - Image
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).
Rosasite from Arizona - Image
At Cerro Gordo, Onyo county, California, USA, rosasite is associated with
smithsonite and
hemimorphite (Dana).
Rosasite from Cerro Gordo - Image
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).
Rosasite from the San Rafael Mine - Image
At the Kelly mine, Socorro county, New Mexico, USA, rosasite is associated with
aurichalcite (Dana).
Rosasite from the Kelly Mine - Image
At the Tintic Mining District, Utah, USA, most commonly rosasite is found as velvety blue spherical masses
coating a matrix of quartz or
goethite, almost always associated with
hemimorphite, and occasionally with
mimetite. Rosasite may coat areas up to several square centimeters.
It has been reported from the Centennial Eureka, Carisa and Mammoth mines and from the upper dumps of the North Star
mine
(MinRec 55.2.221).
Rosasite from Tintic - Image
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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