Rosasite

Rosasite


Composition: (Cu,Zn)2(CO3)(OH)2
Crystal System : Monoclinic
Colours: Green, bluish-green, sky-blue
Lustre : Velvety, dull
Hardness (H) : 4.5
Specific Gravity (S.G) : 4.0-4.2
References: Gebhard (1999)

Distribution

Rare. First oxidation zone (from surface to 100 m depth; Gebhard, 1999). Third oxidation zone

Occurrence

  • Supergene
  • 1st Oxidation Zone
  • 3rd Oxidation Zone

Notable Finds

In the upper part of the first oxidation zone, pseudomorphs and "double pseudomorphs" after azurite were reasonably common. In the third oxidation zone, macroscopic crystals of rosasite were found - such crystals were hitherto virtually unknown for the species (Gebhard, 1999).

Paragenetic and General Notes

In the upper levels, as bluish-green mamillary crusts and velvety botryoidal coatings; also as superb pseudomorphs after azurite (Pinch and Wilson, 1977). "Double pseudomorphs", in which rosasite replaces (or partly replaces) malachite pseudomorphs after azurite, are notable.

Importantly, rosasite is typically part of the paragenesis in which the rare mineral otavite was found.

In the third oxidation zone as crystals to 2 mm embedded in "blue" quartz, and as crusts of contrasting colour on blood-red cuprite (Gebhard, 1999).

Rosasite has been reported to form pseudomorphs after the following minerals:  azurite (rare); galena (rare); malachite (common, replacing malachite already pseudomorphous after azurite).