Formula: (Cu,Zn)₂(CO₃)(OH)₂  Cu:Zn ratio is near 3:2.

Species: Carbonates

Colour: Blue, blue-green to green, sky-blue; colourless to light blue in transmitted light.

Lustre: Vitreous, Silky

Hardness: 4½

Specific Gravity: 4 – 4.2

Crystal System: Monoclinic

Member of: Rosasite Group

Name: Named in 1908 by Domenico Lovisato after its discovery locality, the Rosas Mine, Sulcis, Sardinia, Italy.

Type Locality: Rosas Mine Complex (Rosas Mine), Narcao, South Sardinia Province, Sardinia, Italy

Rosasite is a secondary mineral found in the oxidation zone of copper-zinc deposits.