| Rosasite | |
| Category: | Carbonate mineral |
| Formula: | (Cu,Zn)2(CO3)(OH)2 |
| Imasymbol: | Rss[1] |
| System: | Monoclinic |
| Class: | Prismatic (2/m) (same H-M symbol) |
| Symmetry: | P21/a |
| Unit Cell: | a = 12.873(3) Å, b = 9.354(3) Å c = 3.156(2) Å; β = 110.36(3)°; Z = 4 |
| Strunz: | 5.BA.10 |
| Color: | Blue, bluish green, green |
| Habit: | Acicular crystals as radiating fibrous clusters; botryoidal; mammillary; encrustations |
| Twinning: | On |
| Cleavage: | Perfect on and |
| Fracture: | Splintery, fibrous |
| Tenacity: | Brittle |
| Mohs: | 4 |
| Luster: | Silky, vitreous to dull |
| Refractive: | nα = 1.672 – 1.688 nβ = 1.796 – 1.830 nγ = 1.811 – 1.831 |
| Opticalprop: | Biaxial (−) |
| Birefringence: | δ = 0.139 – 0.143 |
| Pleochroism: | Strong: X = pale emerald green or colourless; Y = dark emerald green or pale blue; Z = dark emerald green or pale blue |
| 2V: | Measured: 33° |
| Streak: | Light blue or green |
| Gravity: | 4–4.2 |
| Solubility: | Effervesces in cold, dilute hydrochloric acid |
| References: | [2] [3] [4] |
| Var1: | Nickeloan rosasite |
| Var1text: | Dark green |
Rosasite is a carbonate mineral with minor potential for use as a zinc and copper ore. Chemically, it is a copper zinc carbonate hydroxide with a copper to zinc ratio of 3:2, occurring in the secondary oxidation zone of copper-zinc deposits. It was originally discovered in 1908 in the Rosas mine in Sardinia, Italy, and is named after the location. Fibrous blue-green rosasite crystals are usually found in globular aggregates, often associated with red limonite and other colorful minerals. It is very similar to aurichalcite, but can be distinguished by its superior hardness.