| Mineral | Posnjakite |
|---|---|
| Formula | Cu4[(OH)6 | SO4] • H2O |
| Crystal Form | Monoclinic/Domatic [m] |
| Cleavage | [???] Perfect |
| Color | Sky-blue to Dark-blue, may be slightly Greenish-blue |
| Density | 3.4 g/cm3 |
| Diaphaneity | Semitransparent |
| Fracture | Uneven |
| Hardness | 2.5 - 3.0 |
| Lustre | Vitreous |
| Streak | Pale-blue |
| Dana 8 Class | 31.4.1.1 |
| Strunz Class | VI/D.03-10 |
| Mindat | mindat.org |
| WebMineral | WebMineral |
| ID | 138 |