Pezzottaite
| Pezzottaite | |
|---|---|
| General | |
| Category | Cyclosilicate minerals |
| Formula | Cs(Be2Li)Al2Si6O18 |
| IMA symbol | Pez |
| Crystal system | Trigonal |
| Crystal class | Ditrigonal pyramidal (3m) (same H-M symbol) |
| Space group | R3c |
| Identification | |
| Color | Raspberry red, orange-red, pink |
| Crystal habit | flattened, tabular, equant, aggregate |
| Cleavage | Imperfect; basal |
| Fracture | Conchoidal to uneven |
| Tenacity | brittle |
| Mohs scale hardness | 8 |
| Luster | Vitreous |
| Streak | White |
| Specific gravity | 3.10 |
| Optical properties | uniaxial |
| Refractive index | 1.601 to 1.620 |
| Birefringence | −0.008 to 0.011 |
| Pleochroism | Moderate dichroic |
| References | |
Pezzottaite, marketed under the name raspberyl or raspberry beryl, is a mineral species first recognized by the International Mineralogical Association in September 2003. Pezzottaite is a caesium analogue of beryl, a silicate of caesium, beryllium, lithium and aluminium, with the chemical formula Cs(Be2Li)Al2Si6O18. Named after Italian geologist and mineralogist Federico Pezzotta, pezzottaite was first thought to be either red beryl or a new variety of beryl ("caesium beryl"); unlike actual beryl, however, pezzottaite contains lithium and crystallizes in the trigonal crystal system rather than the hexagonal system.