Lucchesiite
From Wikipedia, the free encyclopedia
Lucchesiite is a new member of tourmaline-group of minerals.[4] Lucchesiite has the formula CaFe3Al6(Si6O18)(BO3)3(OH)3O. It is the calcium and oxygen-analogue of schorl.[4] It has two co-type localizations, one in Czech Republic and the other in Sri Lanka. As the other members of the tourmaline group, it is trigonal.[3][2]
CategoryCyclosilicates
Tourmaline group
Tourmaline group
FormulaCaFe3Al6(Si6O18)(BO3)3(OH)3O
| Lucchesiite | |
|---|---|
| |
| General | |
| Category | Cyclosilicates Tourmaline group |
| Formula | CaFe3Al6(Si6O18)(BO3)3(OH)3O |
| IMA symbol | Lcc[1] |
| Crystal system | Trigonal |
| Crystal class | Ditrigonal pyramidal (3m) (same H-M symbol) |
| Space group | R3m |
| Unit cell | a = 16.00, c = 7.21 [Å] (approximated); Z = 3 |
| Identification | |
| Color | Black |
| Crystal habit | Thin tablets |
| Fracture | Conchoidal |
| Tenacity | Brittle |
| Mohs scale hardness | 7 |
| Luster | Vitreous |
| Streak | Grey |
| Density | 3.21 (calc.), 3.24 (meas.) (approximated) |
| Optical properties | Uniaxial (-) |
| Pleochroism | Very dark brown to light brown |
| References | [2][3][4] |
