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]
Lucchesiite | |
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General | |
Category | Cyclosilicates Tourmaline group |
Formula (repeating unit) | 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] |
Notes on chemistry
editImpurites in lucchesiite, depending on the provenience, are sodium, magnesium, aluminium, titanium, trivalent iron, and minor vanadium, potassium, manganese and zinc.[2]
References
edit- ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- ^ a b c Bosi, F., Skogby, H., Ciriotti, M.E., Gadas, P., Novák, M., Cempírek, J., Všianský, D., and Filip, J., 2016. Lucchesiite, CaFe2 3Al6(Si6O18)(BO3)3(OH)3O, a new mineral species of the tourmaline supergroup. Mineralogical Magazine 80(1)
- ^ a b Bosi, F., Skogby, H., Ciriotti, M.E., Gadas, P., Novák, M., Cempírek, J., Všianský, D., and Filip, J., 2015. Lucchesiite, IMA2015-043. CNMNC Newsletter No. 27, October 2015, page ; Mineralogical Magazine 79, 1229–1236
- ^ a b c "Lucchesiite: Lucchesiite mineral information and data". Mindat.org. Retrieved 2016-03-04.