Lucchesiite

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]

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]}

Notes on chemistry

Impurites in lucchesiite, depending on the provenience, are sodium, magnesium, aluminium, titanium, trivalent iron, and minor vanadium, potassium, manganese and zinc. ^[2]

References

1. 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.
2. 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)
3. 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
4. "Lucchesiite: Lucchesiite mineral information and data". Mindat.org. Retrieved 2016-03-04.