Lucchesiite Explained

Lucchesiite
Category:	Cyclosilicates Tourmaline group
Formula:	CaFe3Al6(Si6O18)(BO3)3(OH)3O
Imasymbol:	Lcc^[1]
System:	Trigonal
Class:	Ditrigonal pyramidal (3m) (same H-M symbol)
Symmetry:	R3m
Unit Cell:	a = 16.00, c = 7.21 [Å] (approximated); Z = 3
Color:	Black
Habit:	Thin tablets
Fracture:	Conchoidal
Tenacity:	Brittle
Mohs:	7
Luster:	Vitreous
Streak:	Grey
Density:	3.21 (calc.), 3.24 (meas.) (approximated)
Opticalprop:	Uniaxial (-)
Pleochroism:	Very dark brown to light brown

Lucchesiite is a new member of tourmaline-group of minerals.^[2] Lucchesiite has the formula CaFe₃Al₆(Si₆O₁₈)(BO₃)₃(OH)₃O. It is the calcium and oxygen-analogue of schorl.^[2] 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] [4]}

Notes on chemistry

Impurites in lucchesiite, depending on the provenience, are sodium, magnesium, aluminium, titanium, trivalent iron, and minor vanadium, potassium, manganese and zinc.^[4]

Notes and References

1. Warr. L.N.. 2021. IMA–CNMNC approved mineral symbols. Mineralogical Magazine. 85. 3. 291–320. 10.1180/mgm.2021.43. 2021MinM...85..291W. 235729616. free.
2. Web site: Lucchesiite: Lucchesiite mineral information and data . Mindat.org . 2016-03-04.
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. 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)