Lucchesiite

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
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]

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]