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
CategoryCyclosilicates
Tourmaline group
Formula
(repeating unit)
CaFe3Al6(Si6O18)(BO3)3(OH)3O
IMA symbolLcc[1]
Crystal systemTrigonal
Crystal classDitrigonal pyramidal (3m)
(same H-M symbol)
Space groupR3m
Unit cella = 16.00, c = 7.21 [Å] (approximated); Z = 3
Identification
ColorBlack
Crystal habitThin tablets
FractureConchoidal
TenacityBrittle
Mohs scale hardness7
LusterVitreous
StreakGrey
Density3.21 (calc.), 3.24 (meas.) (approximated)
Optical propertiesUniaxial (-)
PleochroismVery dark brown to light brown
References[2][3][4]

Notes on chemistry

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

References

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  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. ^ 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)
  3. ^ 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
  4. ^ a b c "Lucchesiite: Lucchesiite mineral information and data". Mindat.org. Retrieved 2016-03-04.