Nb-containing titanite, Si-[4](1.000) ([6])(Ti-0.748 Al-0.095 Zr-0.045 Nb-0.041 Ta-0.001 Fe-0.067(3+) Sn-0.002 Sb-0.001)(1.000) ([7])(Ca-0.986 Ce-0.004 La-0.001 Mn-0.004 Na-0.005 K-0.001)(1.001) F-0.055 (OH)(0.065) O-4.880, from San Vito quarry, Mt. Somma, Naples, Italy, is characterised by extensive substitutions in the six- and seven-fold coordination sites. Single-crystal X-ray diffraction study indicates this niobian titanite to be monoclinic (a = 6.557(l), b = 8.701 (1), c = 7.077(l) Angstrom, beta = 113.86degrees) with C2/c symmetry. Crystal structure refinement (agreement factor, R = 0.027) suggests that the substitution mechanism (Al, Fe)(3+) + (Nb, Ta)(5+) = 2Ti(4+) is primarily responsible for the incorporation of pentavalent metal ions in the octahedral site.
Nb-containing titanite: new data and crystal structure refinement / Brigatti, Maria Franca; Caprilli, Enrico; A., Mottana; Poppi, Luciano. - In: NEUES JAHRBUCH FUR MINERALOGIE MONATSHEFTE. - ISSN 0028-3649. - STAMPA. - 3:3(2004), pp. 117-126. [10.1127/0028-3649/2004/2004-0117]
Nb-containing titanite: new data and crystal structure refinement
BRIGATTI, Maria Franca;CAPRILLI, Enrico;POPPI, Luciano
2004
Abstract
Nb-containing titanite, Si-[4](1.000) ([6])(Ti-0.748 Al-0.095 Zr-0.045 Nb-0.041 Ta-0.001 Fe-0.067(3+) Sn-0.002 Sb-0.001)(1.000) ([7])(Ca-0.986 Ce-0.004 La-0.001 Mn-0.004 Na-0.005 K-0.001)(1.001) F-0.055 (OH)(0.065) O-4.880, from San Vito quarry, Mt. Somma, Naples, Italy, is characterised by extensive substitutions in the six- and seven-fold coordination sites. Single-crystal X-ray diffraction study indicates this niobian titanite to be monoclinic (a = 6.557(l), b = 8.701 (1), c = 7.077(l) Angstrom, beta = 113.86degrees) with C2/c symmetry. Crystal structure refinement (agreement factor, R = 0.027) suggests that the substitution mechanism (Al, Fe)(3+) + (Nb, Ta)(5+) = 2Ti(4+) is primarily responsible for the incorporation of pentavalent metal ions in the octahedral site.Pubblicazioni consigliate
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