Reference:
▪ Panikorovskii T.L., Chukanov N.V., Aksenov S.M., Mazur A.S., Avdontseva E.Yu., Shilovskikh V.V., Krivovichev S.V. (2017): Alumovesuvianite, Ca19Al(Al,Mg)12Si18O69(OH)9, a new vesuvianite-group member from the Jeffrey mine, asbestos, Estrie region, Québec, Canada. Mineralogy and Petrology, 111, 833–842.
Abstract:
Alumovesuvianite (IMA 2016–014), ideally Ca19Al(Al,Mg)12Si18O69(OH)9, is a new vesuvianite-group member found in the rodingite zone at the contact of a gabbroid rock with host serpentinite in the abandoned Jeffrey mine, Asbestos, Estrie Region, Québec, Canada. It occurs as prismatic tetragonal crystals up to 4 × 4 × 6 mm3 in size encrusting walls of cavities in a granular diopside. Associated minerals are diopside, grossular and prehnite. Single crystals of alumovesuvianite are transparent colorless or light pink with a vitreous lustre. The dominant crystal forms are {100}, {110}, {210}, {111}, {101} and {001}. The Mohs hardness is 6.5. The specific gravitiy is Dmeas = 3.31(1) g/cm3 and Dcalc = 3.36 g/cm3, respectively. The mineral is optically uniaxial (−), ω = 1.725(2), ε = 1.722(2). The chemical composition, determined by SEM–WDS (wavelength-dispersive spectroscopy on a scanning electron microscope; all oxides except H2O) and TG (thermogravimety; H2O) analysis, is: SiO2 37.1 wt%, Al2O3 18.8 wt%, CaO 36.6 wt%, MgO 2.48 wt%, Mn2O3 0.67 wt%, Fe2O3 0.22 wt%, H2O 2.61 wt%, total 98.5 wt%. The empirical formula based on 19 Ca atoms per formula unit and taking into account the MAS–NMR (magic-angle spinning nuclear magnetic resonance) data, is: Ca19.00(Al0.92Fe3+0.08)Σ1.00(Al9.83Mg1.80Mn3+0.25)Σ11.88Si17.98O69.16(OH)8.44. The most intense IR absorption bands lie in the ranges 412–609, 897–1024, and 3051–3671 cm−1. The eight strongest lines of the powder X-ray diffraction pattern are (I–d(Å)–hkl): 22–2.96–004, 100–2.761–432, 61–2.612–224, 25–2.593–600, 20–1.7658–831, 20–1.6672–734, 21–1.6247–912, and 22–1.3443–880. Alumovesuvianite is tetragonal, space group P4/n, unit-cell parameters refined from the powder data are a = 15.5603(5) Å, c = 11.8467(4) Å, V = 2868.3(4) Å3, Z = 2. The crystal structure has been refined to R1 = 0.036 for 3098 unique observed reflections with |Fo| ≥ 4σF. The structure refinement provides the bond length of 1.916 Å and the scattering factor for the Y1 site of 16 e−, which is in good agreement with the total occupancy of this site as (Al0.73Mn3+0.20Fe3+0.07)Σ1.00 and is confirmed by the 27Al MAS NMR data. Alumovesuvianite is a new member of the vesuvianite group with Al3+ as a dominant cation in the Y1 site. The name alumovesuvianite is given to highlight the species-defining role of Al.
▪ Panikorovskii T.L., Chukanov N.V., Aksenov S.M., Mazur A.S., Avdontseva E.Yu., Shilovskikh V.V., Krivovichev S.V. (2017): Alumovesuvianite, Ca19Al(Al,Mg)12Si18O69(OH)9, a new vesuvianite-group member from the Jeffrey mine, asbestos, Estrie region, Québec, Canada. Mineralogy and Petrology, 111, 833–842.
Abstract:
Alumovesuvianite (IMA 2016–014), ideally Ca19Al(Al,Mg)12Si18O69(OH)9, is a new vesuvianite-group member found in the rodingite zone at the contact of a gabbroid rock with host serpentinite in the abandoned Jeffrey mine, Asbestos, Estrie Region, Québec, Canada. It occurs as prismatic tetragonal crystals up to 4 × 4 × 6 mm3 in size encrusting walls of cavities in a granular diopside. Associated minerals are diopside, grossular and prehnite. Single crystals of alumovesuvianite are transparent colorless or light pink with a vitreous lustre. The dominant crystal forms are {100}, {110}, {210}, {111}, {101} and {001}. The Mohs hardness is 6.5. The specific gravitiy is Dmeas = 3.31(1) g/cm3 and Dcalc = 3.36 g/cm3, respectively. The mineral is optically uniaxial (−), ω = 1.725(2), ε = 1.722(2). The chemical composition, determined by SEM–WDS (wavelength-dispersive spectroscopy on a scanning electron microscope; all oxides except H2O) and TG (thermogravimety; H2O) analysis, is: SiO2 37.1 wt%, Al2O3 18.8 wt%, CaO 36.6 wt%, MgO 2.48 wt%, Mn2O3 0.67 wt%, Fe2O3 0.22 wt%, H2O 2.61 wt%, total 98.5 wt%. The empirical formula based on 19 Ca atoms per formula unit and taking into account the MAS–NMR (magic-angle spinning nuclear magnetic resonance) data, is: Ca19.00(Al0.92Fe3+0.08)Σ1.00(Al9.83Mg1.80Mn3+0.25)Σ11.88Si17.98O69.16(OH)8.44. The most intense IR absorption bands lie in the ranges 412–609, 897–1024, and 3051–3671 cm−1. The eight strongest lines of the powder X-ray diffraction pattern are (I–d(Å)–hkl): 22–2.96–004, 100–2.761–432, 61–2.612–224, 25–2.593–600, 20–1.7658–831, 20–1.6672–734, 21–1.6247–912, and 22–1.3443–880. Alumovesuvianite is tetragonal, space group P4/n, unit-cell parameters refined from the powder data are a = 15.5603(5) Å, c = 11.8467(4) Å, V = 2868.3(4) Å3, Z = 2. The crystal structure has been refined to R1 = 0.036 for 3098 unique observed reflections with |Fo| ≥ 4σF. The structure refinement provides the