Crystal structure of zirconium-rich seidozerite

Abstract

The crystal structure of seidozerite was refined (a Siemens P4 diffractometer, MoKalpha radiation, It 80 independent reflections, anisotropic refinement, R = 0.053). The monoclinic unit-cell parameters are a = 5.627(1) Å, b = 7.134(1) Å, c = 18.590(4) Å, beta = 102.68(1)°, sp. gr. P2/c, Z = 4. The structural formula, Na1.6Ca0.275Mn0.425Ti0.575Zr0.925[Si2O7]OF, agrees well with the results of the electron probe analysis. Seidozerite is demonstrated to belong to the meroplesiotype polysomatic series including the structures of more than 30 titano- and zirconosilicates

Crystal Chemistry of the Rosenbuschite Group

“…The M5 site is occupied by Ti. These results is in good agreement with the cation distribution found in a different specimen of seidozerite by Pushcharovskii et al (2002) except for the M2b position, which in their specimen is dominated by Ca. The variety of cations occupying the M positions in the rosenbuschite group of minerals have quite different ionic radii and valences.…”

From structure topology to chemical composition. XII. Titanium silicates: the crystal chemistry of rinkite, Na2Ca4REETi(Si2O7)2OF3

“…Rastsvetaeva et al (1991) stated that the lower symmetry of rinkite from Khibiny is due to the order of REEs and Ca and concluded that their model is in good agreement with all previous work. Christiansen et al (1999) and Christiansen and Rønsbo (2000) analysed the s t r u c t u r a l r e l a t i on be t w e e n g ö t z e n i t e [Ca 2 Ca 2 NaCa 2 Ti(Si 2 O 7 ) 2 OF 3 , space group P1; Table 1] and rinkite and stated that the models of Rastsvetaeva et al (1991) and Galli and Alberti (1971) are the same except for the lower symmetry of the first due to minor ordering of some cations. As noted above, the latest structure refinement of rinkite was done by Sokolova and Cámara (2008a) and is in good agreement with the work of Galli and Alberti (1971).…”

“…= 3.45 g cm À3 , with an approximate formula (Ti,Nb,Al,Zr)(Na,Ca) 3 (Ca,Ce) 4 (Si 2 O 7 ) 2 (O,F) 4 . Rastsvetaeva et al (1991) refined rinkite from the Khibiny massif, Kola Peninsula, Russia: a = 5.679, b = 7.412, c = 18.835 Å , a = 101.26º, V = 777.6 Å 3 , space group P2 1 , Z = 2, D calc. = 3.36 g cm À3 , with the structural formula {TiF (O,F)…”

“…**For mosandrite, a simplified formula is given; it is not possible to write a structural formula for mosandrite as its simplified formula does not give the stoichiometry for the main cations and anions. References (the latest reference on the structure is the first entry in the numbered list of references): (1) Sokolova and Cámara (2008a); Rastsvetaeva et al (1991), Belov (1968), Tê-yü et al (1965), Kheirov et al (1963); (2) Sokolova and Hawthorne (2008b); (3) Christiansen et al (2003a), Pushcharovskii et al (2002), Simonov and Belov (1960), Skszat and Simonov (1966); (4) Bellezza et al Alberti (1971) stated that their results were in good agreement with the structure of Simonov and Belov (1968). Rastsvetaeva et al (1991) stated that the lower symmetry of rinkite from Khibiny is due to the order of REEs and Ca and concluded that their model is in good agreement with all previous work.…”

“…References (the latest reference on the structure is the first entry in the numbered list of references): (1) Sokolova and Cámara (2008a); Rastsvetaeva et al (1991), Belov (1968), Tê-yü et al (1965), Kheirov et al (1963); (2) Sokolova and Hawthorne (2008b); (3) Christiansen et al (2003a), Pushcharovskii et al (2002), Simonov and Belov (1960), Skszat and Simonov (1966); (4) Bellezza et al Alberti (1971) stated that their results were in good agreement with the structure of Simonov and Belov (1968). Rastsvetaeva et al (1991) stated that the lower symmetry of rinkite from Khibiny is due to the order of REEs and Ca and concluded that their model is in good agreement with all previous work. Christiansen et al (1999) and Christiansen and Rønsbo (2000) analysed the s t r u c t u r a l r e l a t i on be t w e e n g ö t z e n i t e [Ca 2 Ca 2 NaCa 2 Ti(Si 2 O 7 ) 2 OF 3 , space group P1; Table 1] and rinkite and stated that the models of Rastsvetaeva et al (1991) and Galli and Alberti (1971) are the same except for the lower symmetry of the first due to minor ordering of some cations.…”