...Zhi LIN; João ROCHA Abstract The small-pore framework stannosilicate Na 2 SnSi 4 O 11 .2H 2 O (Sn-AM-3), exhibiting the structure-type of the rare mineral penkvilksite-2 O , has been synthesized via a seeded hydrothermal process. The estimated cell dimensions are: a = 16.52, b = 8.80, c = 7.48 Å...

...Barbara L. Sherriff; Bing Zhou Abstract Simulations of 29 Si and 23 Na MAS NMR spectra indicate the presence of differing proportions of two polytypes and a third phase in three samples of penkvilksite, Na 4 Ti 2 Si 8 O 22 ·5H 2 O. The most abundant peaks are assigned to the 2 O and 1 M polytypes...

...Stefano Merlino; Marco Pasero; Gilberto Artioli; Alexander P. Khomyakov Abstract The nomenclature of the mineral species penkvilksite, Na 4 Ti 2 Si 8 O 22 ·4H 2 O, has been revised, after the second finding in nature of the mineral, which has been demonstrated to occur in two polytypic...

... of the powder diffraction pattern [ d in Å ( I ) ( hkl )] are: 8.40 (10) (100), 5.38 (9) (111̅), 4.00 (8) (111), 3.401 (9) (202̅), 2.902 (9) (211), 2.691 (9) (131̅). The crystal structure of tumchaite was refined to R = 0.043 for 865 F o > 4σ( F o ). The mineral is isotypic with penkvilksite-1 M...

... not previously been described in minerals (Hawthorne et al. , 2019 ). We can relate kalyuzhnyite-(Ce) to penkvilksite, Na 2 TiSi 4 O 11 ⋅2H 2 O (Bussen et al. , 1974 ; Merlino et al. , 1994 ; Cadoni and Ferraris, 2008 ) and tumchaite, Na 2 (Zr,Sn)Si 4 O 11 ⋅2H 2 O (Subbotin et al. , 2000 ), two silicate...

...Figure 13. (010) (a) and (001) (b) projections of the mixed framework of penkvilksite. ...

... with different levels of titanium for zirconium substitution has been reported ( Lin et al. 1999b ). AM-3 is the synthetic counterpart of the mineral penkvilksite, found at Mont Saint-Hilaire and Kola Peninsula, with formula Na 4 Ti 2 Si 8 O 22 •5H 2 O. Penkvilksite occurs in two polytypic modifications...

... 4 ) Nesosilicate Olivine Orth. Nahcolite Na(HCO 3 ) Carbonate Mon. Nyerereite Na 2 Ca(CO 3 ) 2 Carbonate Orth. Parisite-(Ce) CaCe 2 (CO 3 ) 2 F 2 Carbonate Bastnäsite–Synchysite polysome Mon/Trig. pseudo Hex. Penkvilksite Na 2 Ti(Si 4 O 11 )·2H 2 O...

...Figure 38. 2D net shown in (a) is a basis for 3D nets in the structures of penkvilksite-2 O (b) and penkvilksite-2 M (c). The nets shown in (b) and (c) are different in the stacking order of the 2D nets. ...

... Zr-analogue of penkvilksite-1 M ; structure Monoclinic: P 2 1 / c a 9.144, b 8.818, c 7.537 Å, β 113.22° Colorless; vitreous; translucent to transparent Biaxial (−), α 1.570, β 1.588, γ 1.594, 2 V (meas.) 60°, 2 V (calc.) 60° 8.40(10), 5.38(9), 4.00(8), 3.401(9), 2.902(9...

..., penkvilksite, and other titanosilicates , J. Phys. Chem. B , 101 , 7114 – 7120 . Lin , Z. , Rocha , J. , Ferreira , P. , Thursfield , A. , Agger , J.R. , Anderson , M.W. ( 1999 ): Synthesis and structural characterization of microporous framework zirconium silicates . J...