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(a) T net with hexagonal rings of silicon–oxygen tetrahedra (a) and cuts from this net: (b) amphibole ribbon and (c) pyroxx ene chain; (d) heteropolyhedral H net with the ratio T : D = 2 : 1 and cuts from this net: (e) longitudinal H ribbon and (f) transverse H ribbon; and heteropolyhedral H net with the ratios T : D = (g) 4 : 1 and (h) 6 : 1.
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In view of new data on the chemical composition and structure of a series of natural layered silicates containing three-layer blocks and their corresponding microporous minerals with related fragments, their structural features; the structural conditionality of their properties; their transformation in the presence of isomorphism, decationation, an...
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... extended in one dimension. Figg ures 1b and 1c show octahedral chains of the minii mum width (one octahedron) which are cut from the layer in two directions: longitudinally and transversely, respectively. The silicate components of blocks are the most diverse. With allowance for their configuration, the following types of modules can be selected (Fig. ...
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... The [Т ∞∞ O ∞∞ Т ∞∞ ] module is characterized by the maximum extension of all components. The О layer consists of edgeesharing octahedra (Fig. 1a), and the Т layer is a tetrahedral net composed of sixxmemm bered rings (Fig. ...
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... was the first to note the relationship between heterophyllosilicates and minerals of mica group [1] if to replace each second row of [Si 2 O 7 ] diorthogroups along the [100] direction with rows of Ti octahedra (fiveevertex Ti polyhedra) (Fig. 2d). He called this group "titanosilicate ...
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... and c = 5.30 Å. In contrast to the previous minerals, the chesterite structure can be represented by two types of modules (Fig. 16). The O ribbons of both modules consist of Mg octahedra but are characterized by diff ferent widths: [4 × 4] and [2 × 3]. Accordingly, the Si ribbon of the first module is wide, being composed of three pyroxene chains (Figs. 2b+2c), whereas in the second module it is composed of two pyroxene chains and is an amphibole Si ribbon (Fig. ...
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... modules (Fig. 16). The O ribbons of both modules consist of Mg octahedra but are characterized by diff ferent widths: [4 × 4] and [2 × 3]. Accordingly, the Si ribbon of the first module is wide, being composed of three pyroxene chains (Figs. 2b+2c), whereas in the second module it is composed of two pyroxene chains and is an amphibole Si ribbon (Fig. ...
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... a "cement" mineral. Natuu rally, he considered columns of edgeesharing Ca octaa hedra to be the basis of the cuspidine architecture and, according to Belov [1], the cuspidine structure is traa ditionally described as being composed of tilleyite ribb bons of Ca octahedra, between which Si 2 O 7 groups are located at different levels (Fig. ...
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... due regard for the chemical and structural relatedness with heterophyllosilicates, we propose an alternative description of cuspidine and other minerals of this group, with the selection of blocks based on the [Н ∞ О ∞ Н ∞ ] module (Fig. 20b). Here, the role of silii con-oxygen amphibole ribbon plays the "transverse" cut from the titanosilicate net, which is parallel to diorthogroups (Fig. 2f). The quadruple О ribbon is also a transverse cut from the О layer (Fig. 1c). Here, two unittcell parameters are retained, which correspond to 5 (×2) and 7 Å. The differences in the ...
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... relatedness with heterophyllosilicates, we propose an alternative description of cuspidine and other minerals of this group, with the selection of blocks based on the [Н ∞ О ∞ Н ∞ ] module (Fig. 20b). Here, the role of silii con-oxygen amphibole ribbon plays the "transverse" cut from the titanosilicate net, which is parallel to diorthogroups (Fig. 2f). The quadruple О ribbon is also a transverse cut from the О layer (Fig. 1c). Here, two unittcell parameters are retained, which correspond to 5 (×2) and 7 Å. The differences in the representaa tives of this group are mainly in the way the positions of the О ribbon are filled: either entirely by Ca (cuspii dine) or by Na, Zr, Ca, and Nb ...
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... 2 , the block core is a quadruple ribb bon composed of Ca octahedra. Blocks aggregate into a framework structure via the free vertices of Si tetraa hedra of diorthogroups with Ca octahedra of О and Н ribbons. The channels contain Ca atoms in the octaa hedral coordination and F atoms, which occupy free vertices of Ca octahedra of the О ribbon (Fig. 20). Another example of highhfuorine mineral is burpalite Na 2 СaZr(Si 2 O 7 )F 2 from the Burpalinskii alkaline massif (Northern Zabaykalye, Russia) [126]. The block core is a quadruple ribbon composed of Na, Zr, and Ca octahedra. The О ribbon is formed by two rows of Na octahedra, which are built up on both sides by Zr and Ca octahedra. ...
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Citations
... Framework titanosilicates of the heterophyllosilicate family [6,[11][12][13], whose structures are based on three-layer HOH modules, where the central O-layer is formed by edge-sharing M-octahedra and external H-layers are represented by a network of SiO 4 tetrahedra and Tiϕ 6 octahedra (or Tiϕ 5 semi-octahedra), possess a microporous structure and are characterized by the occurrence of systems of wide intersecting (perrotite group) or parallel channels (astrophyllite supergroup, nafertisite group, veblenite). From the experimental data and theoretical calculations it was previously found [14] that in mineral caryochroite (nafertisite structure type), ion exchange is possible in counter flows for Na + , K + , Rb + , Cs + , Ag + , and Pb 2+ ions, and for lithium ions possible exchange between the neighboring channels with the formation of twodimensional conductivity, was also established. ...
... Adjacent HOH modules can be connected to each other via common vertices of TiX 6 octahedra forming a heteropolyhedral quasi-framework. Based on the (Si 2 O 7 ):TiX n ratio, several structural groups are distinguished among the heterophyllisilacate family: bafertisite (1:1), astrophyllite (2:1), and nafertisite (3:1) [10][11][12]. Crystal structures of some members of the bafertisite group (e.g. members of the perraultite-jinshajiangite solid-solution series) are based on heteropolyhedral frameworks which contain two-dimensional system of penetrated channels, while members of the astrophyllite and nafertisite groups contain systems of parallel channels running in one direction. ...
Ion-exchange properties of natural caryochroite (Na,Sr)3{(Fe,Mg)²⁺10(OH)6[TiO(Si6O17)(OH)0.5]2}·8H2O, a microporous heterophyllosilicate with a one-dimensional system of broad zeolytic channels, related to nafertisite Na3{Fe²⁺10(OH)6[TiO(Si6O17)F0.5]2}·2H2O, were studied in reactions with 1 N aqueous solutions of Rb, Cs, Ag, and Pb nitrates at 50 °C. In reactions with Rb⁺, Cs⁺, and Pb²⁺, sodium is partly replaced by nearly equivalent amounts of larger cations. In reactions with Pb²⁺ and Ag⁺, additional processes involving H2O molecules take place: replacement of two H2O molecules with Pb²⁺ + 2OH⁻ and replacement of H2O molecule with Ag⁺ + OH⁻, respectively. The geometrical-topological analysis of ion migration pathways in the nafertisite-type structures carried out using an approach based on the Voronoi-Dirichlet partition has shown that only Na⁺ cations occurring at the centers of wide channels can take part in reactions with large alkaline cations proceeding in counter flows. In the reaction with Ag⁺, additional Na⁺ ions are involved. Li⁺ cations having a smaller radius can pass through the window between the channels, forming a 2D conducting layer.
... Generally speaking, fedorite belongs to the reyerite-gyrolite group [9] and has a modular structure [10,11], since it consists of packed modules of tetrahedral (T) and octahedra (O) sheets sharing according to the schematic sequence OT2 2O. Combined [T∞∞O∞∞T∞∞] modules in the crystal structure of fedorite were also discussed in [12]. ...
Fedorite is a rare phyllosilicate, having a crystal structure characterized by SiO4-tetrahedral double layers located between continuous layers formed by edge-sharing (Ca,Na)-octahedra, and containing interlayer K, Na atoms and H2O molecules. A mineralogical-petrographic and detailed crystal-chemical study of fedorite specimens from three districts of the Murun alkaline complex was performed. The sequence of the crystallization of minerals in association with fedorite was established. The studied fedorite samples differ in the content of interlayer potassium and water molecules. A comparative analysis based on polyhedral characteristics and deformation parameters was carried out. For the first time, EPR, optical absorption and emission spectra were obtained for fedorite. The raspberry-red coloration of the mineral specimens could be attributed to the presence of Mn 4+ ions.
... Lomonosovite belongs to heterophyllosilicates [8,9] and has unit-cell sizes, chemical composition, and symmetry and topological characteristics close to those of β-lomonosovite (primarily) and vuonnemite, whose simplified formulas are, respectively, Na 5+x Ti 4 (7) [14]. The summarized data on all currently known structural and chemical varieties of β-lomonosovite and its generalized formula were given in [15]. ...
A new niobium-rich lomonosovite variety with a high degree of ordering of Ti and Nb atoms has been investigated by X-ray diffraction analysis and electron probe microanalysis. Its simplified formula is Na 10 Ti 2 (Nb,Fe,Ti) 2 (Si 2 O 7) 2 (PO 4) 2 O 4. The triclinic unit-cell parameters are a = 5.411(1) Å, b = 7.108(1) Å, c = 14.477(2) Å, α = 99.78(1)°, β = 96.59(1)°, γ = 90.26(1)°, V = 544.94(5) Å 3 , Z = 1, sp. gr. P1. The crystal structure has been refined to the final reliability factor R = 6.3% within the anisotropic approximation of atomic displacements using 3674 reflections with F > 3σ(F). The problem of niobium distribution in minerals with structures of lomonosovite and related types is discussed.
... 0000, 0-0 www.zaac.wiley-vch.de of modules ( Figure 6) and can be described in terms of modular crystallography. [51,52] Module I with composition Sr(UO 2 )(V 2 O 7 ) is a uranyl pyrovanadate double heteropolyhedral layer in which the voids are filled by Sr atoms. Along [001] module I alternates with uranium-free module II. ...
Uranyl vanadate compounds with divalent cations, M(UO2)(V2O7) (M = Ca, Sr) and Sr3(UO2)(V2O7)2, were synthesized by flux crystal growth, and their crystal structures were solved using single-crystal X-ray diffraction data. Ca(UO2)V2O7 and Sr(UO2)V2O7 were synthesized from reactants with molar ratios M:U:V of 1:1:2 and identical heating conditions, and increasing the M:U:V ratio to 3:1:4 resulted in Sr3(UO2)(V2O7)2. Crystallographic data for M(UO2)V2O7 compounds are: a = 7.1774(18) Å, b = 6.7753(17) Å, c = 8.308(2) Å; V = 404.01(18) Å3; sp. gr. Pmn21, Z = 2 for Ca; a = 13.4816(11) Å, b = 7.3218(6) Å, c = 8.4886(7) Å; V = 837.91(12) Å3; sp. gr. Pnma, Z = 4 for Sr. Compound Sr3(UO2)(V2O7)2 has a = 6.891(3) Å, b = 7.171(3) Å, c = 14.696(6) Å, α = 85.201(4)˚, β = 78.003(4)˚, γ = 89.188(4)˚; V = 707.9(5) Å3; sp. gr. P-1, Z = 2. The framework structure of Sr(UO2)(V2O7) is related to that of Pb(UO2)(V2O7) reported previously, while that of Ca(UO2)(V2O7) has a different topology. The topological polymorphism of the [(UO2)(V2O7)]-type framework may be due to the differing ionic radii of the guest M2+ cations. Compound Sr3(UO2)(V2O7)2 has a modular structure based on two different types of electroneutral layers: [Sr(UO2)(V2O7)] and [Sr2(V2O7)]. Structural complexities were calculated, and Raman spectra were collected and their peaks were assigned
... Analyzing the crystal structure of the pyroxmangite group representatives, one can distinguish onedimensional oblong ТОТ ∞ blocks, extended in the [011] direction; their external parts are silicon-oxygen chains [Si 7 O 21 ] 14-, while the central part is a wide chain formed by M-cation polyhedra [22]. The blocks are arranged in checkerboard order to form a heteropolyhedral quasi-framework (Fig. 3a). ...
The pyroxferroite and pyroxmangite from xenoliths of aluminous gneisses in the alkaline basalts of Bellerberg paleovulcano (Eifel, Germany) have been studied by electron-probe and X-ray diffraction methods and IR spectroscopy. The parameters of the triclinic unit cells are found to be a = 6.662(1) Å, b = 7.525(1) Å, c = 15.895(2) Å, α = 91.548(3)°, β = 96.258(3)°, and γ = 94.498(3)° for pyroxferroite and a = 6.661(3) Å, b = 7.513(3) Å, c = 15.877(7) Å, α = 91.870(7)°, β = 96.369(7)°, and γ = 94.724(7)° for pyrox-mangite; sp. gr. P. The crystallochemical formulas (Z = 2) are, respectively, M(1–2) (Mn 0.5 Ca 0.4 Na 0.1) 2 M(3–6) (Fe, Mn) 4 M7 [Mg 0.6 (Fe, Mn) 0.4 ][Si 7 O 21 ] and M(1–3) (Mn, Fe) 3 M(4–6) [(Fe, Mn) 0.7 Mg 0.3 ] 3 M7 [Mg 0.5 (Fe, Mn) 0.5 ][Si 7 O 21 ]. For these and previously studied representatives of the pyroxmangite structural type, an analysis of the cation distribution over sites indicates wide isomorphism of Mn 2+ , Fe 2+ , and Mg in all cation M(1–7) sites and the preferred incorporation of Сa and Na into large seven-vertex M1O 7 and M2O 7 polyhedra and Mg into the smallest five-vertex M7O 5 polyhedron.
... The HOH modules are also related by inversion centres, and the symmetry groupoid is simpler than that for lamprophyllite: λ-PO P1 and σ-PO P1 (Fig. 8). Inversion centre as a symmetry operation is present in the disordered schüllerite-like mineral with the space group P1 () whereas, in ordered minerals, with the schüllerite structure and the space group P1 (Rastsvetaeva et al., 2011Rastsvetaeva et al., , 2014), it is realized only as a pseudo-symmetry operation. ...
... The A1 site is occupied by Ba, whereas the A2 site is generally Na-dominant and is split into three subsites, A2ʹ, A2ʹ' and A2ʹ''. The composition of the A2ʹ site is The type IV is represented by schüllerite, ideally Ba 2 [Table 3, Fig. 10), a lamprophyllite-like heterophyllosilicate mineral discovered in the Löhley basalt quarry, Eifel volcanic region, Germany (Chukanov et al., 2011; Rastsvetaeva et al., 2011). In heterophyllosilicates, including minerals of the lamprophyllite group, the (Si 2 O 7 ) groups are strongly distorted due to their bonding both to large interlayer cations such as Ba, Sr, and K, and small M octahedra occupied by Ti in lamprophyllite, Mg in lileyite, Fe 3+ in emmerichite and ericssonite, etc. ...
... (online version in colour) Fig. 10. The crystal structure of schüllerite (Rastsvetaeva et al., 2011; Chukanov et al., 2011): general view (a) and O sheet (b). (online version in colour) 924 R. K. Rastsvetaeva et al. ...
The crystal structures of the lamprophyllite-related minerals are based upon HOH modules consisting of a central octahedral O sheet sandwiched between two heteropolyhedral H sheets. The general crystal-chemical formula for these minerals can be written as [10–11] A 2 [[6] M 1[6] M 22[6]2 M 3 X 2] [[5] L 2(Si2O7)2O2], where the contents of the O and H sheets are given in square brackets in this order and A = Ba, Sr, K, Na,; M 1 = Na, Mn2+; M 2 = Na, Mn2+, Fe2+, Ca; M 3 = Ti, Mn2+, Mg, Fe3+, Fe2+; L = Ti, Fe3+; X = OH, O, F. According to the unit-cell parameters and symmetry, lamprophyllite-related minerals can be subdivided into five structure types: I (monoclinic polytypes, C 2/ m ); II (orthorhombic polytypes, Pnmn ), III (nabalamprophyllite, BaNa[Na3Ti (OH)2][Ti2(Si2O7)2O2], monoclinic, P 2/ m , with an ordered arrangement of the interlayer Ba2+ and Na+ cations), IV (triclinic, P 1) and V (triclinic, ![Formula][1] ). The triclinic members (types IV and V) include schullerite and its analogues, which differ from the lamprophyllite-group minerals sensu stricto in their symmetry and topology of the HOH modules. The end-member formulae of lamprophyllite-related minerals and the position of schullerite in the ranks of heterophyllosilicates are discussed.
[1]: /embed/mml-math-1.gif
... Currently, the lamprophyllite group is assigned to the heterophyllosilicate family [6][7][8][9][10], the crystal structure of which is based on a three-layer HOH module. The inner O layer of this module consists of edge-sharing MО 6 octahedra, while the outer heteropolyhedral H layers are formed by Si 2 O 7 diorthogroups, linked by L five-vertex polyhedra. ...
The variations in the chemical composition of lamprophyllite-group minerals from a peralkaline dyke of the Mokhnatye Roga area (Kandalaksha region, Kola Peninsula), which are crystallized during the entire period of dyke formation and form several generations, have been investigated. The early generations differ in a steadily high fluorine content, while the later ones exhibit reduced amount of fluorine, impurity elements, and sodium, with a simultaneous increase in the potassium content. The crystal structure of fluorine rich barytolamprophyllite (potentially a new representative of the lamprophyllite group, differing by the predominance of fluorine in the anion X site) has been analyzed by single crystal X-ray diffraction. This mineral is found to have a monoclinic unit cell with the following parameters: a = 19.5219(8) Å, b = 7.0915(2) Å, c = 5.3925(2) Å, β = 96.628(3)°, and sp. gr. C2/m. The structure is refined to R = 5.73% in the anisotropic approximation of the atomic displacement parameters using 3668I > 2σ(I). The idealized formula (Z = 2) is (Ba,Sr) 2 [Na(Na,Fe) 2 (Ti,Mg)F 2 ][Ti 2 (Si 2 O 7) 2 O 2 ].
... The structure type of amphiboles is characterized by infinite (along the shortest period 5.3 Å) amphibole-type ribbons of T (1)(2) tetrahedra. The gaps between ribbons contain rods composed of edge-sharing M(1-3) octahedra, which jointly form three-layer TOT ∞ blocks [5]. B cations in the M(4) eight-vertex polyhedra are located at two sides of the octahedral ribbon. ...
... Minerals of the amphibole supergroup are characterized by macro-and microtwinning [2,5]; however, twins were not observed among lithium minerals of the pedrizite family. The purpose of this study was to perform a single-crystal X-ray diffraction analysis of the new mineral, ferro-pedrizite, and describe the specific features of its microtwinning. ...
Abstract—The structure of ferro-pedrizite—a new lithium mineral of the amphibole supergroup—has been
studied by single-crystal X-ray diffraction. Fe2+ ions dominate over Mg in the chemical composition of this
mineral. The parameters of the monoclinic unit cell are a = 9.3716(4) Å, b = 17.649(1) Å, c = 5.2800(6) Å,
and β = 102.22(1)°. The experimental set of intensities contains a large number of significant reflections (~10%),
which violate the C lattice. Consideration of pseudomerohedral twinning (matrix [1 0 0/0 0/–3/4 0 ]) allowed
us to solve and refine the structure within the sp. gr. C2/m to the final value R = 3.9% in the anisotropic
approximation of atomic displacements using 4843I > 2σ(I). The twin components are found to be
0.681(3)/0.319(3). Twinning has been revealed for the first time in amphiboles of the pedrizite family. The
idealized formula of ferro-pedrizite (Z = 2) is determined as NaLi2(Fe Al2Li)[Si8O22](OH)2.
... The characteristics of the coordination polyhedra are presented in Table 4. eight-vertex polyhedra (Fig. 2). The ribbons are sandwiched between tetrahedral silicon-oxygen chains to form a three-layer TOT ∞ module [12]. The main difference between the minerals with the bustamite and wollastonite structure types is that the tetrahedral silicon-oxygen chains in the former structure type are connected to the octahedral ribbon without a shift along the a axis [5] (Fig. 3). ...
A specimen of iron-rich bustamite from the Broken Hill deposit (Australia) has been studied by single-crystal X-ray diffraction and by Mössbauer and IR spectroscopy. The triclinic unit-cell parameters are as follows: a = 7.1301(4) Å, b = 7.6940(3) Å, c = 7.7345(4) Å, α = 79.352(4)°, β = 62.951(6)°, γ = 76.149(3)°, V = 365.49(3) Å 3 , sp. gr. P. The structure is solved by direct methods and refined to R = 5.22% based on 7298 reflections with |F| > 4σ(F). The mineral under study is similar in composition and structure to the Fe-rich bustamite described earlier. It is found that all iron atoms are in the divalent state and occupy the М1 and М3 sites in a ratio of 33: 67. The idealized formula of iron-rich bustamite from Broken Hill (Z = 1) is Mn 2 Ca 2 (Fe,Mn)Ca[Si 3 O 9 ] 2 .
