...Maxwell C. Day; Frank C. Hawthorne Abstract A structure hierarchy is developed for chain-, ribbon- and tube-silicate based on the connectedness of one-dimensional polymerisations of (TO 4 ) n − tetrahedra, where T = Si 4+ plus P 5+ , V 5+ , As 5+ , Al 3+ , Fe 3+ , B 3+ , Be 2+ , Zn 2+ and Mg 2...

.... Each uranyl phosphate studied has a topologically identical anionic sheet of uranyl square bipyramids and phosphate tetrahedra combined with various cations (Li + , Na + , K + , Rb + , Cs + , Mg 2+ , Ca 2+ , Ba 2+ ) and water in the interlayer. Uranyl peroxides formed under many of the experimental...

... Å, respectively, from Shannon 1976 ) and divalent electric charge that does not balance efficiently the negative charge of oxide anions in corner-shared tetrahedra. Iron(III), however, with a trivalent charge and smaller radius (tetrahedral ionic radius of 0.57 Å; Whittaker and Muntus 1970...

...+ and Fe 3+ ions in neighboring T(3) tetrahedra. When both configurations are present, the crystal assumes a shade of green, depending on their relative proportion. The electrons released by the irradiation are trapped at sites which are probably associated with water molecules in the beryl channels...

... plane leads to a highly disrupted coordination, where only half of the tetrahedra are restored. This makes a contact twin highly unlikely. The reported twin is actually a penetration twin, in which the irregular composition surface may have compensated, to some extent, the unfavourable structural match...

..., which demonstrate the remarkable diversity of Cu 2+ mixed-ligand coordination environments. The crystal structure of dokuchaevite is based on OCu 4 tetrahedra that share common corners thus forming [O 2 Cu 6 ] 8+ single chains. Two of the eight symmetrically independent copper atoms do not form Cu–O...

... of both minerals comprise heteropolyhedral slabs of composition [ XM 1 Fe 2 3 + (OH) 2 (PO 4 ) 4 ], that are linked together via corner-sharing of PO 4 tetrahedra with isolated [ M 2(O p ) 2 (H 2 O) 4 ] octahedra. The structures differ in the mode of linkage of the M 2 octahedra, which is via trans O p...

... 2 ) 2 ] polyhedra which share the four hydroxyl oxygen atoms with the Zn-centred tetrahedra. The main bands in the Raman spectrum of qatranaite are related to vibrations in Zn OH 4 2 - tetrahedra (cm −1 ): 297, 344 (ν 2 + ν 4 ); 440, 449, 479 (ν 1 + ν 3 ); 990 (νZn–O–Zn); 1065 (νZn–OH). Strong bands...

.... The chains are corner-connected along [100] to linear corner-shared trimers of Fe-centred octahedra and along [010] via corner-connected PO 4 tetrahedra. Monoclinic kenngottite is structurally related to triclinic souzalite and gormanite. It is named in honor of the prominent mineralogist Prof. Gustav Adolf...

... that of the latter (11.86 Å 3 ); the T O 4 tetrahedra in the blue diopside (<λ tet > =1.006; σ θ(tet) 2 = 24.37–24.69) are less distorted than that of the green diopside (<λ tet > = 1.007; σ θ(tet) 2 = 27.94); the M 1O 6 octahedra in the former (<λ oct > =1.006; σ θ(oct) 2 = 20.39–21.13) are more...

... tetrahedra, linked by the corners and edges. Adjacent layers are held together by six- and four-coordinated Na and six-coordinated K polyhedra. The eight strongest diagnostic lines of the X-ray powder diffraction pattern are ( I , d in Å , hkl ]: 44, 10.37, 020; 47, 5.47, 200; 47, 4.84, 220; 17, 3.76, 240...

... chains of uranyl pentagonal bipyramids linked by sulfate tetrahedra to form sheets. The sheets are linked to each other through bonds to interlayer NH 4 + groups and octahedrally coordinated Mn 2+ , and by hydrogen bonds from H 2 O groups. Redcanyonite is named for Red Canyon in southeast Utah, USA...

... and chloride. The crystal structure of eztlite contains mitridatite-like layers, with a repeating triangular nonameric [ ${\rm Fe}_9^{3 +} $ O 36 ] 45– arrangement formed by nine edge-sharing Fe 3+ O 6 octahedra, decorated by four trigonal pyramidal Te 4+ O 3 groups, compared to PO 4 or AsO 4 tetrahedra...

... species with, respectively, n and n–1 bridging O atoms. The formulation in parentheses, (NH 2 ), (CH 3 ), and (OH), is meant to indicate that those functional groups replace one or more oxygen in the silicate tetrahedra. There is no evidence for O-NH 2 or O-CH 3 bonding. Therefore, a solution of reduced C...

... are formed by corner sharing mixed-ligand ZnO 3 Cl tetrahedra and SO 4 tetrahedra. The topology of [ZnSO 4 Cl] – layers in belousovite is identical to [Si 4 O 10 ] 4– layers in the minerals of the apophyllite group. A review of mixed-ligand ZnO m Cl n coordination polyhedra in minerals and inorganic...

... fragment contains a ditrigonal ring made of Si-bearing tetrahedra, above the center of which is the X cation (or vacancy) in ninefold coordination. Below the ring is a triad made of Y O 6 octahedra, of which each is connected through shared edges with two Z O 6 octahedra and through shared apices...

... reflections and 249 parameters. Phase I is a mixed-anion silicate and contains insular [SiO 4 ] tetrahedra as well as [Si 2 O 7 ] dimers in the ratio 2:1. The cation distribution of the sodium, potassium and calcium ions among the eight different non-tetrahedral M -sites has been studied by simultaneously...

... 3 and ν 4 vibrations become unresolvable due to the weak intensity or overlapping during heating, indicating a decrease of the Davydov splitting, which is probably due to the change of PO 4 tetrahedra at high temperature. Γ (PO 4 internal) = 6A g  + 3E 1g  + 6E 2g With increasing...

... structure of vanderheydenite ( R 1 = 0.0497 for 939 reflections with F o > 4σ F ) contains chains of edge-sharing ZnO 6 octahedra parallel to a that are linked by edge- and corner-sharing ZnO 5 trigonal bipyramids and T O 4 ( T = P, As) tetrahedra forming zig-zag sheets parallel to {0 1 0}. Sheets...

... − , O 2− , (Cl − ). The structure is characterized by six-membered tetrahedral rings ( T sites), whose apical oxygens point toward the (–) c-pole, producing the acentric nature of the structure. These planar rings of tetrahedra are linked by two types of octahedra, Z and Y, which share edges...