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The new mineral n&ouml, ggerathite-(Ce) was discovered in a sanidinite volcanic ejectum from the Laach Lake (Laacher See) paleovolcano in the Eifel region, Rhineland-Palatinate, Germany. Associated minerals are sanidine, dark mica, magnetite, baddeleyite, nosean, and a chevkinite-group mineral. N&ouml, ggerathite-(Ce) has a color that ranges from brown to deep brownish red, with adamantine luster, the streak is brownish red. It occurs in cavities of sanidinite and forms long prismatic crystals measuring up to 0.02 &times, 0.03 &times, 1.0 mm, with twins and random intergrowths. Its density calculated using the empirical formula is 5.332 g/cm3. The Vickers hardness number (VHN) is 615 kgf/mm2, which corresponds to a Mohs&rsquo, hardness of 5&frac12, The mean refractive index calculated using the Gladstone&ndash, Dale equation is 2.267. The Raman spectrum shows the absence of hydrogen-bearing groups. The chemical composition (electron microprobe holotype/cotype in wt %) is as follows: CaO 5.45/5.29, MnO 4.19/4.16, FeO 7.63/6.62, Al2O3 0.27/0.59, Y2O3 0.00/0.90, La2O3 3.17/3.64, Ce2O3 11.48/11.22, Pr2O3 1.04/0.92, Nd2O3 2.18/2.46, ThO2 2.32/1.98, TiO2 17.78/18.69, ZrO2 27.01/27.69, Nb2O5 17.04/15.77, total 99.59/99.82, respectively. The empirical formulae based on 14 O atoms per formula unit (apfu) are: (Ce0.59La0.165Nd0.11Pr0.05)&Sigma, 0.915Ca0.82Th0.07Mn0.50Fe0.90Al0.045Zr1.86Ti1.88Nb1.07O14 (holotype), and (Ce0.57La0.19Nd0.12Pr0.05Y0.06)&Sigma, 0.99Ca0.79Th0.06Mn0.49Fe0.77Al0.10Zr1.89Ti1.96Nb1.00O14 (cotype). The simplified formula is (Ce,Ca)2Zr2(Nb,Ti)(Ti,Nb)2Fe2+O14. N&ouml, ggerathite-(Ce) is orthorhombic, of the space group Cmca. The unit cell parameters are: a = 7.2985(3), b = 14.1454(4), c = 10.1607(4) &Aring, and V = 1048.99(7) &Aring, 3. The crystal structure was solved using single-crystal X-ray diffraction data. N&ouml, ggerathite-(Ce) is an analogue of zirconolite-3O, ideally CaZrTi2O7, with Nb dominant over Ti in one of two octahedral sites and REE dominant over Ca in the eight-fold coordinated site. The strongest lines of the powder X-ray diffraction pattern (d, &Aring, (I, %) (hkl)) are: 2.963 (91) (202), 2.903 (100) (042), 2.540 (39) (004), 1.823 (15) (400), 1.796 (51) (244), 1.543 (20) (442), and 1.519 (16) (282), respectively. The type material is deposited in the collections of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia (registration number 5123/1).

The crystal structure of TlOH was solved by direct methods: monoclinic, space group C121, a = 5.949(2), b = 6.220(2), c = 21.232(6) angstrom, beta = 91.590(5)degrees, V = 785.3(4) angstrom(3), R(1) = 0.075 for 439 unique reflecTlons with vertical bar F(o)vertical bar > 4 sigma(F). There are four symmetrically independent Tl(+) caTlons and four oxygen atoms of OH(-) groups in the structure. Each of the OH(-) groups forms three short Tl(+)-O bonds thus forming OHTl(3) triangles, which, in turn, share common edges to form [OH(2)Tl(4)](2+) dimeric groups. These hydroxocentercd units are interconnected with each other through common corners into layers. The layers are posiTloned so that hydrogen bonds are formed between two OH anionic planes. The structure of TlOH is significantly more complicated than those of the AOH (A = Na, K, Rb, Cs) hydroxides. The appearance of such complexity is induced by the presence of the stereochemically acTlve lone electron pair on the Tl(+) caTlons. Structural distorTlons occur in order to minimize destabilizing interacTlons. The stacking sequence in layered AOH hydroxides may involve one (KOH, RbOH), two (NaOH, CsOH) and four (TlOH) layers per unit cell. This feature may be considered as a special case of chemically induced polytypism.

A series of pyrochlores A(Nb,Ta)(2)(O,OH,F)(6)(nH(2)O), (A = NH(4), K, Rb, Cs) have been synthesized by hydrolysis of aqueous solutions of oxofluoroniobic (H(2)NbOF(5)) and fluorotantalic (H(2)TaF(7)) acids. This new method allows preparation of nanocrystalline niobate pyrochlores (crystal size 10-20 nm) by simple precipitation with subsequent boiling; tantalate analogues can be obtained by soft hydrothermal treatment. The synthesized compounds include new pyrochlores NH(4)Nb(2)O(5)(OH,F), NH(4)Ta(2)O(5)(OH,F)center dot nH(2)O and K(1-x)Nb(2)(O,OH)(5)F center dot nH(2)O as well as the already known CsNb(2)O(5)F, Rb(1-x)Nb(2)(O,OH)(5)F, CsTa(2)O(5)F and their hydroxyl analogues. Ion-exchange experiments revealed that K(0.7)Nb(2)(O,OH)(5)F center dot nH(2)O exhibits strong selective uptake of Pb(2+) from aqueous solutions, a feature not previously reported for pyrochlores. The facilitating role of fluoride ions in the synthesis of pyrochlores is discussed in comparison with zeolite synthesis, and the technological applicability of the new method is also presented in the paper.

The new thallium hydroxocarbonate Tl4(OH)2CO3 has been obtained by evaporation from aqueous solution. The crystal structure of the compound has been solved by direct methods: orthorhombic, Cmc21, a = 8.9963(18), b = 12.1500(30), c = 7.9542(15) Å, V = 869.43(3) Å3, R 1 = 0.056 for 763 unique reflections with |F o| ≥ 4σ F. There are three symmetrically independent Tl+ cations in the structure. The O atoms of the OH- groups are triangularly coordinated by three Tl atoms that results in formation of OHTl3 triangles with the O atom located at approx. 1.00 Å above the Tl3 plane. The OH- centered units are connected via common edges into [OH2Tl4]2+ dimers linked into chains through Tl–O bonds to CO3 groups. The structure contains channels parallel to the c axis. The formation of the lone pair cavity causes repulsion of Tl+ cations across these cavities and, as a consequence, distortion of the Tl+ cation arrangement.

Alumoåkermanite, (Ca,Na)2(Al,Mg,Fe2+)(Si2O7), is a new mineral member of the melilite group from the active carbonatite-nephelinite-phonolite volcano Oldoinyo Lengai, Tanzania. The mineral occurs as tabular phenocrysts and microphenocrysts in melilite-nephelinitic ashes and lapilli-tuffs. Alumoåkermanite is light brown in colour; it is transparent, with a vitreous lustre and the streak is white. Cleavages or partings are not observed. The mineral is brittle with an uneven fracture. The measured density is 2.96(2) g/cm3. The Mohs hardness is ~4.5–6. Alumoåkermanite is uniaxial (–) with ω = 1.635(1) and ε = 1.624–1.626(1). In a 30 mm thin section (+N), the mineral has a yellow to orange interference colour, straight extinction and positive elongation, and is nonpleochroic. The average chemical formula of the mineral derived from electron microprobe analyses is: (Ca1.48Na0.50Sr0.02 K0.01)(Si1.99Al0.01O7). Alumoåkermanite is tetragonal, space group P421m with a = 7.7661(4) Å, c = 5.0297(4) Å, V = 303.4(1) Å3 and Z = 2. The five strongest powder-diffraction lines [d in Å, (I/Io), hkl] are: 3.712, (13), (111); 3.075, (25), (201); 2.859, (100), (211); 2.456, (32), (311); 1.757, (19), (312). Single-crystal structure refinement (R1 = 0.018) revealed structure topology typical of the melilite-group minerals, i.e. tetrahedral [(Al,Mg)(Si2O7)] sheets interleaved with layers of (CaNa) cations. The name reflects the chemical composition of the mineral.

Armbrusterite, ideally K 5 Na 6 Mn 3+ Mn 14 2+ [Si 9 O 22 ] 4 (OH) 10 ·4H 2 O, is a new silicate of potassium, sodium, and manganese found in a thin cancrinite-aegirine-microcline vein within urtite at Mt. Kukisvumchorr. The mineral occurs in intimate association with raite. Other associated minerals are lamprophyllite, mangan-neptunite, pectolite, vinogradovite, calcite, molybdenite, galena, sphalerite, and fluorite. Armbrusterite occurs as split, curved crystals and spherulites (≤2 mm diameter). The mineral is translucent (transparent in thin fragments), dark reddish-brown. It has vitreous luster and light-brown streak. Cleavage is perfect on (001) and the fracture is uneven. Mohs hardness is about 3.5. In transmitted light, the mineral is reddish-brown, with strong pleochroism: X = light yellowish-brown, Y and Z = dark reddish-brown; dispersion r > v , weak. Armbrusterite is biaxial (−): α = 1.532(2), β = 1.560(2), γ = 1.564(2) (for λ = 589 nm), 2 V varies from 10° to 20°. Optical orientation: X is perpendicular to (001). The mean chemical composition determined by electron microprobe and the Penfield method (for H 2 O) is (wt%): Na 2 O 5.26, MgO 0.19, Al 2 O 3 0.04, SiO 2 56.02, K 2 O 6.13, CaO 0.26, TiO 2 0.04, MnO 23.62, Mn 2 O 3 2.07, FeO 0.65, ZnO 0.20, H 2 O 4.1, sum. 98.58. Empirical formula calculated on the basis of Si = 36 is K 5.03 Na 6.55 (Mn 12.86 2+ Mn 1.01 3+ Fe 0.35 2+ Mg 0.18 Ca 0.18 Zn 0.09 Al 0.03 Ti 0.02 ) ∑ =14.72 [Si 36 O 88 ](OH) 10.10 ·3.75 H 2 O. Armbrusterite is monoclinic, C 2/ m , a = 17.333(2), b = 23.539(3), c = 13.4895(17) A, β = 115.069(9)°, V = 4985.4(11) A 3 , Z = 2. The strongest X-ray powder-diffraction lines are [ d in A, (I), ( hkl )]: 12.28 (100) (001), 4.10 (10) (003), 3.562 (10) (113, 261), 3.260 (18) (114), 3.117 (13) (203), 3.077 (54) (004), 2.622 (10) (371). The crystal structure of armbrusterite was refined to R 1 = 0.085 on the basis of 3960 unique observed reflections. The structure is based upon double silicate [Si 9 O 22 ] layers consisting of 5-, 6-, 7-, and 8-membered tetrahedra rings. The layers are linked via octahedral sheets formed by Na and Mn octahedra. The interior of the double silicate layers is occupied by K + cations and H 2 O molecules. The mineral is named in honor of Thomas Armbruster (b. 1950; University of Berne) for his outstanding contribution to structural mineralogy and crystallography, especially to the study of Mn-rich minerals.

Niksergievite, [Ba 1.33 Ca 0.67 Al(CO 3 )(OH) 4 ][Al 2 (AlSi 3 O 10 )(OH) 2 ]• n H 2 O, is a new phyllosilicate closely related to the surite-ferrisurite series. It was found at the −400 m level of the Tekeli Pb-Zn mine, southeast Kazakhstan (44° N, 78° E). The mineral occurs as curved plates 3–5 mm in size forming rosette-like aggregates up to 5 cm across. Associated minerals include calcite, quartz, dolomite, celsian, sphalerite, pyrite, barite, and montmorillonite. Niksergievite is white with a light greenish tint and pearly luster on cleavage planes. The streak is white and the mineral is non-fluorescent. The Mohs hardness is 1–1½. The cleavage is perfect (mica-like) on {001}. D m = 3.16 g/cm 3 and D x = 3.21 g/cm 3 . The IR spectrum shows the following peaks (* shoulder): 3665*, 3640, 3405, 1630, 1454, 1105*, 1080*, 1035, 1020*, 980*, 960*, 920*, 876, 835*, 750*, 704, 625*, 560*, 535, 474, and 417 cm −1 . Optically, the mineral is colorless, non-pleochroic, biaxial (–), 2 V = 0–10°, α= 1.580(2), β= 1.625(2), γ = 1.625(2), and X ~ c . The chemical composition (electron microprobe, CO 2 and H 2 O by TGA) is K 2 O 0.1, CaO 5.1, BaO 27.1, MgO 0.4, FeO 0.2, Al 2 O 3 24.8, SiO 2 28.7, CO 2 6.1, and H 2 O 8.3, with a total of 100.8 wt%. The empirical formula based on (Si + Al + Mg + Fe 2+ ) = 7 is (Ba 1.27 Ca 0.65 K 0.02 ) 1.92 (Al 3.49 Si 3.42 Mg 0.07 Fe 0.02 ) 7.00 O 10.00 (CO 3 ) 0.99 (OH) 6.20 •0.20H 2 O. The simplified formula is (Ba,Ca) 2 (Al,Si) 7 O 10 (CO 3 )(OH) 6 • n H 2 O and the proposed structural formula is [Ba 1.33 Ca 0.67 Al(CO 3 )(OH) 4 ][Al 2 (AlSi 3 O 10 )(OH) 2 ]• n H 2 O. The mineral is monoclinic, C 2/ c , C 2, or Cm , a 5.176(3), b 8.989(3), c 16.166(5) A, β 96.44(6)°, V 747.4(9) A 3 , Z = 2. The strongest reflections in the X-ray powder diffraction pattern are as follows [ d in A, ( I ) ( hkl )]: 16.1(40)(001), 4.49(90)(020), 3.68(60)(014,113), 2.585(100)(130, 201, 131), 2.230(90)(134,220), 2.069(80)(043), 1.692(60)( 311, 151,240). It is named in honor of Prof. Nikolai Grigorievich Sergiev (1901–1960) for his contributions to the geology of Kazakhstan.

Filatovite, ideally K((Al,Zn)2(As,Si)2O8), has been found in products of fumarolic activity on the second cinder cone of the North breach of the great fissure Tolbachik eruption (1975-76, Kamchatka peninsula, Russia). The mineral occurs as pris- matic crystals up to 0.3 mm and as intergrowths of crystals, in association with alumoklyuchevskite, lammerite, johillerite, sylvite, As-bearing orthoclase, hematite and tenorite. Filatovite is colourless, with vitreous luster and white streak. The mineral is brittle and transparent. It has a good {100} cleavage. Mohs' hardness is 5-6. The calculated density is 2.92 g/cm3. Biaxial, optically nega- tive, ! = 1.532(1), " = 1.535(1), # = 1.537(1), 2Vmeas. = 60(10)°, 2Vcalc. = 78°. Optical orientation: X ~ (100), Y and Z are normal to the {001} and {010} faces, respectively. No pleochroism has been observed. The mineral is monoclinic, space group I2/c, a = 8.772(1), b = 13.370(2), c = 14.690(2) A, " = 115.944(6)°, V = 1549.1(4) A3, Z = 8 (from single-crystal structure study). The diagnostic lines of the X-ray powder diffraction pattern are (I-d-hkl): 70-4.329- $ 202; 70-3.897- $ 130; 100-3.364- $ 220,$ 204, 040; 50-3.300-004, 40-3.066-132, 60-2.981-042, 40-2.646- $ 242. Chemical composition (wt. %): P2O5 1.63, As2O5 40.60, SiO2 12.35, Al2O3 27.33, CuO 0.83, ZnO 3.85, FeO 0.28, Na2O 0.63, K2O 12.85, total 100.35. The empirical formula of filatovite, calculated on the basis of O = 8, is (K0.92Na0.07)% =0.99((Al1.81Zn0.16Cu0.04Fe0.01)% =2.02(As1.20Si0.70P0.08)% =1.98O8). The simplified formula is K((Al,Zn)2(As,Si)2O8). The detailed chemical formula can be written as K((Al2-xZnx)(As1+xSi1-x)O8), with x ~ 0.20. Filatovite is a new mineral of the feldspar group and is structurally related to celsian. The name honors Prof. Stanislav K. Filatov (b. 1940), Department of Crystallography, St. Petersburg State University, St. Petersburg, Russia, for his important contributions to high temperature crystal chemistry and crystal chemistry of exhalation minerals.

Fluorvesuvianite was found in the abandoned Lupikko iron mine, Pitkaranta, Karelia, Russia. It occurs in cavities of chloritized diopside skarn, as radiating aggregates of acicular crystals in calcite. Crystals (up to 1.5 cm long and 5-20 mum across) are elongate along [001]; the dominant forms are {100} or {110}. Associated minerals are sphalerite and clinochlore. Single crystals of fluorvesuvianite are colorless and transparent, aggregates are white with silky luster, and the mineral is non-fluorescent. The Mohs hardness is 6. The mineral is brittle, and no cleavage or parting was observed. D-meas is 3.46(3) g/cm(3), and D-calc is 3.43 g/cm(3). In immersion liquids, the mineral is colorless and non-pleochroic. Fluorvesuvianite is uniaxial (-), omega 1.702(1), epsilon 1.699(1) for lambda = 589 nm. Chemical composition (electron microprobe, H2O by TGA, F by ion-selective electrode., wt.%): CaO 36.1, MgO 1.9, MnO 0.1, FeO 2.8, Al2O3 17.9, SiO2 36.6, H2O 0.5, F 4.6, -O=2F 1.94, Total 98.56. The empirical formula based on 50 cations per formula unit is Ca-19.03 (Al10.38Mg1.39Fe1.152+Mn0.042+)(Sigma12.96) Si18.01O68.00 (F7.16OH1.64O0.80)(Sigma9.60), which corresponds to the ideal formula Ca-19 (Al,Mg,Fe2+)(13) [SiO4](10) [Si2O7](4) O(F,OH)(9). The bands in the IR spectrum are: 3625, 3555, 3400, 3170, 1650, 1575, 1080 shoulder, 1021, 983, 905, 870 shoulder, 800, 710 shoulder, 636, 605, 577, 490, 444, 411, 395 cm(-1). The strongest eight lines in the X-ray powder-diffraction pattern [d in Angstrom(I)(hkl)] are: 4.74(20)(202), 3.465(30)(420), 3.040(30)(510), 2.945(35)(004), 2.743(90)(432,440), 2.589(50)(224,522), 2.453(100)(620), and 1.619(30)(526,922). Fluorvesuvianite is tetragonal, space group P4/nnc, unit-cell parameters refined from the powder data: a 15.516(2), c 11.772(3)Angstrom, V 2834(1)Angstrom(3), Z = 2. The crystal structure has been refined to R-1 = 0.043, calculated for 1108 unique observed reflection (\F-o\ greater than or equal to 4sigma \F-o\). The structure refinement demonstrates that most of the fluorine is at the F(11) position [the refined site-occupancy is F-0.72(OH)(0.28)]. The elongate bond length (1.664 Angstrom) and the Si(1) site-occupancy factor, 0.803(8), suggest substitution according to the scheme (SiO4)(4-) 4F(-). If Ca-19 (Al,Mg,Fe2+)(13) [SiO4](10) [SiO7](4) O(OH)(9) is considered the formula of vesuvianite, the end-member composition of fluorvesuvianite is Ca-19(Al,Mg,Fe2+)(13)[SiO4](10)[Si2O7](4)O(F)(9). In other words. a vesuvianite-group specimen with more than 4.5 F apfu is named fluorvesuvianite.

Alkali-induced hydrolysis of fluoro-complexes of Ta and Nb affords one-pot synthesis of well crystallized compounds containing Lindqvist hexatantalate [Ta6O19]8 − and hexaniobate [Nb6O19]8 − ions. As an example, Na8Ta6O19·26H2O, a polyoxometalate with a remarkably complex layered structure was synthesized using the new method. An advantage of the proposed synthetic approach is that it can be easily embedded into existing technological flowcharts for the processing of Nb and Ta allowing direct synthesis of polyoxometalates from inexpensive fluoride precursors.

Allabogdanite, (Fe,Ni) 2 P, is a new mineral from the Onello iron meteorite (Ni-rich ataxite). It occurs as thin lamellar crystals disseminated in plessite. Associated minerals are nickelphosphide, schreibersite, awaruite, and graphite. Crystals of the mineral, up to 0.4 × 0.1 × 0.01 mm, are flattened on (001) with dominant {001} faces, and other faces that are probably {110} and {100}. Mirror twinning resembling that of gypsum is common, with possible twin composition plane {110}. Crystals are light straw-yellow with bright metallic luster. Polished (001) sections look silvery-white against an epoxy background. In reflected light in air, the mineral has a creamy color, with distinct anisotropy from light to dark creamy tint. No bireflectance was observed. R 1 /R2 (λ, nm) in air: 48.4/37.2(440), 46.7/36.8(460), 47.0/37.6(480), 47.5/38.1(500), 47.6/38.8(520), 48.2/39.2(540), 49.0/39.9(560), 49.6/40.7(580), 50.1/41.6(600), 50.5/41.9(620), 51.9/43.0(640), 52.3/44.3(660), 53.3/45.0(680), 54.4/46.2(700). No cleavage or parting was observed. Moh’s hardness is 5–6; the mineral is very brittle, and its calculated density 7.10 g/cm 3 . Its chemical composition (determined by microprobe methods, average of nine analyses) is: Fe 57.7, Ni 20.7, Co 1.4, P 20.4, Total 100.2 wt%, corresponding to (Fe 1.51 Ni 0.50 Co 0.03 ) 2.04 P 0.96 (three atoms per formula unit). Crystal structure: R 1 = 0.040 for 138 unique observed (| F o|≥ 4σ F ) reflections. Orthorhombic, Pnma , unit-cell parameters refined from powder data: a = 5.748(2), b = 3.548(1), c = 6.661(2) A, V = 135.8(1), A 3 , Z = 4; unit-cell parameters refined from single-crystal data: a = 5.792(7), b = 3.564(4), c = 6.691(8) A, and V = 138.1(3) A 3 . Strongest reflections in the X-ray powder diffraction pattern are [ d in A, ( I ) ( hkl )]: 2.238(100)(112), 2.120(80)(211), 2.073(70)(103), 1.884(50)(013), 1.843(40)(301), 1.788(40)(113), 1.774(40)(020). The mineral is named for Alla Bogdanova, Geological Institute, Kola Science Centre of Russian Academy of Sciences.

La burnsite, dont la formule ideale est KCdCu 7 O 2 (SeO 3 ) 2 Cl 9 , a ete decouverte dans une fumerolle dans la breche du Nord de la grande eruption fissurale du volcan Tolbachik (1975-1976), dans la peninsule de Kamchatka, en Russie. Elle se presente en grains rouge fonce, xenomorphes, equidimensionnels. Lui sont associes cotunnite, sophiite, chloromenite, georgbokiite, ilinskite et un selenite Cu-Pb non defini. La burnsite est consideree rarissime, n'ayant ete trouvee que dans quelques douzaines de grains qui ne depassent pas 0.1 mm. Elle ressemble beaucoup a la georgbokiite et au selenite de Cu-Pb non defini, mais s'en distingue par sa couleur rouge. La burnsite a un eclat fortement vitreux (metalloide) et une rayure rougeâtre. C'est un mineral cassant, opaque a translucide, avec une cassure inerale. Le clivage est bon le long du plan (001). La durete VHN est egale a 12 kg/mm 2 . La densite calculee est egale a 3.85 g/cm 3 . Elle est non fluorescente. La burnsite est uniaxe negative, E 1.912(5), O 1.920(5), avec une faible bireflectance et sans pleochroisme. Elle est hexagonale, groupe spatial P6 3 /mmc, a 8.7805(8), b 15.521(2) A, V 1036.3(2) A 3 , Z = 2. Les huit raies les plus intenses du spectre de diffraction. methode des poudres [d en A (I)(hkl)] sont: 7.779(100)(002), 6.823(50)(101), 4.391(60)(100), 3.814(80)(200), 3.066(70)(203), 2.582(50)(006), 2.501(60)(213) et 2.190(50)(220). Les analyses a la microsonde electronique ont donne K 2 O 4.30, CuO 46.74,CdO 10.45, SeO 2 19.91, Cl 25.46, moins O=Cl 2 -5.75, pour un total de 101.11% (poids). La formule empirique, derivee a partir de la determination de la structure et des donnees chimiques, est K 1 . 0 8 Cd 0 . 9 7 Cu 6 . 9 8 O 2 . 0 5 (Se 1 . 0 7 O 3 . 2 1 ) 2 Cl 8 . 5 3 sur une base de O + Cl = 17. Le nom choisi honore Peter C. Burns, professeur ;a l'Universite de Notre Dame, Indiana, pour souligner ses contributions importantes a la mineralogie structurale.

Cattiite, Mg 3(PO4)2·22H2O, is a new mineral from Zhelezny (Iron) Mine (Kovdor carbonatite massif, Kola Peninsula, Russia). It appears as crystalline mas- ses up to 1.5cm in size filling up cavities of dolomite carbonatite. Associated min- erals are dolomite, bakhchisaraitsevite, nastrophite, magnetite, sjogrenite and carbo- nate- fluorapatite. Rare {001} tabular crystals are observed within the masses. Co- lourless, transparent. Lustre vitreous with pearly sheen on cleavage fractures. Per- fect {001} cleavage. Brittle; Moh' s hardness 2. D(meas) 1.65(2) g/cm 3 , D(calc) 1.640(1) g/cm 3 . In immersion liquids cattiite is colourless and non-pleochroic. Bi

The crystal structure of rimkorolgite, ideally Ba[Mg 5 (H 2 O) 7 (PO 4 ) 4 ](H 2 O), (monoclinic, P 2 1 / c, a = 8.3354(9), b = 12.8304(13), c = 18.313(2) A, β = 90.025(2)°, V = 1958.5(4) A 3 , Z = 4) has been solved by direct methods and refined to R 1 = 0.052 using X-ray diffraction data collected from a crystal twinned on (001). There are five symmetrically independent Mg 2+ cations that are each octahedrally coordinated by four O atoms and two H 2 O groups. One symmetrically independent Ba 2+ cation is coordinated by eight O atoms and two H 2 O groups. The Mgϕ 6 octahedra (ϕ = O, H 2 O) and PO 4 tetrahedra form sheets parallel to (001). Their main elements are zigzag chains of the Mgϕ 6 edge-sharing octahedra. The chains are linked via common vertices to form an octahedral sheet in which Mg atoms are located at the vertices of the 6 3 hexagonal net. The PO 4 tetrahedra are above and below hexagonal rings of Mg octahedra and are linked to them by sharing common O vertices. The Ba atoms and H 2 O(1) and H 2 O(22) groups are located between the sheets providing their linkage into three-dimensional structure. The structure of rimkorolgite is closely related to that of bakhchisaraitsevite, Na 2 Mg 5 (PO 4 ) 4 7H 2 O. Both structures are based on the octahedral-tetrahedral sheets of the same type. In bakhchisaraitsevite, the sheets are linked into three-dimensional framework by edge-sharing between the Mgϕ 6 octahedra from two adjacent sheets, whereas in rimkorolgite, there is no linkage between adjacent sheets. The structure of rimkorolgite can be considered as bakhchisaraitsevite-like framework interrupted by the presence of large Ba 2+ cations.

Natural phosphides - the minerals containing phosphorus in a redox state lower than zero – are common constituents of meteorites but virtually unknown on the Earth. Herein we present the first rich occurrence of iron-nickel phosphides of terrestrial origin. Phosphide-bearing rocks are exposed in three localities in the surroundings of the Dead Sea, Levant: in the northern Negev Desert, Israel and Transjordan Plateau, south of Amman, Jordan. Seven minerals from the ternary Fe-Ni-P system have been identified with five of them, NiP2, Ni5P4, Ni2P, FeP and FeP2, previously unknown in nature. The results of the present study could provide a new insight on the terrestrial origin of natural phosphides – the most likely source of reactive prebiotic phosphorus at the times of the early Earth.

Alkali-induced hydrolysis of fluoro-complexes of Ta and Nb affords one-pot synthesis of well crystallized compounds containing Lindqvist hexatantalate [Ta6O19]8 − and hexaniobate [Nb6O19]8 − ions. As an example, Na8Ta6O19·26H2O, a polyoxometalate with a remarkably complex layered structure was synthesized using the new method. An advantage of the proposed synthetic approach is that it can be easily embedded into existing technological flowcharts for the processing of Nb and Ta allowing direct synthesis of polyoxometalates from inexpensive fluoride precursors.

Layered hydrazinium titanate LHT-9, (N2H5)1/2Ti1.87O4 is a new nanohybrid material related to lepidocrocite-type titanates. Unique combination of ion exchange, reductive properties, surface activity due to Brønsted acid sites and occurrence of surface titanyl groups allows exploring LHT-9 for simultaneous uptake of almost all components of liquid nuclear wastes. LHT-9 irreversibly removes technetium, molybdenum, palladium and selenium from their aqueous solutions by specific mechanism of reductive adsorption. For removal of cesium, strontium, transition elements, actinides and lanthanides LHT-9 provides mechanisms of ion exchange and surface complexation. Products of adsorption are nanocrystalline and homogeneous powders loaded with 5 to 15 wt. % of radionuclides and non-radioactive elements. LHT-9 can be applied as ready-to-use precursor for one-step synthesis of durable titanate ceramic waste forms similar to SYNROC. An essential advantage of LHT-9 in comparison with other titanate sorbents (monosodium titanate and peroxo-titanate materials) is the absence of Na in its composition that permits arbitrary tailoring of sorbent properties by simple pre-treatment with the desired elements. Results on sorption of americium, cesium, strontium and lanthanides by LHT-9 are discussed.

Titanosilicates have important applications in various areas of technology such as catalysis, gas separation, energy storage, optoelectronics, radioactive waste management, etc. Many of these materials are known as minerals, e.g. zorite Na6[Ti(Ti,Nb)4(Si6O17)2(O,OH)5].nH2O (n=10–11), a natural analogue of ETS-4 (Engelhard Titanium Silicate-4). The modified form of ETS-4, CTS-1 (contracted titanosilicate-1), is used for separation of mixtures of gases with similar molecular diameters, e.g. N2/O2 and CO/H2. Ba-exchanged ETS-4 is used for separation of mixtures of N2 and CH4. Another area of applications of ETS-4 and CTS-1 is purification of water polluted by organic contaminants. Natural Ca-bearing analogues of zorite are chivruaiite Ca4[(Ti,Nb)5(Si6O17)2|(OH,O)5].13-14H2O, and haineaultite, (Na,Ca)5Ca[(Ti,Nb)5(Si,S)12O34 (OH,F)8].5H2O.

Layered oxide compounds with structures based upon combinations of [TiO6] and [NbO6] octahedral building blocks attract considerable scientific and industrial interest due to their structural diversity and wide field for technological applications. The group of layered titanates is by far the best studied among this family of layered oxides (Bavykin et al. 2006; Doong and Kao 2008). In general, the crystal structures of layered titanates can be derived from the crystal structure of lepidocrocite, orthorhombic γ-FeOOH (England et al. 1983).

Orange prismatic crystals of the first thallium hydrous nesosilicate Tl(4)SiO(4)center dot 0.5H(2)O have been obtained by evaporation from aqueous Solution. There are three symmetrically independent Tl(+) cations and five symmetrically independent oxygen atoms in the structure of Tl(4)SiO(4)center dot 0.5H(2)O. The O(4) and O(5) atoms belong to water molecules. Coordination polyhedra of the Tl(+) cations are strongly distorted because of the stereoactive behavior of lone electron pairs. The structure of Tl(4)SiO(4)center dot 0.5H(2)O contains sheets of SiO(4) tetrahedra and Tl coordination polyhedra. The sheets have the composition [Tl(3)SiO(4)](-) and are parallel to [100]. Within the sheets, SiO(4) tetrahedra link to thallium polyhedra though common corners. The sheets are linked by dimers of face-sharing Tl(3)O(5) polyhedra. thus providing interconnection of the sheets into a framework. The framework has large elliptical channels occupied by water molecules (OW2) and electron pairs of Tl(+) cations. The comparison with some other M(+) (M = K, Ag, Tl) silicates is given.

Layered double hydroxides (LDH) — a wide family of compounds involving representatives of closely related mineral groups, including hydrotalcite-manasseite, quintinite, woodwardite, meixnerite and hydrocalumite-kuzelite groups, as well as their numerous synthetic analogues (Strunz and Nickel 2001, Rives 2001, Khan and O’Hare 2002). In the past decades, LDH attracted considerable attention due to their chemical and structural features applicable in different fields of industry. These compounds are easily synthesized in water solutions under ambient conditions. LDH adopt huge variety of cations inside hydroxide slabs, making possible easy preparation of oxide catalysts by simple heat treatment. But the most striking and useful peculiarity is their anion-exchange properties. Contrary to large number of cation-exchangers related to different classes of compounds, number of known anion-exchange frameworks is rather limited. Among them, LDH (also known as “anionic clays”) are quite unique because they may adopt and exchange tenths of different anions (Miyata and Kimura 1973, Miyata 1975, Miyata and Okada 1977, Rives 2001, Khan and O’Hare 2002, Kloprogge et al. 2002 and the references cited herein). As a consequence, they are widely used for selective extraction of anions, purification of solutions and preparation of different types of combined catalysts.

Within recent years, titanosilicates and other octahedral-tetrahedral framework materials have attracted considerable attention due to their applications in catalysis, gas separation, energy storage, optoelectronics, radioactive waste management, etc. (Behrens et al. 1998; Lamberti 1999; Rocha and Anderson 2000; Zecchina et al. 2001). Before being synthesized under laboratory conditions, many of these materials were known as minerals. Engelhard titanosilicate ETS-4, which is now used in gas industry on a multitonn scale (Kuznicki et al. 2001), is a synthetic analogue of zorite, a framework sodium titanosilicate described in 1970s from alkaline complexes of the Kola peninsula, Russia (Mer’kov et al. 1973; Sandomirskii and Belov 1979). This and many other examples show that investigations of minerals are not only of mineralogical interest but may also provide important ideas for synthesis of new materials with important industrial applications.

Sulfates and phosphates consisting of mixed anionic radicals (or heteropolyhedral units) constitute a large group of mineral species. In this contribution, we will summarize our recent results on some novel or poorly studied minerals, whose structures are based upon octahedral-tetrahedral structural units. During investigations of secondary pegmatite phosphates from Hagendorf (Germany), we have located a new whiteite-jahnsite-group mineral that was named whiteite-(CaMnMn) Its structure is formed by alternating anionic layers composed from MO6octahedra and PO4tetrahedra, and linked together thorugh M(2) cations and water molecules. The crystal structure of bonshtedtite, Na3Fe(PO4)(CO3), is similar to that of the other minerals of the bradleyite group. It is based upon the [Fe(PO4)(CO3)]3-layers oriented parallel to (001). Refinement of the crystal structure of girvasite at 110 K allowed to determine positions of H atoms and to reveal the hydrogen bonding scheme. The refinement confirmed that the proper chemical formula of the mineral should be written as NaCa2Mg3(PO4)4(CO3)(H2O)6, in contrast to the formula NaCa2Mg3(PO4)2[PO2(OH)2](CO3)(OH)2(H2O)4proposed in the original works. The crystal structure of cattiite, Mg3(PO4)2(H2O)22contains two symmetrically independent Mg sites, tetrahedrally coordinated by water molecules to form octahedral complexes [Mg(H2O)6]. The crystal structure of vendidaite, Al2(SO4)(OH)3Cl(H2O)6, contains one symmetrically independent Al site coordinated by three OH groups and three H2O molecules. Together with the [Al2(OH)3(H2O)6]3+chains, Cl- anions and (SO4)2-groups form pseudo-layers parallel to (010).Steklite, KAl(SO4)2, was first described as a technogenic phase in products of burning coal dumps (Chelyabinsk region, Russia). Steklite of natural origin was found in sublimates of the Yadovitaya (Poisonous) fumarole of the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Kamchatka, Russia.