The crystalch emistry and crystal structure of naturalky anite crystals from the Eclogitic Micaschists Complex of the Sesia-Lanzo Zone, Western Italian Alps, have been investigated by means of optical microscopy, wavelength dispersive X-ray microanalysis, and single-crystal X-ray diffraction. The association of kyanite + garnet + phengitic-mica + chloritoid suggests that the eclogite-facies stages occurred at P ≤ 2.1 GPa and T ≤ 650ºC. Kyanite grains are large (cm-sized) porphyroblasts grown dynamically during one of the deformational events related to the subduction of the Austroalpine continentalcr ust. Under the polarizing microscope, kyanite grains show almost homogeneous cores, whereas rims are sometimes symplectitic aggregates of quartz and kyanite, confirming at least two stages of growth most likely related to the multistage deformational history of these rocks. Chemical analysis shows that Fe3+ is the major substituting cation for Al3+, ranging between 0.038 and 0.067 a.p.f.u.

The single-crystal X-ray diffraction investigation of the kyanites shows severely textured patterns on the (h0l)*-plane. Such evidence is not observed in the unwarped diffraction patterns on (0kl)* and (hk0)*. The most significant difference between the structuralp arameters refined in this study, with respect to those of previously published unstrained gem-quality crystals, concerns the displacement parameters. The anisotropic displacement ellipsoids of all the atomic sites are significantly larger than those previously described, and systematically oriented with the largest elliptical section almost perpendicular to [010]. The larger ellipsoids in the kyanite crystal investigated here reflect the displacement of the centre of gravity of the electron distribution, rather than an anomalous atomic thermal motion. The magnitude and orientation of the displacement parameters and the textured/strained diffraction pattern may be the result of two combined effects: (1) that the kyanite crystals are actually composed of several blocks; (2) the crystals are affected by a pervasive residual strain, as a result of tectonometamorphic plastic deformations and re-crystallization.

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.

Sector zoning in solid solutions of Tutton’s salts (NH4)2M(SO4)2.6H2O (M = Co, Ni, Zn, Mg) and nitrates of divalent metals Me(NO3)2 (Me = Sr, Pb, Ba) grown from low-T aqueous solutions under controlled conditions is studied. The effect of crystal composition and growth rate (supersaturation) on the intersector difference in concentrations of isomorphic components is examined experimentally and modelled theoretically based on the phenomenological approach to crystallization in a ‘solid solution—aqueous solution’ system. Calculations show a predominating contribution of the selective adsorption phenomena in the formation of a sector-zoned crystal with usually minor, but sometimes a major contribution of growth kinetics.

This paper reports an infrared spectroscopic study of a set of sodalite-group minerals. The specimens have been identified using a combination of X-ray diffraction and microchemical analysis. As expected, the Si/Al ratio is ~1; the extra framework cation content is characterized by a well-defined Na ⇌ (Ca+K) substitution. The lattice parameters of the studied samples range from sodalite (sample LM11) with a = 8.889(2) Å, to haüyne (sample HR3S) with a = 9.1265(2) Å. The specimens, having the SO2– group as a dominant anion, show a clear correlation between the a cell edge and the K content. Singlecrystal FTIR spectroscopy shows that haüyne and nosean typically contain enclathrated CO2 molecules, inadditionto H2O and minor carbonate, while sodalite is virtually CO2-free. Detailed microspectrometric mappings show a non-homogeneous distribution of volatile constituents across the crystals, which may be related to the presence of fractures in the crystals. Because of such zoning, a relatively wide variation is observed when calibrating extinction coefficients on the basis of a bulk analytical method such as CHN elemental analysis.

Zigrasite, ideally MgZr(PO4)2(H2O)4, is a new secondary phosphate mineral from the giant 1972 gem tourmaline-bearing pocket at the Dunton Quarry, Newry, Oxford County, Maine, USA. It occurs as subhedral blocky grains sometimes exceeding 1 mm in maximum dimension and perched on tourmaline. These grains are complex aggregates ofthree distinct phases, zigrasite and two unnamed phases: the Ca analogue of zigrasite, CaZr(PO4)2(H2O)4, and Zr(PO3OH)2(H2O)4. Zigrasite is associated with tourmaline, microcline, quartz, albite, beryl, amblygonite-montebrasite, childreniteeosphorite and apatite, and crystallized as one of the latest minerals during pocket formation. It is offwhite to pale yellow or light tan, translucent with a white streak and a vitreous lustre, and shows light blue to pale yellow cathodoluminescence. Mohs hardness is 3 and the measured and calculated densities are 2.76(4) and 2.66 g/cm3. The mineral has imperfect cleavage in two directions, parallel to (010) and (001), shows no parting, is brittle and has a hackly fracture. In transmitted light, it is colourless and non-pleochroic, biaxial negative with α 1.597(1), β 1.622 (1), γ 1.635 (1), with 2V(meas) = 65.5(4)º and 2V(calc.) = 71º. Zigrasite is triclinic, P , a 5.3049(2) Å, b 9.3372(4) Å, c 9.6282(5) Å, α 97.348(1)º, β 91.534(1)º, γ 90.512(4)º, V 472.79(5) Å3, Z = 2. The seven strongest lines in the X-ray powder diffraction pattern are as follows: d (Ê), I, (hkl): 9.550, 100, (001); 4.108, 70, ; 4.008, 50, (111); 4.589, 40, (110); 3.177, 40, (112); 3.569, 30, (0 2), 2.660, 30, (200),(11),(130); 3.273, 20, (12). Chemical analysis by electron microprobe gave P2O5 37.59, ZrO2 32.27, HfO2 0.34, FeO 0.20, MgO 10.37, ZnO 0.17, F 0.13, LOI 18.60, less O:F 0.05 = total 99.62 wt.%. The resulting empirical formula is (–)Σ=0.99(Zr0.99Hf0.01)Σ=1.00 P2.00O8(H2O)4 on the basis of12 O atoms with H2O = 4 per formula unit from crystal-structure analysis, and the end-member formula is MgZr(PO4)2(H2O)4.

The dehydration of pure and waste gypsums has been examined using in situ synchrotron angledispersive X-ray diffraction. Pure gypsum was studied under a number of defined environments; various industrial waste gypsums were also studied under a common standard environment. It is found that the dehydration of gypsum to anhydrite proceeds via the hemihydrate and γ-anhydrite phases and the interplay and behaviour of these phases has been determined by full structural ‘Rietveld’ refinement. In the study of the pure gypsum system, the hemihydrate structure is shown to be preserved as water is lost. A ‘zero-water hemihydrate’ is observed before refinement in the higher symmetry γ-anhydrite cell is possible. The waste gypsum materials studied showed significant differences in the temperatures at which key transformation events occurred; these observations raise implications concerning the re-use of by-product gypsum materials. Finally, high temperature data are re-examined in the search for a variation of the anhydrite structure.

The chemical composition oft he natural arsenate-apatite mineral johnbaumite [nominally Ca10(AsO4)6(OH)2] and its alteration product hedyphane [Ca4Pb6(AsO4)6Cl2] have been determined by electron microprobe analysis and the structures ofjohnbaumite and synthetic Sr-, Ba- and Pbarsenate apatites have been studied by As K-edge X-ray absorption spectroscopy and synchrotron X-ray powder diffraction. All samples belong to the holosymmetric apatite space group P63/m with As5+ substituted for P5+ in the tetrahedral structural site. Johnbaumite contains small amounts ofF and Pb (~0.9 and ~4.4 wt.% respectively) and hedyphane has the ideal composition (formula given above); the compositions of these coexisting phases define the two limbs ofa solvus occurring between Ca- and Pb-arsenate apatite end members. The unit-cell parameters and cation–oxygen bond lengths for the arsenate apatites studied are discussed alongside published data for end-member Ca-, Sr-, Ba- and Pbphosphate apatite analogues with (OH), F, Cl or Br as the anions at the centres of the channels in the apatite structure. This discussion rationalizes the relationships between the two structural sites A(1) and A(2) occupied by divalent cations in terms of the size of the A–O polyhedra and the distortion of the A(1)–O polyhedron as measured by the metaprism twist angle [O(1)–A(1)–O(2) projected onto (001)].

Two mineralogically distinct lamproites occurring as dykes in the Raniganj coalfield of eastern India are described in terms of a mineralogical-genetic classification as: (1) peralkaline olivine-ilmenitephlogopite- K-feldspar lamproite (var. Damodar); and (2) peralkaline pseudoleucite-phlogopite-amphibole- K-feldspar lamproite (var. Damodar). Compositional and paragenetic data are provided for major, accessory and trace minerals. Minerals common to both rocks include: chlorite-pseudomorphed phenocrystal olivine, phenocrystal Ti-rich Al-poor phlogopite and tetraferriphlogopite, groundmass potassic amphiboles, Sr-rich apatite and monazite-(Ce), late stage Na-poor K-feldspar and quartz. The rocks differ in terms of the character of the amphiboles (Ti-potassian arfvedsonite vs. K-richterite– K-magnesioarfvedsonite–K-arfvedsonite solid solution), spinel compositions (qandilite–chromite– magnetite vs. chromite–ulvöspinel–magnetite), the presence or absence of: pseudoleucite, microphenocrystal magnesian ilmenite, diopside, titanian aegirine, lorenzenite, an unamed Ti-silicate, an unnamed Mg-Zr silicate, bazirite, rutile, dolomite and norsethite. The rocks are considered to be members of a spectrum of modally-diverse peralkaline rocks, formed from a common parental magma produced by the partial melting of the ancient metasomatized lithospheric mantle of the northern Singhbhum craton. None of the rocks can be considered as aillikites, minettes, orangeites or kimberlites.

The equation of state of δ-AlOOH was investigated using powder X-ray diffraction up to 17 GPa. Measurement of the volume at 300 K gave a value of the bulk modulus of K0 = 124(2) GPa, whereas its pressure derivative was K’ = 13.5(7). The b axis of the unit cell is more compressible than the a and c axes – in agreement with a neutron diffraction study at high pressure by Sano-Furukawa et al. (2008). Measurements presented here show that δ-AlOOH has a compressibility 200% higher than in the previously reported equation of state by Vanpeteghem et al. (2002).

Fluoro-sodic-ferropedrizite, ideally ANaBLi2C()TSi8O22WF2, is a new mineral of the amphibole group from the Sutlug River, Tuva Republic, Russia. It occurs at the endogenic contact of a Li-pegmatite with country rocks near to a diabase dyke and formed by reaction of the pegmatitic melt with the country rock. Fluoro-sodic-ferropedrizite occurs as prismatic to acicular crystals, ranging in length from 0.1–3 cm and widths of up to 50 μm. Crystals occur inparallel to sub-parallel aggregates up to 5 mm across ina matrix of calcite and plagioclase feldspar. Crystals are pale bluish-grey with a greyish-white streak.

Fluoro-sodic-ferropedrizite is brittle, has a Mohs hardness of ~6 and a splintery fracture; it is non-fluorescent with perfect {110} cleavage, no observable parting, and has a calculated density of 3.116 g cm–3. In plane-polarized light, it is pleochroic, X = pale purple-grey, Y = light grey, Z = colourless; X ^ a = 71.2º (in β acute), Y || b, Z ^ c = 83.4º (in β obtuse). Fluoro-sodic-ferropedrizite is biaxial positive, α = 1.642(1), β = 1.644(1), γ = 1.652(1); 2V(obs) = 68.0(3)º, 2V(calc) = 56.4º. Fluoro-sodic-ferropedrizite is monoclinic, space group C2/m, a = 9.3720(4) Å, b = 17.6312(8) Å, c = 5.2732(3) Å, β = 102.247(4)º, V = 851.5(2) Å3, Z = 2. The strongest ten X-ray diffraction lines in the powder patternare (d in Å ,(I),(hkl)): 8.146,(10),(110); 2.686,(9),(151); 3.008,(8),(310); 4.430,(7),(021); 2.485,(6),(02); 3.383,(4),(131); 2.876,(3),(51, 11); 2.199,(3),(12); 4.030,(2),(111) and 3.795,(2),(31). Analysis by a combination of electron microprobe and crystal-structure refinement gives SiO2 59.81, Al2O3 12.66, TiO2 0.09, FeO 10.32, MgO 5.56, MnO 0.73, ZnO 0.17, CaO 0.20, Na2O 2.81, Li2O 4.80, F 2.43, H2Ocalc 1.10, sum = 99.65 wt.%. The formula unit, calculated on the basis of 24(O,OH,F) is A(Na0.68)B(Li1.92Na0.05Ca0.03)C() T(Si7.98Al0.02)O22W(F1.03OH0.97). Crystal-structure refinement shows Li to be completely ordered at the M(3) and M(4) sites. Fluoro-sodic-ferropedrizite, ideally ANaBLi2C()TSi8O22WF2, is related to the theoretical end-member ‘sodic-pedrizite’, ANaBLi2C(Mg2Al2Li)TSi8O22W(OH)2, by the substitutions CFe2+ → CMg and WF → W(OH).

Uraniferous particles from contaminated environmental samples were analysed by scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDXA) and microfocus extended X-ray absorption fine structure (mEXAFS) spectroscopy. The particles of interest are uranium oxides, which were released into the environment by the combustion of scrap depleted uranium (DU) metal at a factory in Colonie, New York, USA. Most of the identified particles appear to have primary, ‘as emitted’ morphologies; some have evidence of minor dissolution, including corrosion pitting. Polycrystalline and often hollow microscopic spheres were identified, which are similar to particles produced by DU munitions impacting armoured targets. They are attributed to the autothermic oxidation of melt droplets. The compositions of the analysed spheres are dominated by UO2+x with variable amounts of U3O8, two of the least soluble and least bioaccessible phases of U. These particles, collected from dusts and soils, have survived more than 25 y in the terrestrial environment. This study further supports the case for using Colonie as an analogue for battlefield DU contamination.