Chalcopyrite samples from Mt Isa, Australia have been experimentally shortened by up to 30% at temperatures up to 450°C at a constant confining pressure of 300 (400) MPa, and different strain rates in the range from 10-5 to 10-8 sec-1. After deformation, the X-ray pole figures show a maximum of (220/204) perpendicular to the compression axis for each of the samples, which has already been described for room temperature experiments by Lang (1968). The overlapping pseudocubic peaks of chalcopyrite can be separated into true tetragonal peaks by neutron diffraction texture analysis using a position sensitive detector combined with profile analysis (Will et al., 1989). The five investigated samples each show a combination of two or four main orientations of the crystallites, which represent neither a pseudocubic nor a tetragonal fibre texture.

The crystal structure of zigrasite, ideally MgZr(PO4)2(H2O)4, a 5.3049(2), b 9.3372(4), c 9.6282(5) Å, α 97.348(1)°, β 91.534(1)°, γ 90.512(4)°, V 472.79(5) Å3, Z = 2, triclinic, P1, Dcalc. 2.66 g.cm–3, from the giant 1972 pocket at Newry, Oxford County, Maine, USA, has been solved and refined to R1 3.75% on the basis of 2623 unique reflections (Fo > 4σF). There are two P sites, each of which is solely occupied by P with <P–O> distances of 1.532 and 1.533 Å, respectively. There are two Mg sites, both of which are occupied by Mg and are octahedrally coordinated two O anions and four (H2O) groups with <Mg–O> distances of 2.064 and 2.075 Å, respectively. There is one Zr site, occupied by Zr and octahedrally coordinated by six O anions with a <Zr–O> distance of 2.065 Å . The (ZrO6) octahedron shares corners with six (PO4) tetrahedra, forminga [Zr(PO4)2] sheet parallel to (001). These sheets are stacked in the c direction and linked by (MgO2(H2O)4) octahedra that share O atoms with the (PO4) groups. The structure is formally a heteropolyhedral framework structure, but the linkage is weaker in the c direction, accounting for the marked (001) cleavage.

Wolframite-bearing quartz veins from Garganta de los Montes, Madrid province, are hosted by banded gneisses that have undergone intense migmatization processes. The ore deposit is closely related to the La Cabrera granitic batholith. The veins strike 075° and dip 75°S. The mineral association includes wolframite, quartz and minor amounts of scheelite and sulphides (sphalerite, chalcopyrite, pyrrhotite, stannite and marcasite). The fluid phases associated with quartz from the vein margin (early barren quartz) and from the vein centre (late wolframite-bearing quartz) have been studied using microthermometry, scanning electron microscopy and crushing test analyses. Four hydrothermal stages have been distinguished.

The earliest fluids, only recognized in the barren quartz, contain brine, daughter phase (halite) and trapped minerals. The second hydrothermal stage is characterized by complex carbonic-aqueous inclusions of low salinity (3 to 7 wt.% eq. NaC1) and low density (0.4 to 0.7 g.cm−3). They mainly homogenize into liquid between 300 and 420°C. The third stage is represented by low to moderate salinity inclusions (<9 wt. % eq. NaCl) of moderate density (0.8 to 0.96 g.cm−3), homogenizing between 120° and 330°C. The latest fluids correspond to aqueous solutions of higher salinities (H2O-NaCl, with Ca2+ and Mg2+) and densities (>1 g.cm−3), with TH ranging between 50 and 130°C. The role of the complex-carbonic aqueous fluids in the transport and precipitation of tungsten is highlighted.

Norilskite, (Pd,Ag)7Pb4 is a new platinum-group mineral discovered in the Mayak mine of the Talnakh deposit, Russia. It forms anhedral grains in aggregates (up to ∼400 μm) with polarite, zvyagintsevite, Pd-rich tetra-auricupride, Pd-Pt bearing auricupride,Ag-Au alloys, (Pb,As,Sb) bearing atokite, mayakite, Bi-Pb-rich kotulskite and sperrylite in pentlandite, cubanite and talnakhite. Norilskite is brittle, has a metallic lustre and a grey streak. Values of VHN20 fall between 296 and 342 kg mm–2, with a mean valueof 310 kg mm–2, corresponding to a Mohs hardness of ∼4. In plane-polarized light, norilskite is orange-brownish pink, has moderate to strong bireflectance, orange-pink to greyish-pink pleochroism, and strong anisotropy; it exhibits no internal reflections. Reflectancevalues of norilskite in air (Ro, Re' in %) are: 51.1, 48.8 at 470 nm, 56.8, 52.2 at 546 nm, 59.9, 53.5 at 589 nm and 64.7, 55.5 at 650 nm. Sixteen electronmicroprobe analyses of natural norilskite gave an average composition: Pd 44.33, Ag 2.68, Bi 0.33 and Pb 52.34, total99.68 wt.%, corresponding to the empirical formula (Pd6.56Ag0.39)∑6.95(Pb3.97Bi0.03)∑4.00 based on 4 Pb + Bi atoms; the average of eight analyses on synthetic norilskite is: Pd 42.95, Ag 3.87 and Pb 53.51, total 100.33wt.%, corresponding to (Pd6.25Ag0.56)∑6.81Pb4.00. The mineral is trigonal, space group P3121, with a = 8.9656(4), c = 17.2801(8) Å, V = 1202.92(9) Å3 and Z = 6. The crystalstructure was solved and refined from the powder X-ray diffraction data of synthetic (Pd,Ag)7Pb4. Norilskite crystallizes in the Ni13Ga3Ge6 structure type, related to nickeline. The strongest lines in the powder X-ray diffraction patternof synthetic norilskite [d in Å (I) (hkl)] are: 3.2201(29)(023,203), 2.3130(91)(026,206), 2.2414(100)(220), 1.6098(28)(046,406), 1.3076(38)(246,462), 1.2942(18)(600), 1.2115(37)(22.12,12.13), 0.9626(44) (06.12,60.12). The mineral is named for the locality, the Noril'sk district in Russia.

Some samples of hollandite-type titanates from the Murun alkaline complex (Yakutia, Russia) contain appreciable amounts of Pb (up to 12.5 wt.% PbO). These titanates occur in a pegmatitic K-feldsparaegirine rock containing subordinate K-rich batisite, titanite, wadeite and other minerals. The Pb-bearing crystals coexist with hollandite-type phases devoid of detectable Pb and zoned from a Kdominant (priderite) core to a Ba-dominant (henrymeyerite) rim. Recalculation of the microprobe analyses on the stoichiometric basis indicates that most of the Fe occurs in this mineral in trivalent form, suggesting the existence of a solid solution between the Ba(Ti6Fe)O16, K2(Ti6Fe)O16 and Pb(Ti6Fe)O16 end-members. The maximum proportion of the latter end-member in the Murun titanates is ∽45 mol.%. The Ba-free compositions [Pb1.0–1.3(Ti,Fe)8O16] and intermediate members of the (Ba1–xPbx)(Ti6Fe)O16 series were synthesized at 1050 –1100ºC. The synthesis products comprise tetragonal hollandites of various stoichiometry intermixed with rutile, a pseudobrookite-type phase and (for the Ba-free compositions) minor macedonite. Electron microprobe analyses of the hollandites indicate that there is a continuous series of compositions between the two hexatitanate end-members, Ba(Ti6Fe)O16 and Pb(Ti6Fe)O16. The crystal structure of one intermediate member was refined by the Rietveld method in space group I4/m, and found to differ from the hollandite archetype (i.e. Pb-bearing Ba manganate) in that Pb is preferentially partitioned into the 2b tunnel site at (0,0,½), whereas Ba is partitioned into the larger 4e site at (0,0,∽0.8).

The compositional zonation of both undeformed and plastically deformed tourmaline crystals from an amphibolite-facies mylonitic pegmatite from the Sierras Pampeanas (NW Argentina) has been investigated using electron microprobe analysis (EMPA). Undeformed tourmaline shows optical and compositional major and minor element growth zonation with a Ca- and Mg-rich rim zone and an Fe- rich core zone. The tourmaline population of the mylonite consists of crystals which appear undeformed at microscopic scale, and of weakly, moderately, and strongly deformed crystals. Depending on the intensity of plastic deformation, the optical zonation is blurred or absent, and the compositional zonation is less pronounced or destroyed. Plastic deformation mobilizes small cations (Fe2+, Mg2+) more efficiently and at lower deformation intensity than larger cations (Na+, Ca2+). In addition to intra-crystal homogenization, plastic deformation caused variable but generally minor Fe, Mg, Si, Al, Ca, and Na exchange between deformed tourmaline domains and co-existing fluid or solid phases. Dislocation creep is interpreted as the dominant deformation mechanism leading to the homogenization of the initial tourmaline growth zonation. The composition and the degree of homogeneity of deformed tourmaline domains depend on the initial composition of the growth zones, their initial volume ratio, the intensity and homogeneity of plastic deformation, and the size of the mobilized cation. Consequently, the composition of and the element distribution within plastically deformed crystals is not entirely controlled by intensive variables (P-T-X), and therefore not suitable for petrogenetic interpretation.

The crystal structure of mendeleevite-(Ce), (Cs,☐)6(☐,Cs)6(☐,K)6(REE,Ca,☐)6(Si70O175) (H2O,OH,F,D)35, a new mineral from the moraine of the Darai-Pioz glacier, the Alai mountain ridge. Tien-Shan mountains, northern Tajikistan, was solved by direct methods and refined to Ri = 4.15% based on 2274 observed [Fo > 4σ|F|] unique reflections measured with Mo-Kα. radiation on a Bruker PA diffractorneter equipped with a CCD detector. Mendeleevite-(Ce) is cubic, space group Pm3̄, a 21.9148(4) Å, V 10525(1) Å3, Z = 2, Dcalc = 3.066 g/cm3. The empirical formula (electron microprobe) is CS5.94K2.22[(Ce11.35La5.86Nd3.23Pr1.54Sm0.32Gd0.20)Σ22.50(Ca4.68Sr1.00)Σ5.68]Σ28.18 Si70.12O203.17H45.67F6.83, Z = 2, calculated on the basis of 210 (O + F) a.p.f.u., with H2O and OH calculated from structure refinement (OH + F = 17 p.f.u.; H2O = 17.75 p.f.u.).

The structural formula is (Cs4.65☐1.35)Σ6(☐4.71Cs1.29)Σ6(☐3.78K2.22)Σ6﹛[(Ce11.35La5.86Nd3.23 Pr1.54Sm0.32Gd0.20)Σ22.50(Ca4.68Sr1.00)Σ5.68]Σ28.18☐1.82﹜Σ30(Si70O175)[(OH)10.17F6.83]Σ17(H2O)17.75. Simplified and endmember formulae are as follows: (Cs,☐)6(☐,Cs)6(☐,K)6(REE,Ca,☐)30(Si70O175) (H2O,OH,F,☐)35 and Cs6(REE22Ca6)(Si70O175)(OH,F)14(H20)21. The crystal structure of mendeleevite-(Ce) is an intercalation of two independent Si—O radicals and an M framework of (REE,Ca) polyhedra. The Si—O radicals are an (Si140O260)104– framework and an (Si36O90)36– cluster which do not link directly. The M framework is located between the Si—O framework and the Si—O clusters. Interstitial cations occupy two types of cages and channels. Cages I and II are 78 and 22% occupied by Cs. Channels along [100↻] contain K atoms and H2O groups. Mendeleevite-(Ce) has no natural or synthetic structural analogues. Mendeleevite-(Ce) is a framework mineral with large cavities and it has the potential to be used as a model for the synthesis of microporous materials of industrial interest.

Ojuelaite was described from its occurrence at the Ojuela mine in Mapimi, Mexico by Cesbron et al. (1981). Those authors suggested that the phase was isostructural with whitmoreite (Moore et al., 1974), a phase of interest because of the unique arrangement of Fe octaheda in its octahedral sheet.

High-resolution X-ray emission spectra (XES) are presented for minerals with a variety of structures. The participation of the Si 3p orbitals in bonding is influenced by the local structure around the silicon atom. In orthosilicates the distortion of the SiO44--tetrahedron influences both peak-width and the intensity of the high-energy shoulder of the Si-Kβ spectrum. In minerals containing Si-O-Si bonds there is mixing of the Si 3s and 3p orbitals giving rise to a peak on the low-energy side of the main Si-Kβ peak. When combined with X-ray photoelectron spectra (XPS), a complete molecular orbital picture of bonding can be established.

Thebaite-(NH4), (NH4,K)3Al(C2O4)(PO3OH)2(H2O), is a new mineral species (IMA2020-072) from the Rowley mine, Maricopa County, Arizona, USA. It occurs in an unusual bat-guano-related, post-mining assemblage of phases that include a variety of vanadates, phosphates, oxalates and chlorides, some containing NH4+. Other secondary minerals found in association with thebaite-(NH4) are antipinite, vanadinite and at least one other new mineral. Crystals of thebaite-(NH4) are colourless blades up to ~0.1 mm in length. The streak is white, lustre is vitreous, Mohs hardness is 1½–2, tenacity is brittle and fracture is splintery. There are two good cleavages in the [010] zone, probably {100} and {10$\bar{2}$}. The calculated density is 2.093 g⋅cm–3. Thebaite-(NH4) is optically biaxial (–) with α = 1.490(2), β = 1.534(2), γ = 1.570(2) (white light); 2V = 82.7(5)°; slight r > v dispersion; and orientation X = b, Y ^ c = 13° in obtuse β. Electron microprobe analysis gave the empirical formula [(NH4)2.12K0.69Na0.20]Σ3.01(Al0.84Fe3+0.11V3+0.04)Σ0.99(C2O4)[(P0.98Si0.02)O3OH]2(H2O), with the C, N and H contents constrained by the crystal structure. Raman spectroscopy confirmed the presence of NH4 and C2O4. Thebaite-(NH4) is monoclinic, P21/c, with a = 11.156(9), b = 6.234(6), c = 18.651(16) Å, β = 102.928(15)°, V = 1264.2(19) Å3 and Z = 4. The structural unit in the crystal structure of thebaite-(NH4) (R1 = 0.0612 for 863 Io > 2σI reflections) is a double-strand chain of corner-sharing AlO6 octahedra and PO3OH tetrahedra decorated by additional PO3OH tetrahedra and C2O4 groups. The decorated chains connect to one another through bonds to NH4+ and K+ and through hydrogen bonds.

Magnesio-hornblende (IMA2017-059) has been characterized in a specimen collected in the sand dunes of Lüderitz, Karas Region, Namibia. The empirical formula derived from electron microprobe analysis and single-crystal structure refinement is A(□0.73Na0.22K0.05)Σ1.00B(Ca1.79Fe2+0.10Mg0.04Mn2+0.03Na0.04)Σ2.00C(Mg3.48Fe2+0.97Al0.28Fe3+0.23Cr3+0.01Ti0.03)Σ5.00T(Si7.18Al0.82)Σ8.00O22W[(OH)1.93F0.05Cl0.02]Σ2.00. Magnesio-hornblende is biaxial (–), with α = 1.640(2), β = 1.654(2), γ = 1.666(2) (measured with gel-filtered Na light, λ = 589.9 nm), 2V (meas.) = 82(1)° and 2V (calc.) = 84.9°. The unit-cell parameters are a = 9.8308(7), b = 18.0659(11), c = 5.2968(4) Å, β = 104.771(6)° and V = 909.64 (11) Å3 with Z = 2 and space group C2/m. The strongest eight reflections in the X-ray powder pattern [d values (in Å), I, (hkl)] are: 2.709, 100, (151); 8.412, 74, (110); 3.121, 73, (310); 2.541, 58, ($\bar{2}$02); 3.386, 49, (131); 2.596, 45, (061); 2.338, 41, ($\bar{3}$51); and 2.164, 39, (261).

The new mineral centennialite (IMA 2013-110), CaCu3(OH)6Cl2·nH2O, was identified from three cotype specimens originating from the Centennial Mine, Houghton County, Michigan, USA, where it occurs as a secondary product, after acid water action upon supergene Cu mineralization in association with, and essentially indivisible from, other copper-containing minerals such as calumetite and atacamite family minerals. It forms as pale to azure blue encrustations, often taking a botryoidal form. Centennialite is trigonal, , a = 6.6606(9) Å, c = 5.8004(8) Å, V= 222.85(6) Å3, Z= 1. The strongest powder X-ray diffraction lines are dobs/Å [I%] (hkl), 5.799 [100] (001), 2.583 [75] (201), 2.886 [51] (111), 1.665 [20] (220), 1.605 [17] (023), 1.600 [15] (221), 1.444 [11] (222). The X-ray refined structure forms a kagome net of planar coordinated CuO4 units with Jahn-Teller coordinated Cl apices to form octahedra that edge-share to in-plane adjacent and flattened CaO6 octahedra, which are centred about the lattice origin. All oxygen sites are protonated and shared between one Ca-octahedron and one CuO4 planar unit. Three protonated sites are linked, by hydrogen-bonding to Cl sites, which sit on the triad axis. Each lattice has one Cl above and one below the Ca-Cu polyhedral plane. Consequently, the layers are stacked, along ⟨001⟩, with two Cl sites between layers. In addition to this kapellasite-like topology, an extra c/2 site is identified as being variably water-hosting and extends the coordination of the Ca-site to 8-fold, akin to the body-diagonal Pb-Cu sheet in murdochite. Centennialite conforms to the description of the ‘Unidentified Cu-Ca-Cl Mineral’ noted in Heinrich's Mineralogy of Michigan and is almost certainly identical to the supposed hexagonal basic calcium-copper hydroxychloride monohydrate of Erdös et al. (1981). We comment upon relationships between calumetite and centennialite and propose a substructure model for a synthetic calumetite-like phase that is related directly to centennialite.

The degree of transport and retention of 14CH4 in soil is being investigated in a series of laboratory experiments in preparation for field scale trials at the University of Nottingham. The experimental programme focusses on the behaviour and fate of 14CH4 injected into subsoil and its subsequent incorporation into vegetation under field conditions. Due to restrictions on the use of radioactive tracers in the field, 13CH4 is being used as a surrogate gas which can be handled conveniently in the laboratory and field and which can be measured with high precision using gas chromatography with isotope ratio mass spectrometry. The laboratory data indicate significant differences between the diffusion and oxidation rates of 13CH4 in re-packed and undisturbed soil columns, with both rates appearing to be significantly lower in undisturbed soils. Data from both laboratory and field experiments will be used to inform the development of a model of 14CH4 migration and its fate in the biosphere above a geological disposal facility.

We have applied mechanical exfoliation for the preparation of ultra-thin samples of the phyllosilicate mineral biotite. We demonstrate that the 'scotch tape' approach, which was made famous as an early method for production of single-atom-thick graphene, can be used for production of sheet-silicate specimens that are sufficiently thin to allow high-resolution transmission electron microscope (HRTEM) imaging to be achieved successfully while also being free from the specimen preparation artefacts that are often caused by ion-beam milling techniques. Exfoliation of the biotite parallel to the (001) planes has produced layers as thin as two structural TOT units thick (∼2 nm). The minimal specimen thickness enabled not only HRTEM imaging but also the application of subsequent exit wavefunction restoration to reveal the pristine biotite lattice. Exit wavefunction restoration recovers the full complex electron wave from a focal series of HRTEM images, removing the effects of coherent lens aberrations. This combination of methods therefore produces images in which the observed features are readily interpreted to obtain atomic resolution structural information.

The characteristics of a phlogopite and its weathering product, vermiculite, have been studied by X-ray, infra-red, electron-microscope, and chemical methods. Inclusions within these minerals have been identified as thin films rich in iron oxide (which impart a schiller effect), spinel (which may exist in a preferred orientation), and serpentine. The orientation relationship between the fresh mica and its weathering product has been established by single-crystal methods. The mechanism of transformation from a 1-layer to a 2-layer polytype is discussed.