The evolution with pressure of the CH4 vibrational modes related to C–H stretching has been followed by in situ Raman spectroscopy on a single crystal of cubic melanophlogite from Varano Marchesi (Parma, Italy) containing only CH4 in the cages. The sample was compressed hydrostatically in a diamond anvil cell up to 6.5 GPa, using a non-penetrating P-transmitting medium. Two modes at 2900 and 2910 cm–1 (ν1 and ν2) were followed in response to the applied pressure, corresponding to C–H stretching of CH4 enclathrated in the 51262 and 512 cages, respectively. A change in slope of the frequency vs. P linear trend of the sharper peak at 2900 cm–1, observed between 1 and 1.5 GPa, is interpreted as evidence of the P-induced cubic to tetragonal transition, previously observed by X-ray diffraction at P ≥ 1.2 GPa. At pressures below the transition, the shift with P of the CH4 modes is comparable to that observed in methane ice hydrate, which becomes hexagonal at P ≥ 0.9 GPa however. The ratio of the integrated areas of the two C–H stretching Raman peaks does not change significantly with pressure across the transition. At P ≥ 5.1 GPa, a shoulder appears, close to the n1 peak, along with a slight change in slope of peak shift and peak broadening. The shoulder is maintained in decompression down to P = 4.4 GPa, showing slight hysteresis. At the same pressures however, X-ray diffraction shows no evidence of a phase transition, suggesting that a rearrangement of CH4 configuration occurs, without any effect on the tetrahedral framework.

The name hauchecornite has been applied in the literature to a group of minerals with similar crystal structures and the general formula (Ni,Co,Fe)9ABS8, where A and B are As, Sb, Bi, and Te in two nonequivalent structural sites. A classification of the group is proposed based on the relative abundance of the elements As, Sb, Bi, and Te in the two sites. Hauchecornite is redefined as Ni9BiSbS8, the end-member being closely approximated by the composition of the material from the type locality, and a new name, bismutohauchecornite, is proposed for the Ni9Bi2S8 end-member. The classification, redefinition, and the new name have been approved by the Commission on New Minerals and Mineral Names, IMA.

Holmquistite idioblasts occur in a hornblende-titanite-quartz-plagioclase amphibolite, in contact with a lithium (spodumene) pegmatite at Greenbushes, Western Australia. Unit cell parameters, chemical data and the results of a mineralogical investigation of holmquistite and associated minerals in the amphibolite are given.

The morphologies of hydrothermally grown reedmergnerite crystals change systematically with time and rate of change of B, Si order. Three stages in this process are recognized: (1) Growth of well-faceted crystals. (2) Development of etching leading to the formation of irregular grains. (3) Modification of irregular grains to form rounded or ellipsoidal crystals. A solutionreprecipitation process is responsible for the morphological changes and the increase in degree of order of B and Si with time at constant temperature and pressure.

The position of the rhombic section of plagioclase felspars, as calculated from the measured cell dimensions, has been shown to vary with the structural state, the variation from high- to low-temperature forms being most pronounced for albite. The theoretical composition plane of pericline twins is the rhombic section. If the structural state or the composition of the felspar changes after twinning has occurred, the cell dimensions and hence the rhombic section will change; however, the composition plane of the pericline twin will probably remain unchanged unless recrystallization occurs, or perhaps if the felspar is subjected to strong stress. Thus the observed pericline composition plane need not coincide with the rhombic section. Comparison of observed composition planes with the corresponding calculated rhombie sections shows that some of them do indeed differ and the differences have been used to provide information on the changes occurring subsequent to the establishment of the pericline twins. The interpretation is complicated by the occurrence of the acline-A twin, whose composition plane is {001}, for the rhombie section of plagioclase felspars from An0 to An60 may coincide with {001} if the structural state of inversion has a particular value. When the observed composition would agree with both pericline and acline-A twinning, the new term b-axis twin has been used.

The 100 Ma complex LCT-type composite pegmatite- aplite dykes, intruded into various units of the Southern California Batholith, are known to contain bismuth minerals. Jahns and Wright (1951) reported the following primary and secondary bismuth minerals from the quartz-rich cores of a number of dykes in the Pala district, San Diego Co., California: native bismuth, bismuthinite, bismite, bismutite, and beyerite.

Natrotitanite, ideally (Na0.5Y0.5)Ti(SiO4)O, is a new mineral from the Verkhnee Espe rare-element deposit at the northern exo-contact of the Akjailyautas granite massif in the northern part of the Tarbagatai mountain range, Eastern Kazakhstan. Both the mineral and the name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA 2010-033). Star-shaped aggregates of small short prisms of yellow or yellowish white (Na,Y,REE)-bearing titanite rimmed by thin (∼2 μm) rims of natrotitanite are embedded in yttrium-bearing fluorite and replace narsarsukite. Associated minerals are microcline, albite, quartz, riebeckite, aegirine, biotite, astrophyllite, rutile, zircon and elpidite. Natrotitanite is milky white to yellowish grey, transparent to translucent, and has a white streak and a vitreous lustre. It shows pale orange cathodoluminescence but does not fluoresce under ultraviolet light. It shows no cleavage or parting, and is brittle; the calculated density is 3.833 g cm–3. The indices of refraction, measured with the Bloss spindle stage for the wavelength 590 nm using a gel filter, are α = 1.904, γ = 2.030, and these values are in accord with the mean refractive index, 1.988, calculated from the Gladstone-Dale relation. Natrotitanite is monoclinic, C2/c, a = 6.5691(2), b = 8.6869(3), c = 7.0924(2) Å, β = 114.1269(4)°, V = 369.4(2) Å3, Z = 4, a:b:c = 0.7562:1: 0.8164. The seven strongest lines in the X-ray powder diffraction pattern [in the order d (Å), I, (hkl)] are as follows: 2.597, 10, (130); 3.248, 8, (11); 2.994, 6, (200); 1.641, 4, (330); 4.941, 3, (110); 1.498, 3, (400); 2.273, 3, (11). Chemical analysis by electron microprobe gave Nb2O5 1.28, SiO2 27.83, TiO2 35.00, SnO2 0.57, V2O3 0.36, Fe2O3 0.23, Y2O3 7.87, Ce2O3 0.83, Sm2O3 0.26, Gd2O3 0.46, Tb2O3 0.17, Dy2O3 2.45, Ho2O3 0.16, Er2O3 2.24, Tm2O3 0.50, Yb2O3 2.53, Nd2O3 0.35, Lu2O3 0.28, MnO 0.33, CaO 8.16, Na2O 5.55, F 1.52 O ≡ F –0.64, sum 98.71 wt.%. The resulting empirical formula is (Na0.39Ca0.32Y0.15Dy0.03Yb0.03Er0.03Ce0.01Ho0.01Tm0.01Gd0.01Nd0.01)Σ1.00(Ti0.95Nb0.02Sn0.01Fe3+0.01Mn0.01V0.01)Σ1.01Si1.01O4.00(O0.83F0.17), calculated on the basis of 3 cations per formula unit. The general formula is written as (Na,Ca,Y,REE)TiSiO4(O,F), and the endmember formula is (Na0.5Y0.5)Ti(SiO4)O.

The crystal structure of a composite optically continuous crystal of natrotitanite and (Na, Y)-bearing titanite was mounted on a Bruker D8 three-circle diffractometer equipped with a rotating anode generator (MoKα radiation), a multi-layer optics incident-beam path and an APEX-II CCD detector. The crystal structure was refined in space group C2/c to a final R1 index of 1.8%. Natrotitanite is isostructural with titanite, (Na + Y + REE) replacing Ca at the Ca site in the titanite structure.

Russellite Bi2O3. WO3 occurs in a small pegmatite near Poona, Western Australia. The fine-grained yellow to pale green material is an inseparable mixture of russellite, bismite, koechlinite, and bismutite. X-ray powder diffraction, physical, and chemical data agree in general with the original description of the mineral from Cornwall, England. The original analyses made on micro quantities are now supplemented by analyses on macro quantities.

The granites of Sardinia have been analysed for copper, lead, and zinc, and each element has been found to show a regional variation. There is a close relationship between the copper and lead contents of the granites and the distribution of copper and lead mineralization in the island, but very little relation between the zinc contents of the granites and the distribution of zinc mineralization. This is attributed to a greater degree of lithophile character of zinc in the magmatic source region.

Sulphide minerals and their analogues yield gases as a result of oxidation reactions. Even where sulphide minerals are in contact with mildly reducing groundwaters, S2- ions pass into solution and their dispersion patterns can be detected in soil as acid-released H2S. In more oxidising conditions, the metastable gases COS and CS2 are generated. Anomalous dispersion patterns of COS have been reported in soils above more than ten sulphide ore deposits, many of them concealed beneath transported exotic overburden. High concentrations of CS2 occur in the soils over several of the same deposits and uniquely reflect others. Anomalies of SO2 over sulphide deposits are confined to arid terrains. Certain anomalous dispersion patterns of arsenic and tellurium in soils are attributed to the generation and migration of unspecified gases from the oxidation of arsenide and telluride minerals.

The crystal structures of nine, and the chemical compositions of ten, natural samples of leucophanite, ideally NaCaBeSi2O6F, were investigated. The analysed samples display a large compositional variation with trace-element abundances >50,000 ppm, primarily due to rare earth elements (REE). Fromthese data, we propose a substitution scheme for the incorporation of REE for Ca, with additional Na substituting for Ca and the generation of vacancies to ensure charge balance. Compositional zonation was observed in some samples; this zonation correlates with variations in cathodoluminescence. The crystal structure of the nine analysed samples could all be refined in space group P212121. We found no evidence for a reduction of symmetry with increased trace-element concentration. Various twin combinations were observed and these seem related to crystallization conditions rather than structural or chemical factors.

Spherulitic and felted green to brown minerals are described from various volcanic rocks of the Western Ochils, Stirlingshire. They fill amygdales and replace pyroxenes and appear to be an interlayered series of sheet silicates from celadonite to vermiculite. The minerals are hydrothermal in origin and suggest the presence of a potassium-rich hydrous fluid at a late stage in the volcanic history.

Rappoldite, the Co-analogue of helmutwinklerite, and zincgartrellite, the Zn-dominant analogue of gartrellite, are two new members of the tsumcorite group. Both minerals are triclinic, their structures are closely related to the parent structure, i.e. the ‘tsumcorite type’ (C2/m, Z = 2). The lower symmetry is caused by two different crystal-chemical requirements. Order phenomena of the hydrogen bonds cause the ‘helmutwinklerite type’ (P1̄, Z= 4), ordering of Cu2+and Fe3+ is responsible for the ‘gartrellite type’ (P1̄, Z = 1).

Rappoldite was found on samples from the Rappold mine near Schneeberg, Saxony, Germany. The new species forms red to red-brown prismatic and tabular crystals up to 1 mm long. Dcalc. = 5.28 g/cm3. 2Vz = 85(5)°, nx = 1.85 (calc.), ny = 1.87(2) and nz = 1.90(2); dispersion is distinct with r > v; orientation is Y ∼∥ [1̄ 20] and X ∼ ∥ c. The empirical formula derived from electron microprobe analyses is (Pb1.01Ca0.01)Σ1.02(Co0.99Ni0.62Zn0.35Fe0.02)Σ1.98[(AsO4)1.99(SO4)0.01]Σ2.00[(OH)0.02(H2O)1.98]Σ2.00 or Pb(Co,Ni)2(AsO4)2·2H2O. Single-crystal X-ray studies showed average C2/m symmetry. Weak superstructure reflections are responsible for triclinic symmetry and enlarged cell metrics (refined from powder data): a= 11.190(2)Å, b= 10.548(2)Å, c= 7.593(1)Å, α = 100.38(1)8, β = 109.59(2)8, γ = 98.96(1)8, V= 807.6 Å3, Z= 4. The superstructure results from the hydrogen-bond scheme, but faint streaks indicate some disorder. All investigated rappoldite crystals are twinned by reflection on (23̄0) which corresponds to the mirror plane of the average C2/m cell. Helmutwinklerite is isotypic with rappoldite and probably also with pure thometzekite; sulphatian thometzekite is monoclinic.

Zincgartrellite forms green-yellow rosette-like aggregates on samples from the Tsumeb mine, Namibia. The Dcalc. = 5.30 g/cm3. 2Vx = 87(5)°, nx = 1.91(2), ny = 1.94 (calc.) and nz = 1.97(2). Electron-microprobe analyses and Mössbauer data yielded the empirical formula (Pb0.97Ca0.04)Σ1.01(Zn0.91Cu0.51Fe0.59Al0.03)Σ2.04[(AsO4)1.96(SO4)0.01]Σ1.97[(OH)0.81(H2O)1.31]Σ2.12 or Pb(Zn,Fe,Cu)2(AsO4)2(H2O,OH)2. The structural formula is Pb(ZnxFe1–x)(ZnxCu1–x)(AsO4)2(OH)1–x(H2O)1+xwith 0.4 < x < 0.8. Gartrellite is defined by x < 0.4. Helmutwinklerite has x near to 1 and is defined by a cell with fourfold volume. Single-crystal X-ray studies of zincgartrellite proved space group P1̄ caused by ordering of Fe3+ and Cu at one atomic site. Cell parameters (refined from powder data): a= 5.550(1)Å, b= 5.620(1)Å, c= 7.621(1)Å, α = 68.59(1), β = 69.17(1), γ = 69.51(1)°, V= 200.1 Å3, Z= 1.

Gortdrumite superficially resembles chalcocite but is more distinctly anisotropic, and is present in a vein containing ferroan dolomite and baryte which cuts dolomitized limestones from the Gortdrum Orebody of County Tipperary, Ireland. It has an empirical formula of approximately (Cu,Fe)6Hg2S5. A distinctive powder diffraction X-ray pattern has been obtained which indicates a probable orthorhombic crystal lattice with a 14.96, b 7.90, and c 24.1 Å. The reflectivity at 589 nm is 25.1 to 27.9% and the VHN10 hardness range 186 to 230.

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.

Phases present in slags from Araxá (Brazil), Oka (Quebec) and Fen (Norway) resulting from the production of ferroniobium by the aluminothermic reduction of pyrochlore-group minerals are a function of composition of the pyrochlore feed and the diverse fluxes (CaO, CaF2) added to the alumina and iron oxide used in the reduction process. Absent from all slags investigated are Fe-bearing compounds. All of the slags are modally-dominated by prismatic crystals of β-alumina or hibonite, with a wide variety of Th-Ba-Ti-Nb-Al-oxide compounds and silico-aluminate glasses occurring in the interstices between these crystals. Slag from Fen consists of a framework of β-alumina (Ba and/or CaTi varieties) with a barian titanian niobate, considered to be an highly reduced Nb3+- and Ti3+-bearing anion deficient perovskite, as the first oxide phase to crystallize. This was followed by a Zr-Ti-Th-niobate (21.7–24.1 wt.% ThO2), a Nb-rich, Thbearing zirconolite-like phase (17.7–21.2 wt.%; Nb2O5; 6.8–9.5 wt.% ThO2) and diverse Th-Nb-rich, Alpoor (< 1 wt.% Al2O3) perovskites (29.4–40.5 wt.% Nb2O5; 3.3–11.4 wt.% ThO2). The latter represents a NaNbO3–CaTiO3–Na2/3Th1/3TiO3–ThTi2O6 solid solution. Late Na-rich silicate glass contains celsian. Slag from Araxá also consists of a framework of β-alumina (Ti-poor). Interstitial compounds differ from Fen in being predominantly rare-earth element (REE)-Nb-Al-Th-perovskites belonging to a REEAlO3–Ca2AlNbO6–CaTiO3–ThTi2O6 solid solution with minor NaNbO3 and CaZrO3, and compositionally diverse barium calcium aluminates [(Ba, Ca)Al2O4] set in a F-bearing (6–7 wt.%) Na-Ba-Si-aluminate glass with minor Ba4Nb2O9, CaF2, BaF2 and NaF. Slag from Oka consists of a framework of hibonite [(Ca, REE) (Al, Ti, Mg)12O19] zoned with respect to the REE content. Interstitial compounds are CaZr4O9, Nb-Th-poor perovskites belonging to the REEAlO3–CaTiO3 series with minor CaZrO3 set in a F-bearing (5–6 wt.%) calcium aluminate glass. These data demonstrate that during ferroniobium production REE, Zr, Th, U and significant amounts of Nb are sequestered in the oxide phases in accord with their lithophile geochemical character. None of these elements are present as compounds in the siderophillic ferroniobium alloys. These data demonstrate that the aluminothermic reduction process results in the loss of significant amounts of Nb to the slag. Perovskite-group compounds are present in all of the slags but differ widely in their composition as a result of compositional differences in the feed pyrochlores and fluxes added to the smelting process. Slags originating from ferroniobium production are enriched in Th and U and could be considered as an environmental hazard if these elements are mobilized during chemical weathering of slag.

The crystal structure of Ni-rich gordaite–thérèsemagnanite has been determined from a sample collected at pillar 80 in the North mine, Cap Garonne, Var, France. The structure was refined to R1 = 0.0693 for 935 reflections with I > 2σ(I). The mineral is isostructural with gordaite, forming a layered structure with an extensive hydrogen-bonding network. The possible polytypic relationship between gordaite, thérèsemagnanite and guarinoite is also discussed. The guarinoite formula (Zn,Co,Ni)6(SO4)(OH,Cl)10·5H2O is also likely to be incorrect and is more likely to be Na(Zn,Co)4(SO4)(OH)6Cl·5–6H2O, meaning that guarinoite is equivalent to Co-rich gordaite-2H and would not be a distinct mineral species.

The evolution of Fe-containing phases of carbonaceous chondrites heated under various oxidation-reduction conditions was investigated by means of Mössbauer spectroscopy. Heating of the lower petrological types of chondrites (CM2) released gases which initially produced oxidizing conditions (∼450°C) and then reducing conditions (> 700°C Phase transformation occurred rapidly (during 1–5 minutes) at all temperatures. During heating the Fe-bearing phyllosilicate phases in CM2-chondrite converted to Fe-bearing olivine, metallic iron and troilite (pentlandite). These phases resemble those of CO3, CV3 and EH-chondrites. Iron distribution resembling that of ordinary chondrites (some additional Fe2+ in pyroxene) was obtained only by heating a mixture of oxidized matter (CM2) with reduced matter (EH).

A phase transition discovered at 1050°C is probably the temperature boundary between conditions of formation of the two main components of ordinary chondrites: matrix and chondrules. Chondrules of ordinary chondrites may be formed at temperatures > 1050°C while the matrix forms at temperatures < 1050°C For the carbonaceous chondrite Kainzas (CO3) these temperatures are approximately 1000°C and < 900°C The experimental conditions determined for the evolution of chondrites do not contradict the theoretical two-component model of Wood-Anders-Ringwood and may further its development.