bluuebunny/crossref_metadata_2025_split huggingface dataset:
Crystal-liquid partition coefficients for pyroxene, spinels, and melilite, in slags
Authors: Wearing E. 
Published: December 2006

AbstractThe chemistry of spinels, plagioclase, and iron-rich, normally zoned pyroxene and melilite from some metallurgical slags has been investigated by electron microprobe analysis. Minor element partition coefficients, some of which are composition-dependent, have been calculated from the analytical data. The pyroxene/liquid partition coefficients range from 4.03 to 0.03 in the order Ti/Zr, Al, Mn, Zn, Ba, Sn, Na, reflecting increasing incompatibility. The spinel/liquid partition coefficients range from 40.89 to 0.02 but in the order Ti, Ni, Mg/Zn, Al, Mn, Cu, Sn, Zr. However, Sn becomes very compatible when the pyroxene and spinels crystallize in association with cassiterite. Melilite greatly discriminates against the incorporation of minor elements into its crystal structure. The crystallization of these phases produces residual liquids enriched in Na, Mn, Zn, Sn, Ba, W, and Pb.
Cr Mica from the Precambrian Erris Complex, NW Mayo, Ireland
Authors: Max Michael D. , Treloar P. J. , Winchester J. A. , Oppenheim M. J. 
Published: December 2006

AbstractCr micas identified as chrome phengites occur in association with other Cr-rich minerals in a peculiar schist which lies along a complex shear zone within the pre-Caledonian Erris Complex. The schist generally has a chaotic internal structure but locally there is a crude planar mineralogical zoning with a serpentinebearing zone structurally above a Cr mica zone. Chemical analyses indicate that the schist is a tectonic derivative of a mixture of rock with a pronounced metasomatic character.
Babingtonite, fluorapophyllite and sphene from Harcourt, Victoria, Australia
Authors: Birch W. D. 
Published: December 2006

AbstractSmall crystals of babingtonite and rare sphene occur in a coarse-grained aggregate of fluorapophyllite, stilbite, and calcite, infilling a late-stage cavity in granodiorite from Harcourt, Victoria. This is the first reported occurrence of babingtonite in Victoria. The assemblage crystallized from fluids in which Ca and F were significant and under P–T conditions of the order of 0.5 kbar, 100–150°C. Some of the fluorapophyllite has been altered to opaline silica suggesting that the residual solutions were acidic.
A ferric iron equivalent of hematolite from Sterling Hill, New Jersey and Långban, Sweden
Authors: Dunn Pete J. , Peacor Donald R. 
Published: December 2006

AbstractAn unnamed Fe3+analogue of hematolite is described from Sterling Hill, New Jersey and Långban, Sweden. Eight microprobe analyses are in good agreement with ratios derived from a prior analysis which yielded: Al2O30.24, Fe2O310.85, MgO 10.61, MnO 41.76, As2O36.65, As2O515.29, H2O 13.23 (rem. = 1.63), sum = 100.26 %. Single-crystal study indicated that this compound is hexagonal witha= 8.28 Å, but the value ofccould not be well-defined due to complex polytypism giving rise to diffuse and poorly resolved reflections alongc*. In one case, a value ofc= 72.69 Å was dominant. All values that could be determined were multiples of approximately 12 Å. The strongest lines in the X-ray powder diffraction pattern are: 2.400(100), 1.563(100), 6.09(80), 3.42(50), and 5.13(50). This compound is dark red and occurs as platy hexagonal crystals in clusters associated with a wide variety of species in varied assemblages. It remains unnamed because of the ambiguity arising from polytypism.
Munirite, naturally occurring sodium vanadium oxide hydrate, a new mineral
Authors: Butt K. A. , Mahmood K. 
Published: December 2006

AbstractMunirite was found in the sandstones of Siwaliks formation of mid-Miocene to Pleistocene age. It occurs as small globular clusters of acicular crystals (2 to 3 mm long). Analysis gave V2O5 67.46, N2O 22.91, and H2O 10.26%. The X-ray powder diffraction pattern shows remarkable similarity to a synthetic compound NaVO3 · 1.9H2O (Lukacs and Strausievici, 1962).
Zeophyllite from Monte Somma, Vesuvius, Italy
Authors: Passaglia Elio , Porcelli Cesare 
Published: December 2006

AbstractZeophyllite, a rare calcium silicate, occurs at Monte Somma, Italy, as milky-white, slightly fibrous spherules associated with apophyllite on the surface of pumice in a welded tuff dated 472 AD. The chemical analysis and the indexed powder pattern, along with the chemical formula and unit cell dimensions calculated from these data, are given. The deficiency of Ca and Si cations and the abundance of (OH) and F anions in the chemical formula calculated on the basis of 38 anions (O + F) is interpreted as due to the presence of (O4H4) substituting for (SiO4) tetrahedra and of fluorine instead of oxygen atoms in two anionic sites.
Thermodynamic mixing properties of pyrrhotine, Fe1_XS
Authors: Powell Roger 
Published: December 2006

AbstractPublished data from pyrrhotine-vapour equilibrium experiments are used to make inferences concerning the high-temperature thermodynamic mixing properties of pyrrhotine. Darken's quadratic formalism provides the justification for plotting activity of sulphur data against (1−X)2, where X is used in Fe1−XS to express the composition of non-stoichiometric pyrrhotine. Such plots show that the thermodynamic behaviour of pyrrhotine appears to be different on either side of X = 0.125, the Fe7S8 composition.
Silver substitution into synthetic zinc, cadmium, and iron tetrahedrites
Authors: Pattrick R. A. D. , Hall A. J. 
Published: December 2006

AbstractThe limits and effect on cell size of silver substitution into synthetic tetrahedrite, Cu10(Zn,Fe,Cd2) Sb4S13, are investigated for comparison with natural tetrahedrite. The limit of Ag substitution into natural zincian tetrahedrite is ∼ 4 atoms per half unit cell and into iron tetrahedrite ∼ 6.5 atoms (with rare exceptions). The cell size of natural tetrahedrite increases with increasing Ag content up to 4 atoms but decreases with further Ag substitution. The highest Ag substitution achieved in synthetic tetrahedrites was 4.7 atoms in Zn2-tetrahedrite, 7.02 atoms in Cd2-tetrahedrite and 6.80 atoms in Fe2-tetrahedrite. The cell size of synthetic tetrahedrites shows a continuous increase with increasing Ag content, the largest cell size ofa= 10.927 Å being in the Cd2-tetrahedrite with 7.02 atoms Ag. The iron content of tetrahedrite systematically increased from 1.1 to 2.0 atoms per half unit cell tetrahedrite with increase from 0 to ∼ 4 atoms Ag. The different limit of Ag substitution between Zn2and Cd2tetrahedrite can be explained by size constraints on the expanding structure. An explanation is given for a limit of 7 atoms Ag substitution in tetrahedrite using a combined electron band/molecular orbital approach.
Sulphur isotopes in metamorphosed Precambrian Fe-Pb-Zn-Cu sulphides and baryte at Aggeneys and Gamsberg, South Africa
Authors: von Gehlen K. , Nielsen H. , Chunnett I. , Rozendaal A. 
Published: December 2006

AbstractSulphur isotope ratios in sulphides and baryte from stratabound and stratiform orebodies in a metavolcanic-sedimentary sequence in Namaqualand were found, in part, to be extreme for Precambrian sulphur. Black Mountain, Aggeneys, in the west gave an average for the sulphides of δ34S = +8.9±3.7‰ (9 samples), an average for barytes of +20.6±4.3‰ (3 samples). Broken Hill, Aggeneys, in the centre gave an average for the sulphides of δ34S = +19.8±3.1‰ (19 samples). Gamsberg, in the east, gave an average for the sulphides of δ34S = +29.2±1.8‰ (24 samples), and an average for barytes of +35.4±0.2‰ (2 samples). The δ34S values increase eastward. Their range is strongly on the positive side and does not centre around zero. The Gamsberg barytes and most Gamsberg sulphides have more positive δ34S values than those reported for other Precambrian sulphides and sulphates. We interpret the above sulphur isotope range as being mainly due to the varying contributions of submarine-exhalative sulphide sulphur with δ34S close to zero and bacterially(?) reduced sulphate with strongly positive δ34S, apparently from evaporites in the east. Metamorphism of amphibolite facies grade has partly isotopically re-equilibrated the ore minerals, as indicated by galena-pyrrhotine and sulphide-baryte isotope temperatures from single specimens, but has not destroyed the primary sulphur isotope range indicating pre-existing sulphate concentrations.
Sphalerite composition in relation to deposition and metamorphism of the Foss stratiform Ba-Zn-Pb deposit, Aberfeldy, Scotland
Authors: Moles Norman R. 
Published: December 2006

AbstractSphalerite is a common constituent of the mineralized rocks and host metasediments of the Foss baryte-base metal deposit, located near Aberfeldy in the central Scottish Highlands. Microprobe analyses of sphalerite show a wide range in minor element content (0–17 mol. % FeS, 0–3 mol. % MnS), and sphalerites of contrasting composition are often found in the same rock. This suggests that equilibrium domains in some rocks were minute (< 1 mm), during regional metamorphism. Pressures derived from the selective application of the sphalerite geobarometer are consistent with other mineralogical evidence of peak metamorphic pressures in the range 7–10 kbar, at 540–580 °C. However, there is considerable evidence of partial retrograde re-equilibration of sphalerite, by continued buffering with pyrite+ pyrrhotine and by outward diffusion of iron. Marginal depletion of Fe and Mn in sphalerite within coarse carbonate rocks is attributed to partitioning reactions following recrystallization. Sphalerite which has retained its pre-metamorphic composition shows systematic variations in composition through profiles of mineralized beds, which may be related to depositional environments. Bimodal primary compositions can be explained by precipitation of zinc sulphides under the contrasting chemical environments of hydrothermal vents and cooler, exhaled brine layers on the sea floor.
The interpretation of pyrrhotine-pentlandite- tochilinite-magnetite-magnesite textures in serpentinites from Mount Keith, Western Australia
Authors: van de Vusse R. , Powell Roger 
Published: December 2006

AbstractThe ultramafic-hosted disseminated nickel sulphide deposit at Mount Keith, Western Australia, originally consisted of sulphide droplets and chrome spinels interstitial to olivine. During cooling, the sulphide droplets crystallized to pentlandite-pyrrhotine. Hydration and carbonation caused rimming and replacement of pentlandite-pyrrhotine by tochilinite, magnetite, and magnesite. These textures are interpreted in terms of diffusion between serpentinite matrix and the sulphide blebs.
Metamorphic features in Appalachian massive sulphides
Authors: Craig James R. 
Published: December 2006

AbstractMassive stratiform and stratabound sulphide bodies in the central Appalachians exhibit a wide variety of metamorphic features which are typical of similar deposits world-wide. The ores occur as lens- to plate-like bodies which are concordant with the enclosing meta-sediments and volcanics and are interpreted as products of Late Precambrian to Early Palaeozoic submarine volcanism. Sulphide mineralization ranges from pyritic to pyrrhotinic bodies with variable, but Zn- and Cu-dominant, base-metal contents. The deposits have been subjected to metamorphism ranging from greenschist to amphibolite grade. The metamorphism has been pervasive and has resulted in thorough recrystallization of most ores and intense deformation of pyrrhotinic ores, but does not appear to have significantly altered original sulphide assemblages. Recrystallization has homogenized most sulphide minerals including pyrite and sphalerite, so that any original compositional zoning is no longer seen. The presence of chalcopyrite has apparently promoted an increase in grain size and has facilitated post-metamorphic retrograde re-equilibration. Consequently, sphalerite geobarometry is not reliable in Cu-bearing assemblages. Pyrrhotines, mostly hexagonal, have re-equilibrated to low temperatures but commonly display pressure twins and kink-banding, apparently due to the late stages of deformation. Characteristic mineralogical changes in the host rocks include changes in the abundance of minerals, changes in the Fe: Mg ratios, and the presence of gahnite.
Rare earth element distribution in a metasomatic zoned ultramafic pod from Fiskenaesset, West Greenland
Authors: Fowler M. B. , Williams C. T. , Henderson P. 
Published: December 2006

AbstractThe distribution of REE in a zoned ultramafic pod formed by incomplete re-equilibration of ultrabasic and quartzofeldspathic reactant compositions has been studied. Transport of the heavy REE (HREE) as well as the light REE (LREE) over several metres has occurred during the diffusion-controlled metasomatism of the protolith mineral assemblages. The largest resultant concentration range (Eu) exceeds two orders of magnitude. In general, REE abundances increase towards the marginal zones, and differences between the behaviour of LREE, middle REE (MREE) and HREE subgroups are observed. LREE are least mobile in the aqueous transporting medium. Complexing by carbonate ligands is probably not an important factor in this system, and the final REE distribution is thought to be governed largely by the crystal structure of the major zonal minerals.
Magnesian högbomite in a sapphirine-bearing rock from the Fiskenaesset region, W. Greenland
Authors: Ackermand D. , Windley B. F. , Herd R. K. 
Published: December 2006

AbstractHögbomite occurs in a 20 × 80 cm gedrite-rich lens between meta-volcanic amphibolite and anorthosite at the top of the Fiskenaesset Complex in the Angnertussoq area 13 km SE of Fiskenaesset. Between coarse prismatic gedrites there are dusters with chlorite, spinel, sapphirine, rutile, högbomite and corundum. Högbomite forms 200 µm grains often associated with rutile, surrounded by spinel and sapphirine but never in contact with gedrite. Usually sapphirine forms rims on spinel and contains relict gedrite. Corundum is intergrown with spinel and sapphirine. Reactions suggested by the textures are: 1. Gedrite + spinel + rutile → sapphirine + högbomite + chlorite. 2. Sapphirine → chlorite + corundum + spinel. 3. Högbomite → rutile + corundum + spinel. In some areas without rutile or högbomite the reaction gedrite + spinel + ? → sapphirine + chlorite took place.Mg/(Mg + Fe + Mn) ratios are in the following order: sapphirine (0.95–0.92) > chlorite (0.94) > hornblende (∼ 0.91) > anthophyllite (∼ 0.86) > gedrite (∼ 0.86) > spinel (0.77–0.74) > högbomite (0.75–0.71). Högbomite usually has an anhydrous total of c. 98 %; on the basis of 31 oxygens and with total Fe as FeO one representative analysis has Mg 4.59, Fe 1.73, Zn 0.02, Ni 0.05, Al 14.78, Cr 0.02, Ti 1.2 atoms per formula unit.
Mineralogical and petrological studies of Jurassic and Cretaceous sediments from southern England and their relevance to radioactive waste disposal
Authors: Milodowski A. E. , Wilmot R. D. 
Published: December 2006

AbstractA sequence of sedimentary rocks from the Lower Chalk to the Oxford Clay has been studied as part of a reasearch programme into the feasibility of the disposal of low- and intermediate-level radioactive wastes in argillaceous strata. The preservation of aragonite in such rocks suggests that little groundwater movement has occurred through the bulk of these clays and this would imply that most groundwater movement is likely to occur along any fractures that may be present. Such fractures may interconnect with adjacent aquifer units along which most transport of radionuclides would occur. In these sediments the presence of smectitic clay minerals would strongly influence their retention of radionuclides by sorption and ion-exchange reactions. Compaction, calcite cementation, calcite dissolution and the diagenesis of biogenic silica have influenced the porosity and permeability of the rocks. These processes have also controlled the chemistry of many pore surfaces in contact with groundwater and these in turn will affect groundwater chemistry, and the nature of interactions with transported radionuclides.
An investigation of olivine crystal growth in a picrite dyke, using the fission track method
Authors: Henderson Paul , Sélo Madeleine , Storzer Dieter 
Published: December 2006

AbstractA picrite dyke with an olivine-bearing chilled margin and an olivine-rich centre has been used to test for the presence of a boundary layer around rapidly grown olivine crystals and for any variations in the olivine/melt partition coefficient for uranium as a result of probably different crystal growth rates. The technique of fission-track mapping is shown to be suitable for this kind of study despite the very low uranium concentrations in the olivines. A boundary layer appears to be present around some olivine crystals but it is not a consistent feature. Uranium partition between olivine and melt was not affected by different crystal growth rates, as revealed by different crystal morphologies.
Baghdadite, a new calcium zirconium silicate mineral from Iraq
Authors: Al-Hermezi H. M. , McKie D. , Hall A. J. 
Published: December 2006

AbstractBaghdadite, a new calcium zirconium silicate mineral has been found in melilite skarn in contact with banded diorite, from the Qala-Dizeh region, NE Iraq. Electron microprobe analysis yielded: SiO2 = 29.26, ZrO2 = 27.00, TiO2 = 2.11, Fe2O3 = 0.11, Al2O3 = 0.03, MgO = 0.05, CaO = 41.44, Na2O = 0.02, sum = 100.02 wt. %. The mineral contains about 0.16% HfO2. This analysis calculates to Ca3.00(Zr0.89Ti0.11)(Si1.98Fe0.01)O9 which leads to the ideal formula Ca3Zr[O2|Si2O7]. X-ray single crystal study showed it to be monoclinic with space group P21/a. The unit cell dimensions are: a = 10.42(2), b = 10.16(2), c = 7.36(1) Å, β = 91.1°, Z = 4 and cell volume = 779.04 Å3. The seven strongest lines in the powder diffraction pattern are (d,I,hkl): 7.30 (45)(110), 3.23 (80)(130), 3.04 (75)(2̄02), 2.98 (85)(202), 2.88 (70)(320,212), 2.84 (100)(230), 1.702 (40)(522). It is colourless, lustre vitreous, no cleavage and VHN50 = 725–783 kg mm−2 with H ∼ 6. Calculated density = 3.48 g cm−3 which is very close to 3.46 measured density of a synthetic Ca3ZrSi2O9. It is optically biaxial, positive, 2 V ∼ 72°, dispersion indiscernible. The cathodoluminescence colour is dull grey with a greenish tint. Refractive indices: α= 1.652, β = 1.658, γ = 1.670. The crystal habit is stumpy prismatic and a contact twin with b as twinning axis is observed. Optic orientation: α = c, β//b, γ = a.
Mantle-derived sapphirine
Authors: Griffin W. L. , O'Reilly S. Y. 
Published: December 2006

AbstractA xenolith from the Delegate breccia pipe (New South Wales, Australia) contains sapphirine in equilibrium with aluminous clinopyroxene, garnet, and plagioclase (An48). This unusual assemblage probably developed from a clinopyroxene (±spinel ± plagioclase) cumulate during cooling from > 1400°C to c. 1000°C at pressures near 15 kbar. The sapphirine is close to the 7:9:3 composition, suggesting that bulk composition is more important than P-T conditions in determining the stoichiometry of natural sapphirines. A similar occurrence of sapphirine has also been recorded in mantlederived xenoliths from the Stockdale kimberlite in Kansas. Re-examination of sapphirine granulites from Finero suggests that their primary assemblages and origin may have been similar to those of the Delegate xenolith. Sapphirine is clearly stable under upper-mantle conditions in Ca-Al-Mg-rich bulk compositions.
Silver mineralization at the Vale das Gatas tungsten mine, Portugal
Authors: Gaspar O. , Bowles J. F. W. , Shepherd T. J. 
Published: December 2006

AbstractThe Vale das Gatas tungsten mine is situated at the contact between Hercynian granite and Cambrian-Precambrian crystalline schists a few kilometers north of the village of Sabrosa, near Vila Real, in northern Portugal. Wolframite has been the principal product of the mine although several other metals of economic interest are known to occur there. The silver content of the ores was attributed by earlier workers to the presence of tetrahedrite and schapbachite, whilst this work shows matildite, pavonite, acanthite, and argyrodite to be present, together with Ag-bearing galena. The textures and compositions of these phases are described with preliminary results of fluid inclusion studies.
Growth twinning in phacolite
Authors: Akizuki Mizuhiko , Konno Hiroshi 
Published: December 2006

AbstractPhacolite from Mitaki, Sendai City, Japan, has a core of penetration-twinned chabazite. The crystal has a convex (0001) face on which many twin individuals are produced by a two-dimensional nucleation mechanism, resulting in complicated twinning during growth. Both the r and the faces repeat finely during growth because of twinning, resulting in {112̄3} sectors with polysynthetic twinning. Finally, single structures nucleate on the crystal edges [211̄] and develop along the (112̄3) face, penetrating each other near the centre of the face.
An explanation of optical variation in yugawaralite
Authors: Akizuki Mizuhiko 
Published: December 2006

AbstractYugawaralites from two localities in Japan consist of growth sectors with variable 2V values and extinction angles. The optical variations cannot be explained on chemical grounds because the mineral shows very little chemical variation but they can be explained on the basis of Al/Si ordering. The v{021} sectors (Pa setting) are composed of optically triclinic bands, and the k{110} sector consists of both triclinic bands and monoclinic homogeneous domains. An electrostatic charge of the Al/Si ordered structure is balanced along a two-dimensional atomic arrangement exposed on the side face of a growth step. If the Si tetrahedron is produced after the calcium ion, the Si ion will be replaced during growth by an Al ion due to the local effect of the calcium ions. When a side plane of growth steps of yugawaralite is not normal to the (010) glide plane, a symmetrical equivalence of two Si sites with respect to the Ca ion will be lost at the surface, and as a consequence ordering will occur and the symmetry of crystal will be reduced. The monoclinic, homogeneous sector might be produced on the very finely kinked surface. The space group of the triclinic sector will be P1, while that of the monoclinic sector will be Pc.
Deerite from Papua New Guinea
Authors: Worthing M. A. 
Published: December 2006

AbstractDeerite in two meta-ironstones from Papua New Guinea coexists with quartz-albite-riebeckite-dannemorite-magnetite-spessartine-stilpnomelane-apatite-Ca/Mn carbonates and quartz-albite-crossite-ilmenite-spessartine-stilpnomelane-apatite respectively. Geochemical comparisons in the system FeO-MnO-MgO suggest that the P.N.G. deerites most closely resemble Franciscan types. However, the metamorphic assemblages more closely resemble Alpine types indicating metamorphism close to the lower P-T limit of deerite stability. Consistent differences in whole-rock and internal oxidation ratios between the two specimens suggest that fo2 may be important in determining deerite chemistry. A redox equation is suggested linking changes in deerite internal oxidation ratio with variable OH content.
A miniclave for experiments up to 4 kbar and 1200 °C used to study REE-carbonate glasses
Authors: Jones A. P. , Maaloe S. 
Published: December 2006

AbstractGlasses quenched from synthetic REE-carbonatite liquids in recent Tuttle bomb experiments require fast cooling rates. To study these glasses further, an internally-heated miniclave has been developed to increase quench rates and extend the operating P-T range of standard Tuttle bombs. The Haskel miniclave can achieve simultaneous P and T of up to 1200°C at 4 kbar for small diameter (1–2 mm) samples. Gas (Argon) pressure is supplied by a small intensifier unit and heating by an internal platinum-wound furnace. Because of the relatively small thermal mass, run temperatures can be reached within a few minutes and quench rates approach those of solid media apparatus.