bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Rewari meteorite
Authors: Das Gupta S. P. , Sen Gupta P. R. , Sen Gupta N. R. , Das Gupta D. R. , Dube A. 
Published: December 2006

SummaryThe meteorite was an oriented polyhedron, which broke up into at least two parts after entry into the Earth's atmosphere. It has undergone some degree of terrestrial weathering. A cut surface of the meteorite shows light-grey interior with sporadic rusty-brown patches and a distinct brown alteration zone close to the fusion crust. Weathering has resulted in preferential replacement of NiFe by limonite, and veining of minerals by goethite.Rewari is an equilibrated chondrite with rare ghosts of chondrules and at least one lithic fragment. Composition of olivine, as indicated by microprobe analysis is Fa23, which agrees well with bulk wet chemical analysis; that indicated by d130 is Fa18–20. From the outer surface inwards, four petrographic zones can be distinguished in the meteorite: a skin, about 0.01 mm thick, a troilite-poor zone slightly thicker than the skin, a troilite-rich ‘soaking zone’, about 0.5–0.6 mm thick, and a relatively coarse-grained interior. These are described in detail.The interior of the meteorite is composed of relatively coarse-grained crystalline silicates with disseminated metallic minerals including plessitic and zoned inter-growths of kamacite and taenite. The matrix shows a high degree of integration with the chondrules. The coarse texture and zonation of taenite may be the result of protracted heat treatment responsible for recrystallization. The constituent grains show considerable shock effects such as fracturing, comminution, veins of shock-melted pseudotachylite, pressure twinning, and undulose extinction. Chemical composition (mean of two wet chemical analysis) of the meteorite is: metallic Fe 7.475, Ni 0.975, Co 0.045; as sulphide Fe 3.200, Ni 0.090, Co < 0.01; SiO2 38.060, TiO2 0.10, Al2O3 2.34, Fe2O3 0.175, Cr2O3 0.485, FeO 13.950, MnO 0.210, NiO trace, CaO 1.875, MgO 26.265, Na2O 0.89, K2O 0.115, P2O5 0.285, H2O− 0.295, H2O+ 0.81, CO2 trace, S (total) 1.890, C (total) 0.19 per cent. The chemistry, mineralogy, and texture show that the Rewari meteorite is an L6 chondrite. Compared to average L-group chondrite it has a higher content of MgO and lower of SiO2, a little lower oxidation state, and tends to be enriched in siderophilic elements.
The thermal expansion of aluminate- and aluminogermanate-sodalites
Authors: Henderson C. M. B. , Taylor D. 
Published: December 2006

SynopsisDiscontinuities occurring in the expansion behaviour of aluminosilicate-sodalites with large cavity anions such as I− and are thought to occur when the coordinate of the cavity cation becomes 0.25 (Henderson and Taylor, 1978). We also suggested that further thermal expansion work could explore how the disposition of sodalites in a diagram such as fig. 4 of Henderson and Taylor relates to the presence or absence of discontinuities.We have now studied the expansion of three more sodalites which were expected to show discontinuities, namely one aluminogermanate-sodalite (Na8(Al6Ge6O24)I2) and two aluminate-sodalites (Sr8(Al12O24)(CrO4)2 and Sr2Ba6(Al12 O24)(SO4)2). Sr8(Al12O24)(CrO4)2 was thought to have an ∼ 9 Å cubic cell at room temperature but the occurrence of broadened and split reflections in our sample suggests that this is not the case. Stepwise heating experiments on our sample showed the presence of a reversible, presumably displacive, transformation at 40±2 °C above which the X-ray reflections were sharp.All three sodalites showed significantly smaller expansion rates than for aluminosilicate-sodalites having similar degrees of structural collapse. The lower mean expansion coefficient (0–500 °C) for Na8(Al6Ge6O24)I2 of 12.5 × 10−6C−1 compared with that for Na8(Al6Si6O24)I2 of 15.1 × 10−6C−1 is particularly significant as the only chemical difference between these two phases is substitution of Ge for Si. In addition none of the three sodalites showed the discontinuities expected and this suggests that the low expansion rates do not allow the cavity cation to reach a coordinate of 0.25 over the temperature range investigated.Our earlier concept of the mechanism of expansion of the sodalite structure assumed that the expansion of the cavity cation-cavity anion bond forced the cavity cations against and between the framework oxygens so untwisting the partially collapsed structure (Henderson and Taylor, 1978). It now appears that this concept was over-simplified and that the expansion characteristics of sodalites depend on the nature of the tetrahedrally coordinated framework cations present as well as on the cavity cations and anions.
Margarite from the Olary Province of South Australia
Authors: Teale Graham S. 
Published: December 2006

SynopsisIn Lower Proterozoic rocks of the Olary Province of South Australia margarite occurs in conjunction with sodic muscovite, pseudomorphing chiastolitic andalusite in graphite-rich schist, and as a pseudomorphic phase in rocks consisting of coarse muscovite together with lesser amounts of chloritoid, sillimanite, staurolite, and corundum. In the latter occurrence the assemblage (muscovite-sillimanite - chloritoid ± staurolite ± corundum) replaces massive andalusite. The margarite and sodic muscovite within the pseudomorphs lack a preferred orientation which suggests that their development was associated with the waning stages of the Palaeozoic Delamerian Orogeny (cf. Glen et al., 1977) which was the last major tectonothermal event in the region.Within the chiastolitic andalusite pseudo-morphs, equal proportions of margarite and sodic muscovite are separated from the rock matrix by a rim of coarser-grained muscovite, which has developed at the pseudomorph margins. A suggested reaction for the development of margarite is 10Al2SiO5+1.7Ca2++1.2K++Na++10H2O⇄(Ca1.6Na0.4)Al4(Si4Al4O20)(OH)3.6+(K1.2Na0.6Ca0.1)Al4(Si6Al20O20)(OH)4+6Al3++12.4OH−.The excess aluminium and hydroxyl ions from the above reaction leave the pseudomorph system but probably react with free quartz and more K+ ions to produce the muscovite fringe. 6SiO2+2K++6Al3++12OH−⇄K2Al4(Si6Al2O20)(OH)4+8H+.The above reactions are pertinent only for margarite and sodic muscovite produced by the pseudomorphism of chiastolitic andalusite.Margarite and sodic muscovite in the muscovite- chloritoid - sillimanite ± staurolite ± corundum rocks replace coarser-grained (up to 1 mm) muscovite, sillimanite, corundum, and chloritoid; staurolite is unaffected. The coarse muscovite of the earlier pseudomorphic assemblage contains 7–16 mole % paragonite in solid solution whereas the sodic muscovite assocated with margarite contains 22–33 mole% paragonite in solid solution. Margarite contains negligible muscovite but substantial (17–26 mole%) paragonite in solid solution. The phases plagioclase and paragonite were not detected in any of the investigated samples. Staurolite has an Mg/(Mg+Fe) value of 0.21 and associated chloritoid a value of 0.20.It is possible that much of the previously described sericitic alteration of andalusite (cf. D'arcy, 1977) within schists of the north-eastern Willyama Complex (north of Broken Hill) involves the production of margarite.
Girdite, oboyerite, fairbankite, and winstanleyite, four new tellurium minerals from Tombstone, Arizona
Authors: Williams S. A. 
Published: December 2006

SummaryGirdite, H2Pb3(TeO3)TeO6 is white, H = 2, D = 5.5. Crystals are complexly twinned and appear monoclinic domatic. The X-ray cell is a = 6.241Å, b = 5.686, c = 8.719, β = 91°41′; Z = 1.Oboyerite is H6Pb6(TeO3)3(TeO6)2 · 2H2O. H = 1.5, D = 6.4. Crystals appear to be triclinic but are too small for X-ray work.Fairbankite PbTeO3 is triclinic a = 7.81Å, b = 7.11, c = 6.96, α = 117°12′, β = 93°47′, γ = 93°24′, Z = 4. Indices are α = 2.29, β = 2.31, γ = 2.33.Winstanleyite, TiTe3O8, is cubic Ia3, a = 10.963Å. Crystals are cubes, sometimes modified by the octahedron; colour Chinese yellow, H = 4, nD = 2.34.All of the above species were found in small amounts on the waste dumps of the Grand Central mine, Tombstone, Arizona, associated with a wealth of other tellurites and tellurates.
Drugmanite, Pb2(Fe3+,Al) (PO4)2(OH) · H2O, a new mineral from Richelle, Belgium
Authors: Van Tassel R. , Fransolet A.-M. , Abraham K. 
Published: December 2006

SummaryDrugmanite occurs as rare colourless transparent platy crystals, up to 0.2 mm, aggregated in bunches, in vugs of a mineralized and silicified limestone. Hardness < 6. Crystals monoclinic, forms {001} {110}, parameters from indexed X-ray powder pattern (and monocrystal measurements): a = 11.110 (11.111) Å, b = 7.976 (7.986), c = 4.644 (4.643), β = 90°18′ (90°.41°). Space group P21/a with Z = 2 giving Dcalc = 5.55. Strongest lines are 4.63 Å (9), 3.752 (IO), 3.350 (8), 3.247 (8), 2.912 (9). Mean refractive index 1.88 from reflectance measurements. Strong dispersion r < v, optic axial plane // (olo), 2Vα = 33±2°. Electron microprobe analysis gave P 8.89, Al 0.85, Fe 6.19, Pb 59.76%, leading to Pb4.02
( Al0.45)P4.00O17.02·3H2O or Pb2(Al0.22) (PO4)2 (OH)·H2O. Associated minerals are pyromorphite, anglesite, corkite and phosphosiderite. Named for J. Drugman, Belgian mineralogist (1875–1950).
Tomichite, a new oxide mineral from Western Australia
Authors: Nickel E. H. , Grey I. E. 
Published: December 2006

SummaryTomichite, (V,Fe)4Ti3AsO13(OH), a new mineral species related to derbylite, has been found in the ‘green leader’ gold lodes at Kalgoorlie, Western Australia. It is monoclinic, with space group P21/m or P21; a = 7.119 (3), b = 14.176 (5), c = 4.992 (2) Å, β = 105.05 (I)°, Z = 2. Strongest diffraction lines: 3.092 (4), 2.836 (9), 2.663 (10), 1.572 (5). Tomichite occurs as tiny euhedral crystals in quartz; associated minerals are vanadian muscovite, rutile, pyrite, and calaverite. Tomichite is black, has a black streak, lacks internal reflections, is moderately anisotropic, and has S.G. = 4.16 (meas.), 4.42 (calc.). Reflectivity values are 470 nm-15.9%, 546 nm-16.3%, 589 nm 16.6%. Microhardness is VHN 800, using 50 g load.
Metasomatic reaction between acid pegmatite and orthopyroxenite at Currywongaun, Connemara, Ireland
Authors: Kanaris-Sotiriou R. , Angus N. S. 
Published: December 2006

SummaryLate-stage acid pegmatites veining the predominantly ultrabasic Currywongaun-Doughruagh intrusion are frequently associated with amphibole-rich reaction borders in the adjacent wall-rocks. The chemical and mineralogical changes resulting from reaction between an acid pegmatite vein and the orthopyroxenite wall-rock are assessed from chemical analyses of rocks and microprobe analyses of the amphiboles forming the zoned reaction border. The main chemical change was the addition of H2O to the wall-rock; otherwise the formation of the anthophyllite and hornblende of the reaction border from pyroxene was virtually isochemical. Enrichment in other chemical species, notably Ca and AI, was restricted to the region close to the interface between the reactants. This inhibited style of reaction is attributed to the initial marginal crystallization of the acid pegmatite melt acting as a barrier to subsequent metasomatic interchange.
A note on low-grade contact metamorphism—southwestern Brewster County, Texas
Authors: Droddy Marvin J. , Butler John C. 
Published: December 2006

SummaryIntrusion of the Bee Mountain soda microsyenite plug in southwestern Brewster County, Texas established conditions of low grade contact metamorphism in the upper Cretaceous Boquillas and Pen Formation sedimentary rocks. It is unlikely that load pressure exceeded 330 bars or that temperatures exceeded 470 °C at the intrusive contact. Thermally unaltered parent materials predominantly contain ortho- and allochemical low-magnesium calcite, silt-sized quartz, calcium montmorillonite, kaolinite, and volcanic glass. Incipient metamorphism is marked by the appearance of xanthophyllite followed by prehnite formed at the expense of xanthophyllite and montmorillonite. Near the soda microsyenite contact prehnite has decomposed to yield grossular and epidote group minerals, and apophyllite has replaced calcite where fluorine-bearing solutions have reacted with the parent material. Textural modifications include the recrystallization of calcite, redistribution of some of the mineral phases, and decreased friability in the marly layers.
Pyroxenes in altered volcanic rocks, Glenrock Station, NSW, Australia
Authors: Offler R. 
Published: December 2006

SummaryMicroprobe analyses of relict pyroxenes in meta-basalts from thrust slices of the Peel fault zone, Glenrock Station, NSW, demonstrate that the majority of these rocks have a tholeiitic affinity. Those of Ordovician to L. Devonian(?) age in the upper thrust slices show a greater Fe-enrichment, and lower wollastonite, Al and Ti contents than their Devonian counterparts in the lowest thrust sheet. The pyroxene data also indicate that some rocks are geochemically transitional between tholeiitic and alkaline magmas. The relict pyroxenes in metadolerites emplaced in the Devonian sequence show that these rocks are transitional to tholeiitic in character and that they appear not to be consanguineous with the metabasalts.
Two kinds of exsolution in chondritic olivine
Authors: Ashworth J. R. 
Published: December 2006

SummaryTransmission electron microscopy of several chondritic meteorites reveals exsolution products of two kinds in olivine. The coarser variety comprises particles that have nucleated heterogeneously on subgrain boundaries. Electron microprobe data confirm that these are chromite. The second variety, consisting of smaller precipitates distributed randomly, is interpreted as a homogeneously nucleated analogue of the first. It is potentially important as an indicator of cooling history. The aluminium-poor compositions of heterogeneously exsolved chromites suggest that some Cr may have entered tetrahedral sites in olivine during initial rapid crystallization from the melt.
Synthesis of prismatic and tabular diamond crystals
Authors: Kuge S. , Koizumi M. , Miyamoto Y. , Takubo H. , Kume S. 
Published: December 2006

SummaryWhen diamond is synthesized at conditions of comparatively high temperature and pressure, the nucleation rate is high, as is the growth rate of the nuclei. Consequently the product is usually an aggregate of crystals with dendritic or skeletal structure. In this study the presence of gold or silver as an additive mixed with a catalyst was found to have the effect of suppressing nucleation. When a homogeneous mixture of graphite, catalyst, and additive was treated at conditions where skeletons and dendrites were produced in the absence of additive, euhedral crystals of octahedra were formed. When a special cell assemblage for high pressure experiments, in which the graphite was placed inside a cylinder of catalyst coated with additive, was used, prismatic and tabular crystals were synthesized.
Mineralogy of vesicles in an olivine leucitite at Cosgrove, Victoria, Australia
Authors: Birch W. D. 
Published: December 2006

SummaryAn olivine-titanomagnetite-apatite-clinopyroxene-mica-nepheline-feldspar assemblage occurs in late-stage vesicles in a small outcrop of olivine leucitite at Cosgrove, Victoria. The vesicles were formed by exsolution of volatiles at an early stage in the cooling history of the lava. Subsequently, a volatile-rich residual liquid filled cavities and fractures, giving rise to a coarse-grained pegmatoid rock type similar in over-all mineralogy to the vesicles. The volatiles facilitating crystallization in both the vesicles and the pegmatoid were probably enriched in F, CO2, and P. A number of geothermometers applied to the vesicle assemblage failed to agree on likely crystallization temperatures.
Scarbroite, Al5(OH)13CO3·5H2O, compared with gibbsite and hydrotalcite
Authors: Brindley G. W. 
Published: December 2006

SummaryThe composition of scarbroite, written in the form Al5(OH)13CO3·5H2O, suggests close crystal-chemical relations to gibbsite and to hydrotalcite and kindred minerals. Parametral relations a(S) ≃ 2b(G) and 3b(S) ≃ 5a(G), S = scarbroite, G = gibbsite, are obtained and are consistent with a hydroxy Al layer structure and interlayer carbonate anions and water molecules. Thermal transformations show two discrete hydrated phases with layer spacings near 8.5 and 7.65 Å and a third phase with initial spacing 6.65 Å which decreases progressively to 5.5 Å over the temperature range 100°–250 °C as decomposition proceeds. No clear break is observed between dehydroxylation and decarbonation.
A new synthesis and characterization of magnesium-aluminium hydroxides
Authors: Mascolo G. , Marino O. 
Published: December 2006

SummaryA new synthesis of Mg-Al double hydroxides is described, that gives products relatively low (0.8–1.0%) in CO2. The general formula [Mg1−xAlx (OH)2][(OH)x(H2O)0.81−x] with 0.23 ≤ x ≤ 0.33 is proposed. Cell parameters and thermal data are given. The c-axial length decreases with Al-content; this is attributed to increased electrostatic attraction between layers.
Iron-titanium oxides as an indicator of the role of the fluid phase during the cooling of granites metamorphosed to granulite grade
Authors: Rollinson Hugh R. 
Published: December 2006

SummaryA detailed electron probe study of irontitanium oxide intergrowths from slowly cooled granitic rocks from the granulite grade, Archaean Scourian complex of north-west Scotland has yielded a wealth of information about magmatic and metamorphic temperatures, subsolidus cooling, and the behaviour of the fluid phase during cooling. Five stages are documented in the cooling history of granites and trondhjemites which include: (i) magmatic-subsolidus cooling (1035 °C–890 °C); (ii) granulite facies metamorphism and the accompanied expulsion of a hydrous fluid phase (890 °C–830 °C); (iii) subsolidus cooling following the peak of the granulite facies metamorphism (830 °C–660 °C); (iv) the localized reintroduction of water into the rocks during retrogression (660 °C–530 °C) and (v) subsolidus cooling and re-equilibration in the presence of a finite amount of H2O (530 °C–320 °C).
The effects of surface damage and oxide films on the optical properties of cuprite
Authors: Rastall P. , Clarke K. Mc. , Roberts E. F. I. 
Published: December 2006

SummarySpectral ellipsometry in the range 240 nm to 540 nm has been used to investigate the influence of surface damage induced by mechanical polishing and surface films of CuO on the optical properties of pure synthetic cuprite. Comparison is made between bulk CuO and thin film CuO produced by low-temperature oxidation of cuprite. The effects of strain and disorder are discussed in relation to the suppression of excitonic transitions. Recently developed techniques have been used to simplify the analysis and take full advantage of the spectral data.
Sinjarite, a new mineral from Iraq
Authors: Aljubouri Zeki A. , Aldabbagh Salim M. 
Published: December 2006

SummaryA hygroscopic, soft, pink mineral was discovered in Sinjar town, west of Mosul city. Wet chemical and X-ray diffraction analyses proved that the mineral has a composition of calcium chloride dihydrate CaCl2·2H2O, which has not been known in nature before. It is therefore a new mineral, and is named sinjarite after its locality.
Grandidierite from aluminous metasedimentary xenoliths within acid volcanics, a first record in Italy
Authors: van Bergen Manfred J. 
Published: December 2006

SummaryGrandidierite has been identified in two aluminous metasedimentary xenoliths from quartz-latitic volcanic rocks from Mt. Amiata and Mt. Cimino, central Italy. Physical and electron microprobe data for the grandidierites and petrological data for the grandidierite-bearing xenoliths are presented. The grandidierites formed by a reaction involving pre-existing aluminium rich minerals, possibly at temperatures of at least 800 °C and at low pressures. The grandidierite from Mt. Amiata replaces sillimanite. Several common characteristics can be demonstrated for magmatic and metamorphic grandidierite-bearing rocks. It is suggested that metamorphic rocks in which grandidierite occurs have often undergone partial melting.
X-ray diffraction and magnetic studies of altered ilmenite and pseudorutile
Authors: Wort M. J. , Jones M. P. 
Published: December 2006

SynopsisIT was not until 1966 that pseudorutile was first defined. Earlier, its X-ray diffraction spectrum had been confused with that of futile and, to a lesser degree, with those of hematite and ilmenite. Subsequent work has shown that pseudorutile has a world-wide distribution in detrital ilmenite-bearing heavy mineral deposits. The present work has confirmed its magnetic susceptibility and density. In addition pseudorutile is shown to be a magnetic spin glass with a peak susceptibility at 23 °K.Altered ilmenites, in which pseudorutile occurs as a secondary alteration product, display a range of chemical composition and magnetic susceptibility. The most highly magnetic fractions are not necessarily those containing the least-altered ilmenite, and in material from Capel, Western Australia, the most highly magnetic fractions were those containing grains of ferrimagnetic ferrian ilmenite.Quantitative X-ray diffraction has shown that West Australian altered ilmenite contains significant amounts of amorphous ilmenite, pseudorutile, and rutile. The magnetic susceptibility of paramagnetic fractions of altered ilmenite from Capel, Western Australia, can be calculated from normative compositions based on chemical analyses.
Volatile flux, geotherms, and the generation of the kimberlite-carbonatite-alkaline magma spectrum
Authors: Bailey D. K. 
Published: December 2006

SummaryA comparison of shield geotherms with the experimentally determined vapour-present solidus for kimberlite, indicates conditions of grazing incidence between 150–200 km, precisely where the mineral geotherms become disturbed. This relationship permits a new interpretation of kimberlite activity, by which volatiles migrating through cratonic lithosphere cause first metasomatism, and then incipient melting in the zone of incidence. Production of localized pockets of near-solidus liquid, erupted by accelerating crack propagation through the overlying lithosphere, is consistent with the unique set of features that characterize kimberlite. Volatile fluxing along steeper geotherms (away from craton nucleii) produces entirely different modes of magma eruption and development, by which highly under-saturated alkalic melts can reach the surface as liquids. Kimberlite activity is thus revealed as the limiting case of cratonic magmatism.
Kimberlite and kimberlitic intrusives of southeastern Australia
Authors: Ferguson John 
Published: December 2006

SummaryFifteen widely separated occurrences of kimberlite and kimberlitic rocks are now known in south-eastern Australia. Those that have been satisfactorily dated isotopically give ages ranging from Permian to Late Jurassic. One occurrence exhibits an intimate spatial association with carbonatite. The classification of these rocks as ‘kimberlitic’ is partly based on their mode of emplacement, and particularly on the presence of crust/mantle inclusions. Compared with African kimberlitic magmas, the southeastern Australian examples have lower incompatible-element contents. These differences are interpreted as representing slightly greater degrees of partial melting of a four-phase Iherzolite assemblage at shallower depths (∼ 65 km) than typical African kimberlite magma.