bluuebunny/crossref_metadata_2025_split huggingface dataset:
Uranium and thorium geochemistry in the elberton batholith of the Southern Appalachians, USA
Authors: Wenner David B. , Spaulding James D. 
Published: December 2006

AbstractU and Th data have been obtained by γ-ray spectrometry on samples from thirty quarry sites in the Elberton batholith, a large (500 km2) late orogenic (320 Ma) mesozonal biotite granite in the Southern Piedmont, USA. The granite is enriched in the Th (=42ppm), but U contents (=3ppm) are close to the average abundance for granites (18 ppm Th; 4 ppm U). Th/U ratios vary widely throughout the batholith, ranging from 3 to 58, with an unusually high mean of 18±10 (1). At some localities, lower Th/U ratios, high U contents of zircons (1500 ppm), and similarities to two-mica granites which have low Th/U ratios of ∼ 1 indicate that the granite once had a much higher U content. Pegmatites are enriched in U (up to a factor of 8), but Th contents are low (by a factor of 3) compared with the granite suggesting loss of U from the granite by an early magmatic vapour-phase. Significant U loss may also have occurred as a result of groundwater leaching, possibly associated with uplift and weathering of the intrusion 200 Ma ago. The highest Th/U values occur in the upper portions of the batholith, consistent with the hypothesis of U loss by these processes. The U content is highly variable throughout the batholith but Th is more uniform, both regionally and at outcrop. The distribution of Th does not correlate with patterns shown using previously published, 18O/16O, 87Sr/86Sr, or trace element (Ba, Rb. Sr, Mn) data, which are thought to reflect inhomogeneity in the protolith of the granite although the possibility that at least some of the isotopic ratios were disturbed by late alteration processes cannot be eliminated.
Geological setting and geochemistry of uranium-rich granites in the Proterozoic of Sweden
Authors: Wilson M. R. , Åkerblom G. V. 
Published: December 2006

AbstractUraniferous granites occur in several different geological settings in the Swedish Precambrian and represent a variety of granite types and ages. Granites with > 10 ppm U are highly differentiated leucocratic alkali granites with initial87Sr/86Sr ratios over 0.708. They commonly show enrichment in F, Sn, W, and/or Mo, while mineralization of these dements may, in some cases, be found in the nearby country rock. Radiogenic heat from the granites may have assisted hydrothermal circulation. In only one case, Hotagen, is important U mineralization thought to be directly related to a U-rich granite, while the majority of epigenetic U mineralizations with economic potential are related to hydrothermal processes in areas where the bedrock is regionally enhanced in U.
Some observations on todorokites from marine and terrestrial environments
Authors: Ostwald Joseph 
Published: December 2006

AbstractManganese nodules from the central Pacific contain poorly crystalline todorokite and also small amounts of a post-depositional recrystallization todorokite. The Cu and Ni of the nodules is preferentially concentrated in the latter. Crystalline todorokite on Groote Eylandt does not contain Cu or Ni, providing further evidence that these elements are not necessary to the development of well-crystalline todorokite.
New data for pitticite and a second occurrence of yukonite at Sterling Hill, New Jersey
Authors: Dunn Pete J. 
Published: December 2006

AbstractPitticite is re-examined analytically and found to be a gel-like mineral of widely varying composition. Previously reported minor amounts of accessory elements are indeed present in pitticite. The name pitticite has validity only as a generic name for gel-like ferric iron arsenate minerals of varying composition.Yukonite is reported from the Sterling Hill mine, Ogdensburg, New Jersey, the second occurrence. New data for yukonite suggest the name should be retained.
Ferromagnesian silicates in a differentiated alkaline complex: Kûngnât Fjeld, South Greenland
Authors: Stephenson D. , Upton B. G. J. 
Published: December 2006

AbstractKûngnât Fjeld is an intrusive complex resulting from three intrusive events involving trachyte, mafic trachyte and hawaiite magmas tapped successively from a single magmatic source. In situ differentiation produced gabbroic, syeno-gabbroic, syenitic, and quartz syenitic cumulates showing strong cryptic variation. Layered sequences of syenitic rocks total c. 3500 m. The compositional range is extended by late-stage minor intrusions of microsyenite and peralkaline granite. The principal cumulus minerals are feldspar (Ab40An60 to Or45Ab51An4); olivine (Fo56 to Fo1) and clinopyroxene (Di70Hd27Ac3 to Di6Hd90Ac4 followed by an abrupt change of trend towards Di3Hd78Ac19 in the layered series and nearly pure aegirine in some peralkaline residues). Intercumulus phases are amphibole (hastingsite to ferro-edenite to ferro-actinolite in the layered series with riebeckite to arfvedsonite in some associated granites) and biotite (annite31 to annite98.5).
Nature and origin of meladiorite layers in northern Guernsey, Channel Islands
Authors: Bishop A. C. , French W. J. 
Published: December 2006

AbstractThe Cadomian igneous complex of N. Guernsey includes gabbro, diorite, granodiorite, and adamellite. The gabbro is layered, shows variations in colour index and texture, contains abundant amphibole, and is cut by the diorites. The diorites show little variation in mineral compositions despite considerable variation in modal proportions. They contain numerous thin and roughly parallel veins of leucodiorite and granodiorite, and layers of meladiorite occur in several places within the veined diorites. These meladiorites, previously interpreted as separate intrusions, form individual layers from a few centimetres to several metres thick which can be traced for some tens of metres along strike. The upper surfaces of the meladiorites are planar but the lower tend to be indented and irregular. The layers thin out laterally and usually pass into the host diorite by way of a zone containing dark spots and both the spots and the meladiorite layers are composed of actinolitic hornblende and Mg-biotite.Chemical and petrographic data are presented for most of the rocks and minerals especially for the meladiorites and their host, the veined diorites. The rock chemistry and particularly the compositions of the amphiboles and micas of the meladiorites and the mafic spots, taken together with the presence of unmixing lamellae in the amphibole and the details of the field relationships, indicate that the rocks tended to equilibrium under subsolidus conditions and are most probably of metasomatic origin.Acid pipes and pegmatites occur within and are restricted to the meladiorites. The forms of the pipes were previously taken to indicate that they were magmatic at the same time as the meladiorites. The metasomatic origin for the meladiorites proposed here calls into question this magmatic interpretation and it is suggested that the pipe formation is connected with the metasomatic process. It is envisaged that the alteration of the veined diorites took place under conditions in which high gas pressures allowed acidic melt to be produced at temperatures only a little above the solidus of the diorites. The thermal impulse for this recrystallization may have resulted from the polyphase intrusive history of the complex as a whole.
A calcium-poor rhodonite from Xanthi (N. Greece)
Authors: Sapountzis Elias S. , Christofides George 
Published: December 2006

AbstractA Ca-poor rhodonite (CaO 1.31 wt.%), found in a quartz vein cutting manganese ore bodies, north of the Xanthi plutonic complex (northeastern Greece) was studied. Microprobe analyses with optical and physical properties are given. The cell dimensions, obtained by least squares calculation from direct θ value measurements on a Philips PW1100 single-crystal diffractometer are a = 7.626, b = 11.844, c = 6.702 Å, α = 92.44°, β = 94.28°, γ = 105.70°, V = 579.89 Å3, Z = 10, and space group P.
Dwornikite, (Ni,Fe)SO4 · H2O, a member of the kieserite group from Minasragra, Peru
Authors: Milton Charles , Evans Howard T. , Johnson Robert G. 
Published: December 2006

AbstractDwornikite, (Ni1−xFex)SO4 · H2O is a member of the kieserite group, monoclinic with space group C2/c. Specimens from Minasragra, Peru with x ∼ 0.1 have a unit cell with a = 6.839(2), b = 7.582(2), c = 7.474(2) Å, and β = 117.85(2)°. The six strongest lines of the powder pattern are: 3.342 (12, 100), 4.732 (110, 70), 3.024 (200, 70), 4.754 (11, 50), 3.293 (021, 35), 2.491 (022, 35). The mineral occurs as fine grained white aggregates associated with vanadium sulphide ores containing patronite and bravoite, mixed with other oxidation products. New unit cell data for the synthetic end-member compounds NiSO4 · H2O and FeSO4 · H2O, and new X-ray powder data for retgersite (NiSO4 · 6H2O) are provided.
Ardaite—a new lead-antimony chlorosulphosalt
Authors: Breskovska V. V. , Mozgova N. N. , Bortnikov N. S. , Gorshkov A. I. , Tsepin A. I. 
Published: December 2006

AbstractThe first occurrence of new mineral ardaite (a chlorine sulphosalt) has been discovered in the Madjarovo polymetallic ore deposit (Bulgaria). The average composition is Pb 56.50, Ag 0.04, Sb 22.48, S 15.56, Cl 3.78, total 98.36 wt.%. The formula is Pb20–18 Sb12–24S34–36.5Cl6–8. The mineral occurs as fine acicular aggregates associated with galena, nadorite, a Cl-bearing robinsonite and Cl-beating semseyite, pyrostilpnite, silver- bearing tetrahedrite and anglesite.
Luddenite, a new copper-lead silicate from Arizona
Authors: Williams S. A. 
Published: December 2006

AbstractFound at a small prospect in the Artillery Peaks area, Arizona. Luddcnite occurs in oxidized Cu-Zn ores with fluorite, alamosite, and cerussite. Colour nickel green, H = 4, G meas. 4.45.Strongest X-ray lines are 7.361(10), 3.173(10), 2.918(8), 5.218(7), 4.226(5), 3.411(5), 2.888(5), 3.650(4). A possible cell found by Ito method is a = 7.85, b = 20.06, c = 14.72 Å, β = 90.78° (monoclinic). Optically (+), α = 1.852, γ = 1.867.Chemical analysis by wet methods gave CuO 13.2%, PbO 35.1, SiO2 25.7, H2O 20.5, TiO2 (leucoxene impurity) 4.7. Not all water need be essential, hence Cu2Pb2Si5 O14·nH2O. The new mineral and name have been approved in advance of publication by the Commission on New Minerals and New Mineral Names, IMA.
Gobbinsite, a new zeolite mineral from Co. Antrim, N. Ireland
Authors: Nawaz Rab , Malone John F. 
Published: December 2006

AbstractA chalky white, fibrous mineral, in the amygdales of Tertiary basalts from the Gobbins area, Co. Antrim, has been discovered to be a new mineral. It consists of fibrous dusters of lath-shaped crystals showing straight extinction with negative elongation. Its refractive index is ɛ 1.489, ω 1.494 (both ± 0.003) and specific gravity is 2.194 (meas.), 2.147 (calc.). The mineral is tetragonal with ɛ = c (elongation); a = 10.145, c = 9.788 Å. The strongest powder lines (in Å, intensity in brackets) are: 7.10, 4.10, 3.19(100); 3.10, 2.69(80); 5.07(50); 2.64(40). A spectrographic analysis shows major Si, Al, minor Ca, Na, Cu, and trace Fe. Two chemical and one probe analysis give the ideal formula Na4(Ca,Mg,K2)Al6Si10 O32.12H2O. The name gobbinsite (approved by the IMA Commission on New Mineral Names) is suggested after the locality. The type specimen (I7881) is preserved in the Ulster Museum.Rotation and Weissenberg photographs of gobbinsite and garronite show doubled reflections, which are explained on the basis of submicroscopic twinning on (101). Relationship between gobbinsite and garronite is discussed and evidence is presented for the occurrence of minute amounts of a merlinoite-type mineral that forms regular intergrowths with gobbinsite and garronite.
Palladium minerals from Hope's Nose, Torquay, Devon
Authors: Clark A. M. , Criddle A. J. 
Published: December 2006

AbstractTwo palladium arsenide-antimonides have been found as small inclusions associated with native gold at Hope's Nose. One of the minerals has been identified as isomertieite; the other is chemically very similar to mertieite-II (Cabri et al., 1975). Electron probe microanalysis gives the formula of the isomertieite as (Pd10.89 Au0.08Cu0.03)Σ11.00(Sb2.01As1.99)Σ4.00 and of mertieite II as (Pd7.90Au0.07Cu0.01)Σ7.98(Sb2.43As0.59)Σ3.02. The relectance spectra of isomertieite in air and in oil at intervals of 10 nm from 400–700 nm are tabulated. The luminance values of the Hope's Nose isomertieite are 55.5 % in air and 42.5% in oil. The type specimen of isomertieite from Itabira, Minas Gerais, Brazil, has been re-examined; a new electron probe analysis is given and improved reflectance spectra are tabulated. The latter gives luminance values of 54.3% in air and 41.3% in oil.
The occurrence of pumpellyite in basic igneous rocks from the Coloured Series NE of Neyriz, Iran
Authors: Arvin M. 
Published: December 2006

AbstractThe occurrence of pumpellyite in Late Cretaceous volcanic rocks of the Coloured Series, NE of Neyriz, is reported for the first time. The form of the pumpellyite and its chemistry are described. The mineral assemblages of the prehnite-pumpellyite facies of metamorphism are present, indicating that burial metamorphism has occurred, a new factor to be considered in the tectonic evolution of the Zagros suture zone.
Microscopic rods in metallurgical slags
Authors: Wearing E. 
Published: December 2006

AbstractMicroscopic rods of wüstite and sulphide phases have been observed within silicate crystals from metallurgical slags. The rods, which are distinct from acicular crystals of accessory minerals, tend to be orientated perpendicular to the faces of the host crystal. These rods, and their constant orientation, are a product of the crystallization environment. It is proposed that they result from saturation of the melt with the relevant phase at the growth front of the silicate crystals. This microstructure is compared with known examples of microscopic rods and tubes in rocks.
A note on the occurrence of chevkinite, allanite, and zirkelite on St. Kilda, Scotland
Authors: Harding R. R. , Merriman R. J. , Nancarrow P. H. A. 
Published: December 2006

AbstractThe occurrence of three accessory minerals with significant rare earth contents in Tertiary acid rocks of St. Kilda is described. Allanite, zirkelite, and chevkinite were identified by electron probe analysis (with energy-dispersive attachment) and the chevkinite confirmed by X-ray diffraction. Brief comparison is made with other Tertiary occurrences of RE minerals. This is the first recorded occurrence of chevkinite in Great Britain.
New data for lansfordite
Authors: Hill R. J. , Canterford J. H. , Moyle F. J. 
Published: December 2006

AbstractEuhedral crystals of the low-temperature mineral lansfordite, MgCO3 · 5H2O, have been prepared from saturated magnesium bicarbonate solutions at temperatures below 10°C. The crystals are monoclinic P21/a with a = 12.4758(7), b = 7.6258(4), c = 7.3463(6)Å, β = 101.762(6)°, V = 684.24Å3, Dcalc. = 1.693 g cm−3, Dobs. = 1.70(1) g m−3. At room temperature, the crystals slowly effloresce to produce pseudomorphs of nesquehonite, MgCO3 · 3H2O. Dehydration is complete at 300°C, with decarbonation taking place in the interval to 560°C. A new X-ray powder diffraction pattern is presented, and details of the infra-red absorption spectrum are discussed.
The crystal structures of aluminosilicate-sodalites: X-ray diffraction studies and computer modelling
Authors: Beagley B. , Henderson C. M. B. , Taylor D. 
Published: December 2006

AbstractX-ray powder methods have been used to study the room-temperature structures of the synthetic sodalites: Li8(Al6Si6O24)Cl2, K7.6Na0.4(Al6Si6O24)Cl2, and Na8(Al6Si6O24)I2. Natural sodalite was also studied and the atomic coordinates show satisfactory agreement with those determined from the single-crystal data of Löns and Schulz (1967). The LiCl- and KCl- as well as the NaCl-sodalites refined in the expected sodalite space group P3n, but the NaI-sodalite fitted 13m better. The resulting structural data reveal shortcomings in the previous computer models for sodalite structures and an improved computer modelling procedure is devised which successfully predicts atomic coordinates, starting from the experimental a value and an estimate of the cationanion distance. The method incorporates the experimental result that the average T-O distance (T = Al, Si) throughout the samples is ∼ 1.678 Å, and Si-O and Al-O are set at 1.618 and 1.738 Å, respectively. Although T-O remains little changed throughout the samples, the data confirm the inverse relationship between ∠ T-O-T and the tetrahedron tilt angle ϕ, in which ∠ T-O-T approaches ∼ 160° as ϕ → 0° and the sodalite cage becomes fully expanded.
General comments on the identification of chlorites in thin sections
Authors: Saggerson E. P. , Turner L. M. 
Published: December 2006

AbstractAlthough a ‘chlorite’ is usually simple to recognize in thin section because of its characteristic colour, form, and often very low or anomalous interference colours, the identification of the various species is more difficult and requires both chemical and X-ray work for accurate determination. Roy and others have demonstrated that chlorites are polymorphous and occur in two structural groups, the normal 14 Å chlorites and the 7Å septechlorites (Nelson and Roy, 1958). Many chlorite varieties may be found in both structural states, low-temperature end-members and compositionally extreme end-members favouring the septechlorite structure, especially antigorite, amesite, chamosite, greenalite, and cronstedtite. Phillips (1964) subsequently proposed that six variables, Y, R3+, R2+ , Σ, H, plus the appropriate structural designation, must be fixed to define completely a variety of the chlorite group and from this he developed a numerical system of classification. Unfortunately these specific chemical and structural properties cannot be directly recognized by normal optical methods.
The primary ore mineralogy of the Alderley Edge deposit, Cheshire
Authors: Ixer R. A. , Vaughan D. J. 
Published: December 2006

AbstractThe Alderley Edge deposit, Cheshire, England has been mined principally for Cu and Pb. Here, veins and disseminations occur in coarse-grained clastic sediments of Triassic age and are classified as belonging to the red-bed type of mineralization.Examination of material in polished and thin section has shown the mineralization to be multiphase. The earliest opaque phases are associated with the diagenesis of the sandstones and include authigenic anatase, plus bravoite, pyrite, and chalcopyrite within authigenic quartz overgrowths. This stage of mineralization was followed by the formation of intergrown bravoite, pyrite, chalcopyrite, sphalerite, and galena accompanied by minor amounts of Ni-Co-Fe sulpharsenides, marcasite, and tetrahedrite cementing the clastic grains. This primary assemblage has undergone extensive alteration resulting in the formation of djurleite, covelline, and blaubleibender covelline accompanied by Pb and Zn carbonates and sulphates. Later, extensive shattering of the cemented clastic grains has been infilled by supergene Cu, Pb, and Zn carbonates and sulphates, limonite, and other secondary minerals.Electron probe microanalysis of the sulphides shows the pyrite to contain significant Ni and Cu but lesser amounts of Co; the sphalerite to be an Fe-poor variety but to contain Cd, and the chalcopyrite to contain Sb. Ag is present in appreciable amounts in tetrahedrite and occurs in trace amounts in both sphalerite and chalcopyrite but not in galena. The concentration of Ag increases with the alteration of the primary sulphides to secondary sulphides. This is most clearly demonstrated by the alteration of chalcopyrite to an idaite-like phase and finally to djurleite when the Ag content increases from 0.10 to 2.35 wt. %.
Thermal aspects of the origin of Hebridean Tertiary acid magmas. II. Experimental melting behaviour of the granites at 1 kbar PH20
Authors: Thompson R. N. 
Published: December 2006

AbstractExperimental melting equilibria at 1 kbar PH2O are reported for three early Tertiary granites from Skye and one from Rhum, together with a quartz monzonite from Ardnamurchan. The Hebridean Province leucogranites show cotectic melting behaviour, whilst associated ‘primitive’ (mostly adamellitic) acid plutons have silicate liquidi ∼ 925 °C and plagioclase liquidi ∼ 875 °C. At such high temperatures the morefusible crustal rock types of the region would be almost completely molten. If the Tertiary ‘primitive’ acid magmas were simple crustal melts, they would inherit the incompatible element ratios of their sialic progenitors. This is demonstrably not so. Minor element ratios in these plutons are consistent with extensive fractional crystallization during the evolution of their magmas. But it is, in most individual instances, extremely difficult to specify, either by thermal or geochemical arguments, whether (1) fractional crystallization followed sialic contamination of basic magmas or (2) mixing occurred between fractionation residua and sialic melts. Both the minor element ratios and cotectic melting behaviour of the Hebridean Province leucogranites are consistent with the view that they are products of extreme fractional crystallization of (sial contaminated) more-basic magmas. Nevertheless, it is clear—when the sequence and timing of emplacement of acid magmas within individual intrusive centres is considered—that very complex polycyclic combinations of fusion, fractionation, and re-fusion were involved in the evolution of these granites.The solidi of the samples studied experimentally, together with published data, show a progressive rise in temperature as the compositions of the rocks diverge from the minimum melting composition in NaAlSi3O8-KAlSi3O8-SiO2 at 1 kbarH2O. This relationship is important when considering the likely nature of sialic contamination of basic to intermediate continental magmatic suites fed through reservoir systems which are swarms of dykes and, or, sills. Because salic low-solidus crustal rock types also show near-cotectic melting behaviour, the composition of the contaminant may be strongly biased towards these (usually minor) crustal units, rather than the ‘bulk’ or average crustal composition.
The geology and geochemistry of the strathy complex of north-east Sutherland, Scotland
Authors: Moorhouse Valerie E. , Moorhouse Steven J. 
Published: December 2006

AbstractThe Strathy complex is a fault-bounded block of the sub-Moine succession basement characterized by a marked aeromagnetic anomaly. XRF analyses of 94 rocks for 26 elements are used to illustrate the geochemistry of the complex. It comprises siliceous grey gneisses (50 analyses), subordinate amphibolite (13 analyses), hornblende gneiss (13 analyses), and ultramafites (1 analysis), with scapolite-diopside marble and calc-silicate rocks (3 analyses from Strathy, 14 analyses of other calc-silicates). Geochemically the Strathy gneisses are quite distinct from the adjacent Moine lithologies, being unusually low in K, Rb, La, and Ce, and high in SiO2 and Na2O, whilst differences in immobile elements such as Ti and Zr preclude their derivation from a Moine source. The Strathy complex is unlike other high-grade gneiss terrains and apparently acquired its characteristic geochemical features by the removal of an anatectic melt under amphibolite-facies conditions leaving a refractory residue of quartz, plagioclase, Ca-poor amphibole, and garnet ± staurolite in siliceous gneisses. Subsequent influx of water, retrogression to biotite-bearing assemblages, production of sillimanite, and anateclic trondhjemitic melts took place during the maximum metamorphism of the surrounding Moine. The complex is considered to have originated as a dacitic supracrustal sequence with minor sediments and mafic-ultramafic intrusives. REE and Y abundances suggest a Proterozoic age, possibly as part of the Laxfordian cycle.