bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mineralogical nomenclature: pseudorutile revalidated and neotype given
Authors: Grey Ian E. , Watts John A. , Bayliss Peter 
Published: December 2006

AbstractPseudorutile, , has recently been revalidated as a mineral species, and the neotype locality is now South Neptune Island, South Australia. Powder X-ray diffraction data are given on a hexagonal primitive unit cell with a = 2.8667(5) and c = 4.5985(9) Å. Leucoxene, arizonite and proarizonite are considered to be mixtures. Kleberite is considered to be a hydroxylian pseudorutile, .
Zr-rich non metamict perrierite-(Ce) from holocrystalline ejecta in the Sabatini volcanic complex (Latium, Italy)
Authors: Parodi G. C. , Della Ventura G. , Mottana A. , Raudsepp M. 
Published: December 2006

AbstractThis paper reports the first in-situ finding of perrierite-(Ce) in Latium. The mineral occurs as brownish-red, transparent, well-developed, euhedral, prismatic crystals inside the miarolitic cavities of a holocrystalline ejectum from La Mola, Monti dell'Anguillara district, Sabatini volcanic complex.The cell parameters (from Gandolfi film) are (in Å): a = 13.629(9), b = 5.727(1), c = 11.715(6), β(°) = 113.74(2), V(Å3) = 835.5(9). The crystal-chemical formula, based on microprobe analysis of one grain, is:This perrierite is the most Zr-rich described so far. The entry of Zr in the C site of the structure is related to the substitution of large amounts of Ca in the A site, according to the charge balancing relationship:The genesis of perrierite-(Ce) from La Mola is linked to late pneumatolitic-pegmatitic hypabyssal stages of the regional volcanic activity.
Schwertmannite, a new iron oxyhydroxysulphate from Pyhäsalmi, Finland, and other localities
Authors: Bigham J. M. , Carlson L. , Murad E. 
Published: December 2006

AbstractSchwertmannite is a new oxyhydroxysulphate of iron from the Pyhäisalmi sulphide mine, Province of Oulu, Finland. It occurs there, and elsewhere, as an ochreous precipitate from acid, sulphate-rich waters. Associated minerals at other localities may include jarosite, natrojarosite, goethite and ferrihydrite. Schwertmannite is a poorly crystalline, yellowish brown mineral with a fibrous morphology under the electron microscope. A high specific surface area in the range of 100 to 200 m2/g, rapid dissolution in cold, 5 M HCl or in ammonium oxalate at pH 3, and pronounced X-ray diffraction line broadening are consistent with its poorly crystalline character.Colour parameters for the type specimen as related to CIE illuminant C are L* = 53.85, a* = + 15.93, and b* = +47.96. Chemical analysis gives Fe2O3, 62.6; SO3, 12.7; CO2, 1.5; H2O−, 10.2; H2O+, 12.9; total 99.9 wt.%. These data yield an empirical unit cell formula of Fe16O16(OH)9.6(SO4)3.2·10H2O after exclusion of CO2 and H2O−. The most general simplified formula is Fe16O16(OH)y(SO4)z·nH2O, where 16 − y = 2z and 2.0 ⩽ z ⩽ 3.5. Schwertmannite has a structure akin to that of akaganéite (nominally β-FeOOH) with a doubled c dimension. Its X-ray powder diffraction pattern consists of eight broad peaks [dobs in (Iobs) (hkl)] 4.86(37)(200,111); 3.39(46)(310); 2.55(100)(212); 2.28(23)(302); 1.95(12)(412); 1.66(21)(522); 1.51(24)(004); and 1.46(18)(204,542), giving a = 10.66(4), c = 6.04(1) Å, and V = 686(6) Å3 for a primitive, tetragonal unit cell. The probable space group is P4/m. Upon heating, schwertmannite transforms to hematite with Fe2(SO4)3 occurring as an intermediate phase. Bidentate bridging complexes between Fe and SO4 are apparent in infrared spectra. Mössbauer data show the Fe in schwertmannite to be exclusively trivalent and in octahedral coordination; it has a Néel temperature of 75 ± 5 K and a saturation magnetic hyperfine field of about 45.6 T. Pronounced asymmetry of the Mössbauer spectra indicates different locations for Fe atoms relative to SO4 groups in the structure. The name is for Udo Schwertmann, professor of soil science at the Technical University of Munich.
Mikasaite, (Fe3+, Al)2(SO4)3, a new ferric sulphate mineral from Mikasa city, Hokkaido, Japan
Authors: Miura Hiroyuki , Niida Kiyoaki , Hirama Tadao 
Published: December 2006

AbstractThe new ferric sulphate mineral, mikasaite, the Fe analogue of millosevichite was found in Ikushunbe tsu, Mikasa city, Hokkaido, Japan. Mikasaite occurs as a sublimate around fractures from which coal gas escapes. The white-light brown coloured mineral shows aggregates of fine porous crystals. The SEM micrographs indicate that the aggregates are hollow spherical crystals of 100 µm average diameter and 1–5 µm thickness. Microprobe analysis, SO3 by wet analysis and H2O by moisture evolution analyser gives Fe2O3 24.3, Al2O3 4.3, Mn2O3 0.5, SO3 46.8, H2O(−) 23.0, total = 98.9 wt.%. The specimen adsorbed a large amount of H2O on its surface because of its strong deliquescence. As H2O is not essential to the mikasaite structure, the empirical formula on the basis of 3SO4 is (Fe1.56Al0.44Mn0.03)Σ2.03(SO4)3.00, ideally Fe2(SO4)3. The strongest 10 lines in the X-ray powder diffraction patterns, indexed on a hexagonal unit cell are (d,I/Io,hkl): 3.56, 100, 113; 5.99, 28, 012; 4.35, 23, 104; 2.97, 20, 024; 2.72, 20, 116; 2.64, 11, 211; 2.35, 7, 300; 2.24, 6, 303; 1.78, 6, 226; 3.68, 5, 006. It has space group R with hexagonal lattice parameters of a= 8.14(1) and c = 21.99(8) Å.
The roedderite-chayesite series from Spanish lamproites: crystal-chemical characterization
Authors: Alietii E. , Brigatti M. F. , Capedri S. , Poppi L. 
Published: December 2006

AbstractMembers of the roedderite-chayesite series in lamproites from Cancarix (SE Spain), crystallized from late magmatic residua under low PH2O, high temperature (∼ 1100°C), oxidizing conditions. They exhibit the following main chemical variations: 0.14 ⩽ Na ⩽ 0.62 atoms per formula unit (apfu); 0.80 ⩽ K⩽ 1.00 apfu; 2.97 ⩽ Mg ⩽ 4.33 apfu; 0.00 ⩽ Fe2+ ⩽ 1.19 apfu; 0.42 ⩽ Fe3+ ⩽ 0.87 apfu; they are hexagonal (10.120 ⩽ a ⩽ 10.135 Å, 14.305 ⩽ c ⩽ 14.326 Å), P6/mcc. The characteristic chemical substitution is: Fe3+ + □ ⇌ Fe2+ + (K+Na)+. Six crystal structures have been refined to 0.020 ⩽ Robs ⩽ 0.026. They have the osumilite/milarite-type structure, with Si entering the double tetrahedral T1 six-membered rings, and Mg and Fe entering both the ring-linking T2 tetrahedra, and the A octahedra. The 12-coordinated C site, located between two double rings of T1 tetrahedra, is occupied mainly by K and subordinately by Na. Furthermore, Na occupies the partially empty nine-fold coordinated B site which occurs both in the ideal (z = 0) and in a split-atom position along the c direction.
Sugilite in manganese silicate rocks from the Hoskins mine and Woods mine, New South Wales, Australia
Authors: Kawachi Y. , Ashley P. M. , Vince D. , Goodwin M. 
Published: December 2006

AbstractSugilite relatively rich in manganese has been found at two new localities, the Hoskins and Woods mines in New South Wales, Australia. The occurrences are in manganese-rich silicate rocks of middle to upper greenschist facies (Hoskins mine) and hornblende hornfels facies (Woods mine). Coexisting minerals are members of the namansilite-aegirine and pectolite-serandite series, Mn-rich alkali amphiboles, alkali feldspar, braunite, rhodonite, tephroite, albite, microcline, norrishite, witherite, manganoan calcite, quartz, and several unidentified minerals. Woods mine sugilite is colour-zoned with pale mauve cores and colourless rims, whereas Hoskins mine sugilite is only weakly colour-zoned and pink to mauve. Within single samples, the chemical compositions of sugilite from both localities show wide ranges in Al contents and less variable ranges of Fe and Mn, similar to trends in sugilite from other localities. The refractive indices and cell dimensions tend to show systematic increases progressing from Al-rich to Fe-Mn-rich. The formation of the sugilite is controlled by the high alkali (especially Li) and manganese contents of the country rock, reflected in the occurrences of coexisting high alkali- and manganese-bearing minerals, and by high fo2 conditions.
Image analysis of petrographic textures and fabrics using semivariance
Authors: Swan Andrew R. H. , Garratt Jane A. 
Published: December 2006

AbstractMany subjective descriptive terms such as ‘smooth’, ‘coarse’ and ‘anisotropic’ are routinely used to convey properties of textures and fabrics, but these aspects of geological objects are not easily quantifiable. The use of directional semivariograms of image greylevels is assessed for this purpose. These quantify anisotropy of ‘coarseness/fineness’ by using semivariogram ranges, and ‘roughness/smoothness’ by using semivariogram sill values. These can be summarized by ellipses derived from semivariogram ranges and directions. The method will find applications in analysis of rock thin sections as well as analysis of surface texture of grains and microfossils.
The interpretation of granitic textures from serial thin sectioning, image analysis and three-dimensional reconstruction
Authors: Bryon D. N. , Atherton M. P. , Hunter R. H. 
Published: December 2006

AbstractTextural development of the felsic phases in two granodioritic rocks from the zoned Linga superunit of the Peruvian Coastal Batholith has been characterized using serial thin sectioning, image analysis and three-dimensional reconstruction. The study has shown how each mineral phase contributed to the texture during the formation and development of a contiguous crystal framework and during subsequent restriction, isolation and occlusion of the melt-filled porosity. The work highlights the important factors and potential problems in the use of serial thin sections and imaging in the analysis of complex polyphase rock textures.
Precision serial lapping, imaging and three-dimensional reconstruction of minus-cement and post-cementation intergranular pore-systems in the Penrith Sandstone of north-western England
Authors: Cooper Mark R. , Hunter Robert H. 
Published: December 2006

AbstractThe application of serial lapping, imaging and image processing, and three-dimensional reconstruction techniques are discussed using the quartz-cemented Penrith Sandstone as an example. The study involves the characterization of the three-dimensional pore system microgeometry using combined back-scattered scanning electron and cathodoluminescence microscopy and focuses on the definition of post-compaction and post-cementation intergranular porosity networks. Sample preparation, section spacing and re-orientation and data presentation are described. Aspects of the application of serial section datasets and their limitations are discussed in relation to permeability studies.
A new procedure for relocating mineral grains for microprobe analysis
Authors: Potts P. J. , Tindle A. G. , Stanford D. 
Published: December 2006

AbstractA new procedure is described for locating mineral grains in geological samples prepared for microprobe analysis. This procedure uses a digital image of the entire sample surface to select points of interest. These features of interest must be visible in this external image. Once the sample is mounted on the specimen stage of the microprobe, the digital image is used as a ‘map’ to relocate minerals for analysis. The image can be recorded using either a video camera, fitted with a macro zoom lens, or a flat-bed scanner. A calibration procedure has been developed in which two indexing points are used to calculate the instrument stage coordinates from the pixel coordinates of the digital image. Following this calibration, the stage coordinates of any feature visible in the digital image can be displayed to facilitate rapid relocation. The procedure was evaluated by relocating magnetite grains visible in an optical image of a geological thin section. The repositioning accuracy in relocating 28 magnetite grains distributed over an area of about 20 × 30 mm was found to be 157 ± 102 µm (one standard deviation) from the video camera image and 48 ± 28 µm from a flat bed scanner image. The former image was thought to suffer from some optical distortion. The procedure may be applied to any microprobe instrument fitted with a digital x-y specimen stage. Future applications in relocating features visible in autoradiographs are currently being evaluated.
Genesis of chemical sediments in Birimian greenstone belts: evidence from gondites and related manganese-bearing rocks from Northern Ghana
Authors: Melcher Frank 
Published: December 2006

AbstractEarly Proterozoic chemical sediments of the Birimian Supergroup in northern Ghana host several types of metamorphosed manganese-bearing rocks. Differences in the mineralogy and geochemistry can be attributed to facies changes in a mixed volcanic-volcaniclastic depositional environment. Manganese oxide-bearing phyllite, which is enriched in transition metals (Cu, Ni, Co, Zn), formed on the flanks of submarine volcanic edifices above an oxidation boundary. Towards the deeper basin, manganese silicate-rich gondites occur. These consist either of spessartine + quartz + ilmenite, or of spessartine + quartz + Mn amphiboles ± rhodonite ± hyalophane ± Mn stilpnomelane ± ilmenite. The Mn amphiboles are identified as manganoan actinolite, tirodite, and dannemorite. Sulphides are widespread as premetamorphic inclusions in Mn garnet grains. In the basin centre, chlorite schist containing garnet with 50–60 mol.% spessartine represents the most distal manganese-bearing rock which is highly diluted by volcanogenic background sedimentation. The origin of Mn-rich rocks is explained by heat-driven seawater convection systems active in submarine volcanic centres that provided hydrothermal solutions. Precipitation of different minerals depended on the geochemical conditions prevailing on the seafloor. During the Eburnean event (around 2000 Ma), the chemical sediments were metamorphosed to upper greenschist or lower amphibolite facies. Mineral assemblages in the gondites point to metamorphic conditions in the range of 450–500°C at 2–3 kbar.
Deposition and transport of gold by thiosulphates, Veitsch, Austria
Authors: Kucha H. , Prohaska W. , Stumpfl E. F. 
Published: December 2006

AbstractTwo types of gold can be distinguished in tetrahedrite from the Veitsch magnesite deposit, Austria. Primary gold present in unfractured massive tetrahedrite, has a grain size up to 18 μm and contains, on average, Cu 8.73, Ag 7.01, Au 78.63 and Hg 2.35 (wt.%). Secondary gold is present in fractures and is directly intergrown with digenite, covellite, Cu-thiosulphate, cuprite and chrysocolla but not with malachite or azurite. The secondary gold is up to 200 µm in size with an average composition of Cu 3.06, Ag 6.82, Au 86.41 and Hg 3.51 (wt.%). It is usually closely intergrown with thiosulphates containing up to 0.21 wt.% Au. This, together with the presence of ‘dirty’ gold with cloudy thiosulphate inclusions, directly indicates the transport and deposition of Au by a thiosulphate ligand. We believe this is the first reported direct evidence of gold transport and deposition by thiosulphate complexes in a natural environment.
A fusion method for preparing glass samples of peridotitic and picritic rock compositions for bulk analysis
Authors: Odling N. W. A. 
Published: December 2006

AbstractA design for a micro furnace and a fusion technique are described by which silicate materials (in particular picritic and peridotitic rock compositions) may be fused and quenched to a homogeneous glass without significant loss of components, for the purposes of bulk analysis. The furnace consists of a Pt wire electrical resistance heater mounted in a furnace assembly which is fitted to a microscope stage. Microscopic examination of the sample during the fusion process allows the sample to be quenched as soon as all crystalline material has been fused and thus minimizes the loss of iron and alkalis due either to over-heating or prolonged fusion time. Analysis of glass beads of a model peridotite composition (analysed independently by X-ray fluorescence analysis) shows that for typical fusion times (5–10 seconds) the bulk composition is preserved at distances of > 25 µm from the margins of the glass beads. Analysis of natural rock powders of known composition shows that the method can be used to analyse whole rock compositions. The furnace is simple to construct and cheap to run and provides a simple and rapid method of producing glass samples for bulk analysis.
Enclaves and their bearing on the origin of the Cornubian batholith, southwest England
Authors: Stimac James A. , Clark Alan H. , Chen Yanshao , Garcia Sammy 
Published: December 2006

AbstractEnclaves of diverse origin are present in minor amounts in the coarse-grained biotite granites of the Cornubian batholith, southwest England. The most common enclave type is layered, rich in biotite, cordierite and aluminosilicates, and has textures and compositions that reveal variable degrees of melt extraction from metasedimentary source rocks. Rare sillimanite-bearing enclaves represent residual material, either from the region of magma generation or its ascent path, but most such enclaves were probably derived from the contact aureole closer to the present level of exposure. These non-igneous enclaves (NIE) and their disaggregation products are present in all major plutons, comprising from < 2 to 5 vol.% of the granites. Enclaves of igneous origin are also present in all major plutons except Carnmenellis, generally comprising < 1 vol.% of the granites. The most common type is intermediate in composition, with microgranular texture, and mineral compositions and textures consistent with an origin by magma mixing. Large crystals of K-feldspar, plagioclase and quartz, common in these microgranular enclaves (ME) but absent in NIE, represent phenocrysts derived from the silicic end-member during magma mixing events rather than products of metasomatism as suggested previously. Although the composition of the mafic end-member (basaltic or lamprophyric) involved in the mixing process is poorly constrained, the presence of ME in the granites, and the preponderance of mantle-derived mafic rocks in the coeval Exeter Volcanics, indicate that mafic magma injection into the crust was a factor in the generation of the batholith. Advection of sub-crustal heat provides an explanation for large-volume crustal melting in regions of relatively thin crust such as southwest England.
Shannonite, Pb2OCO3, a new mineral from the Grand Reef Mine, Graham County, Arizona, USA
Authors: Roberts A. C. , Stirling J. A. R. , Carpenter G. J. C. , Criddle A. J. , Jones G. C. , Birkett T. C. , Birch W. D. 
Published: December 2006

AbstractShannonite, ideally Pb2OCO3, is a new mineral species that occurs as mm-sized white porcellanous crusts, associated with fluorite, at the Grand Reef mine, Graham County, Arizona, USA. Other associated minerals are plumbojarosite, hematite, Mn-oxides, muscovite-2M1, quartz, litharge, massicot, hydrocerussite, minium, and unnamed PbCO3·2PbO. Shannonite is orthorhombic, space group P21221 or P212121, with unit-cell parameters (refined from X-ray powder data): a 9.294(3), b 9.000(3), c 5.133(2) Å, V 429.3(3) Å3, a:b:c 1.0327:1:0.5703, Z = 4. The strongest five lines in the X-ray powder pattern [d in Å (I)(hkl)] are: 4.02(40)(111); 3.215(100)(211); 3.181(90)(121); 2.858(40)(130); 2.564(35)(002). The average of eight electron microprobe analyses is PbO 89.9(5), CO2 (by CHN elemental analyser) 9.70, total 99.60 wt.%. With O = 4, the empirical formula is Pb1.91C1.05O4.00. The calculated density for the empirical formula is 7.31 and for the idealized formula is 7.59 g/cm3. In reflected light, shannonite is colourless-grey to white, with ubiquitous white internal reflections (× 16 objectives), weak anisotropy, barely detectable bireflectance, and no evidence of pleochroism. The calculated refractive index (at 590 nm) is 2.09. Measured reflectance values in air and in oil (× 4 objectives) are tabulated. Transmission electron-microscopy studies reveal that individual crystallites range in size from 10–400 nm, are platy, and are anhedral. Physical properties for cryptocrystalline crusts include: white streak; waxy lustre; opaque; nonfluorescent under both long- and short-wave ultraviolet light; uneven fracture; brittle; VHN100 97 (range 93–100); calculated Mohs’ hardness 3–3½. Shannonite is soluble in concentrated HCl and in dilute HNO3 and H2SO4. The mineral name is for David M. Shannon, who helped collect the samples and who initiated this study.
Stable coexistence of grandidierite and kornerupine during medium pressure granulite facies metamorphism
Authors: Carson C. J. , Hand M. , Dirks P. H. G. M. 
Published: December 2006

AbstractPetrological and mineral chemical data are presented for two new occurrences of co-existing borosilicate minerals in the Larsemann Hills, East Antarctica. The assemblages contain kornerupine and the rare borosilicate, grandidierite (Mg,Fe)A13BSiO9. Two distinct associations occur: (1) At McCarthy Point, 1–10 mm thick tourmaline-kornerupine-grandidierite layers are hosted within quartzofeldspathic gneiss; and (2) Seal Cove, where coexisting kornerupine and grandidierite occur within coarse-grained, metamorphic segregations with Mg-rich cores of cordierite-garnet-spinel-biotite-ilmenite and variably developed plagioclase halos. The segregations are hosted within biotite-bearing, plagio-feldspathic gneiss. Textural relationships from these localities indicate the stability of co-existing kornerupine and grandidierite.The grandidierite- and kornerupine-bearing segregations from Seal Cove largely postdate structures developed during a crustal thickening event (D2) which was coeval with peak metamorphism. At McCarthy Point, grandidierite, kornerupine and late-tourmaline growth predates, or is synchronous, with F3 fold structures developed during a extensive granulite grade, normal shearing event (D3) which occurred prior to, and synchronous with, near-isothermal decompression. Average pressure calculations on assemblages that coexist with the borosilicates at Seal Cove, indicate the prevailing conditions were 5.2–5.5 kbar at ∼ 750°C for formation of the grandidierite-kornerupine assemblage.
Mineralogy of a unique graphite-containing fragment in the Krymka chondrite (LL3)
Authors: Semenenko V. P. , Girich A. L. 
Published: December 2006

AbstractThe Krymka chondrite contains an exotic graphite-bearing fragment that appears to be of a new type of material added to unequilibrated LL-chondrite during agglomeration on the surface of the parent body. The fine-granular texture without chondrules, two morphological groups of graphite crystals which differ in size and occurence, high content of troilite (11.3 vol.%), the high Ni (55.5–66.6 wt.%) and Co (1.59–2.87 wt.%) contents of the taenite and absence of kamacite, the presence of F-apatite, which is rare for meteorites but common for lunar and terrestrial igneous rocks, are the main features of the fragment.The mineralogy and texture indicate: (1) the fragment probably formed by crystallization from a highly reduced silicate melt, which had been enriched in carbon; 2) the subsequent metal sulphidization lowered its abundance and resulted in the formation of troilite and the compositional features of the residual metal; (3) terrestrial weathering of an exotic fragment and the host part of the chondrite produced iron hydroxides, pentlandite and quite possibly magnetite.
Tungusite: new data, relationship with gyrolite and structural model
Authors: Ferraris Giovanni , Pavese Alessandro , Soboleva Svetlana V. 
Published: December 2006

AbstractNew chemical analyses, electron and X-ray powder diffraction data, and comparison with gyrolite and reyerite show that tungusite has the ideal formula , symmetry P and a = 9.714(9), b = 9.721(9), c = 22.09(3), α = 90.13(1)°, β = 98.3(2)°, γ = 120.0(1)°, Z = 1. A structural model for tungusite is derived by splitting the double tetrahedral layer of reyerite and inserting a trioctahedral X sheet which is ideally occupied by Fe2+. Polytypism phenomena due to different relative positions between tetrahedral and X sheets are discussed. A substitutional solid solution represented by the formula [Ca14(OH)8]Si24−yAlyO60[NaxM9−(x+z)□z(OH)14−(x+y+2z)·(x+y+2z)H2O] includes tungusite (x = y = z = 0, M = Fe2+ and gyrolite (x = 1, y = 1, z = 6, M = Ca).