bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tin-rich garnet, pyroxene, and spinel from a slag
Authors: Butler B. C. M. 
Published: December 2006

SummaryGarnet containing up to 26% SnO2, and pyroxene and spinel containing 12% and 10% SnO2 respectively, occur in a tin-refining slag in association with cassiterite. These tin contents probably represent minimum values for the limit of ionic replacement of Sn4+ in the structure of these minerals. The absence of tin from coexisting melilite suggests that Sn4+ is only able to substitute for ions in octahedral co-ordination.
The Dhajala meteorite
Authors: Das Gupta S. P. , Sen Gupta P. R. , Dube A. , Sen Gupta N. R. , Das Gupta D. R. 
Published: December 2006

SummaryThe Dhajala meteorite shower, the latest recorded fall in India, comprises pieces fragmented near the lower limit of the break-up zone. The meteorite is a chondrite consisting of silica-rich chondrules making up to 34 vol.%, and fine-grained, Fe-Ni metal-rich groundmass admixed with a few irregular lithic fragments. Dhajala contains olivine of variable compositions, ortho- and clinopyroxenes, troilite, kamacite, taenite, chromite, and clear to opaque glass; magnetite occurs only in the fusion crust. The chondrules, which are of variable shape, mineral composition, and texture, represent different stages of quenching, leading to incomplete crystallization of minerals and some degree of disparity between norm and mode. Lithophile elements are less in Dhajala than in average chondrites. Two chemical analyses of Dhajala are presented and it has 27·10% total iron and 2·38 % sulphur (maximum). Chemical and petrological data indicate that it is an H3 olivine-bronzite chondrite. Evidence for the crystallization of chondrules from melt is overwhelming. Some chondrules have been permeated by later troilite and NiFe from the groundmass, which might have crystallized directly from a gaseous environment.
A microscope-mounted drill to isolate microgram quantities of mineral material from thin and polished sections
Authors: Verschure R. H. 
Published: December 2006

SummarySeveral types of microscope-mounted drills have been described in literature to obtain pure mineral material from thin sections or polished sections (e.g. Granigg, 1915; Moritz, 1929; Haycock, 1931; Russanow, 1937; Machairas, 1967), but all of them appear to be of limited mechanical stability and reliability. This paper describes an improved drill to extract under the microscope minute quantities of pure material from thin or polished sections. The drilling is performed in a liquid (silicon-oil) to minimize loss of the drilled-out mineral powder. With the help of a micromanipulator the liquid, together with the borings, is drawn up into a microcapillary tube (less than 30 µm in diameter) made of Lindemann glass. For identification of the mineral powder the microcapillary is mounted in a Debye-Scherrer X-ray diffraction camera.
Paragenesis of hydrothermal mineralization in amphibolites and granulites around Porthkerris Point, the Lizard, Cornwall
Authors: Seager A. F. 
Published: December 2006

A study of the post-metamorphic hydrothermal mineralization in the gabbros of the Lizard has already been published (Seager, 1971). The present paper extends the investigation of mineralization in the peninsula to an adjacent area, on the NE. coast around Porthkerris Point. Table 1 gives the more important events of the paragenesis. Calcite and adularia are the only common minerals; all others are scarce or rare.The calcite that precedes and succeeds adularia is called early calcite and late calcite, respectively. Both early and late calcite occur in several generations differing in habit, fluorescence, and phosphorescence.
Rajite, naturally occurring cupric pyrotellurite, a new mineral
Authors: Williams S. A. 
Published: December 2006

SummaryRajite was found at Lone Pine, New Mexico, by R. A. Jenkins. It occurs as small (1.5 mm) crystals in rhyolite with mackayite, and may be a pseudomorph after teineite. Analysis gave CuO 18.4, 15.3, 18.0; TeO2 73.7, 79.8, 79.1; rem. (respectively) 7.9, 2.4, 2.3. Some CaO in samples 2 and 3: 2.5, 0.6%. This gives CuTe2O5, identical to the artificial compound prepared by Moret et al. (1969). Easily soluble in dilute acids; readily fusible.Monoclinic P21/c with a = 6.866 Å, b = 9.314, c = 7.598, β = 109.1°. Strongest lines 3.064(10), 4.654(8), 3.348(8), 3.111(7), 2.744(7), 3.793(6B), 2.844(5), 2.796(5). With Z = 4, ρcalc = 5.77 g/cm3.Crystals Duesbury green (RHS-131D), H = 4, ρmeas = 5.75 g/cm3. Pleochroic in greens γ > β > α; α = 2.115, β = 2.135, ‖ [010], γ = 2.26, α:[001] 22° in obtuse β, 2Vγ = 40°.
Kleemanite, a new zinc aluminium phosphate
Authors: Pilkington E. S. , Segnit E. R. , Watts J. , Francis G. 
Published: December 2006

SummaryA new hydrated zinc aluminium phosphate mineral has the composition ZnAl2(PO4)2(OH)2.3H2O. It has been named kleemanite. It occurred rarely both as veinlets 1–2 mm thick, and as thin layers on surfaces of cracks and small cavities in one section of the iron ore deposit at Iron Knob, South Australia. Chemical, X-ray, thermal analysis, and optical data are given.
Georgeite, a new amorphous copper carbonate from the Carr Boyd Mine, Western Australia
Authors: Bridge P. J. , Just J. , Hey M. H. 
Published: December 2006

SummaryGeorgeite, an amorphous copper carbonatehydrate, has been found in the oxidation zone of the Carr Boyd nickel deposit, Western Australia. It forms thin coatings mostly associated with malachite and chalconatronite on partly weathered tremolite rock containing disseminated copper and iron sulphides.Physical properties: Colour light blue, streak pale blue, lustre vitreous to earthy, fracture conchoidal, soft, sp. gr. 2.55; transparent to sub-opaque (aggregates), n(NaD) = 1.593, isotropic. Amorphous to X-rays and electron beam.Chemical microanalysis gave (wt%) CuO 54.9, ZnO 0.4, Na2O 2.7, CO2 20.8, H2O 21.7, sum 100.5. After deduction of all Na2O and corresponding amounts of CuO, CO2, and H2O as chalconatronite (12.35 wt%) the atomic ratios correspond to an empirical formula (Cu5.0, Zn0.05)(CO3)3(OH)4.12.6.3H2O, the ideal formula being Cu5(CO3)3(OH)4.6H2O.
Mineralization at Seathwaite Tam, near Coniston, English Lake District: The first occurrence of wittichenite in Great Britain
Authors: Stanley C. J. , Criddle A. J. 
Published: December 2006

SummaryOre specimens from the abandoned copper mine at Seathwaite Tarn, Cumbria, were studied in polished section by reflected light microscopy. The mineral paragenesis is described and related to current views on Lake District ore genesis. A common origin with the neighbouring deposit at Coniston is proposed. Wittichenite was identified in the ore, and is the first authenticated occurrence in Great Britain.
Almandine pseudomorphous after plagioclase in a metadolerite dyke from the Jotunheim, Norway
Authors: Battey M. H. , Davison W. , Oakley P. J. 
Published: December 2006

SummaryAn undeformed metadolerite dyke cutting foliated pyroxene-granulite facies gneisses in the Jotunhelm, Norway, has almandine rods replacing the cores of plagioclase laths, although garnet is generally absent from the enclosing gneisses, and is not present in reaction zones between peridotites and gneisses. Chemical analyses of the dyke and its garnet, plagioclase, and clinopyroxene are given. The presence of garnet in the dyke is attributed to the low mg ratio of the rock. The nature of the reaction leading to garnet pseudomorphous after plagioclase is discussed.
Definitive data on bohdanowiczite, a new silver bismuth selenide
Authors: Banaś M. , Atkin D. , Bowles J. F. W. , Simpson P. R. 
Published: December 2006

SummaryBohdanowiczite was first described in 1967 but incomplete data prevented its acceptance as a new mineral at that time. Additional data on the same material now characterize bohdanowiczite as a new species with the formula:3[(Ag0.98Cu0.02)0.97(Bi0.97Pb0.03)1.02(Se0.83S0.17)2.01]The mineral occurs in intimate intergrowths with clausthalite and wittichenite in polymetallic mineralization at Kletno in Poland. In reflected light bohdanowiczite has a creamy-yellow colour and short polysynthetic twinning is frequently observed. Cell parameters indexed on a hexagonal lattice are a = 4.183±0.008 Å and c = 19.561± 0.016 Å. Pm1 is the most likely space group. The strongest lines of the powder pattern are 2.91(100), 2.03(30), 3.40(20), 6.54(20), 2.09(18), 3.26(18). The calculated density is 7.72 gm/cm3 and the VHN between 63 and 96 kg/mm2.
Serpentine minerals from veins in serpentinite rocks
Authors: Morandi N. , Felice G. 
Published: December 2006

SummaryCrystal-chemical analyses of the serpentine polymorphs, sampled from macroscopic veins in the serpentinite rocks from Sasso della Mantesca and Sasso di S. Zanobi, are reported. The samples were examined by X-ray diffraction, thermal analysis (TG and DTG), scanning and transmission electron microscopy, IR absorption spectroscopy, microprobe, and chemical tests.The results show: chrysotile 2Orc1 in tubular fibrils placed perpendicularly to walls of iso-oriented ‘lenticular veins’; and polygonal serpentine formed by flat layers of lizardite 2H and/or 1T, arranged as an outer shell of a central core of chrysotile 2Mc1 fibres; this type of serpentine with high crystallinity and unusual morphological development is included in ‘green veins’, which show variable Al, Fe, and Mg contents.A genetic mechanism correlating the petrographic observations with the mineralogical results is discussed.
The effect of aluminium on the infra-red spectra of 7 Å trioctahedral minerals
Authors: Serna Carlos J. , White Joe L. , Velde Bruce N. 
Published: December 2006

SummaryThe substitution of 2A13+ for Si4+ +M2+ (M = Mg or Ni) has been studied by infra-red spectroscopy in 7 Å trioctahedral minerals over the composition range from Al = 0.00 to Al = 2.00. Significant differences are observed in the infra-red spectra and these make possible an estimation of the amount of Al in tetrahedral coordination. The most striking effect of the substitution is observed in the stretching vibrations of the outer hydroxyl groups and that of the silicate anion.The aluminous Mg-serpentines can be readily distinguished from their analogues, the aluminous Niserpentines, by the absence of the Mg-OH absorption band between 570 and 615 cm−1 in the latter.
Distribution of Fe and Mg between garnet and biotite in Scottish Barrovian metamorphic zones
Authors: Baltatzis E. 
Published: December 2006

SummaryThe distribution coefficient KD = (Mg/ Fe)garnet/(Mg/Fe)biotite has been calculated for eight garnet-biotite pairs from rocks ranging from the garnet isograd to the staurolite zone along the Stonehaven coast of NE Scotland. This distribution coefficient depends upon metamorphic temperature and is not dependent upon the Mn and Ca content of garnet. Garnet-biotite geothermometer yields temperatures of about 500, 550, and 575–620°C for the garnet, chloritoid + staurolite, and staurolite zones respectively.
Geochemical aspects of the Santonian Chalk of Ramsgate, England, and the origin of the chert and clay minerals
Authors: Spears D. A. 
Published: December 2006

SummaryThe mineralogy and major-element geochemistry of thirty-seven samples from a borehole in the Upper Cretaceous Chalk (Santonian) of Kent has been determined. The mean carbonate content is 97% and the carbonate is a low-Mg calcite (0.42 mol % MgCO3). Most of the silica is deduced to be biogenic chert. The total clay content probably varies through the sequence due to changes in the rate of carbonate sedimentation. The clay composition remains relatively constant with smectite more abundant than illite. The smectite and K-feldspar could be formed from volcanic debris whereas illite and quartz are thought to be detrital.
Topaz occurrence in Mardan, north-west Pakistan
Authors: Jan M. Qasim 
Published: December 2006

SynopsisColourless, purple, and pink topaz and transparent quartz crystals have been found in calcite veins (with or without milky quartz) in calcareous rocks near Katlang (34° 24′ N, 72° 6′ E), Mardan district. The veins do not contain any fluorite nor the country rocks any topaz. The topaz and transparent quartz crystals are mostly broken and perfectly euhedral outlines are very rare. Refractive indices, 2V, specific gravity, and the fluorine (determined) and H2O + (calculated) contents of two topaz crystals are suggestive of their high 100 OH/(OH+F) ratios (> 25). Rather than being derived, the topaz may have formed in situ by hydrothermal/pneumatolytic activity, followed by tectonic movements that fractured the crystals and resulted in their incorporation in later-formed vein calcite.
Alluaudites, wyllieites, arrojadites: crystal chemistry and nomenclature
Authors: Moore Paul B. , Ito Jun 
Published: December 2006

SynopsisA nomenclature is proposed for the alluaudite and wyllieite complex series which is based on sequentially distributing the cations in the cell according to increasing polyhedral size, matching that size with increasing ionic radii of the cations. For oxidized members, the largest site may be partly occupied to empty after all the cations have been distributed. This is supported by structural study.For alluaudites, the cell formula is X(2)4X(I)4 M(I)4M(2)8(PO4)12 and is written according to decreasing size of the discrete sites. The X(I) and X(2) sites are appended as suffixes in the trivial nomenclature, that is specific name—X(I)X(2).For wyllieites, the cell formula is X(2)4X (1a)2X(1b)2M(I)4M(2a)4A14(PO4)12. The X(1a), X(1b), and X(2) sites are appended as suffixes in the trivial nomenclature, that is specific name--X(la) X(Ib)X(2).The nomenclature proposed is:Seventeen analyses are discussed (of which five are new) for alluaudite and four analyses (of which three are new) for wyllieites. Their distribution is given parenthetically above. One analysis revealed predominant Mg2+ in M(2). It is named maghagen-dortite.Six new analyses are presented for the arrojadite family of minerals including re-examination of dickinsonite from Branchville, Connecticut. Al3+ is always present. We propose X1 Al (OH,F)(PO4)12, Z = 4, where X = large cations (K+, Ba2+, Pb2+, etc.), Y = Na1+, Ca2+, and M = Fe2+ Mn2+, Mg2+. A range of cations X, Y, M, and Al between 76.8 and 85.9 in the cell (84 for proposed formula) suggests the likelihood of some vacancies in the structure.
The blue coloration in banded fluorite (Blue John) from Castleton, Derbyshire, England
Authors: Galwey A. K. , Jones K. A. , Reed R. , Dollimore D. 
Published: December 2006

SummaryFrom the microscopic examination of lightly etched, cleaved (111) surfaces of banded blue fluorite (Blue John, from Castleton, Derbyshire) it is concluded that the coloured lamellae are not necessarily or exclusively associated with lattice-line imperfections. Elemental analyses, by electron dispersive methods, of fresh cleavage (111) surfaces in the immediate vicinity of small inclusions (c. 10 µm diameter) possessing associated coloured haloes detected no appreciable concentrations of impurities. From the evidence available, it is suggested that the zones of blue colour consist of colloidal calcium resulting from radiation damage caused by the intermittent deposition of radioactive material on the surfaces of fluorite during crystal development. The dispersion of colloidal calcium produced is particularly stable as a consequence of the close correspondence between lattice spacings in calcium fluoride and in calcium metal.
Electron petrography of high-temperature oxidation in olivine from the Rhum Layered Intrusion
Authors: Putnis A. 
Published: December 2006

SummaryElectron-microscope observations of the oxidation products of olivine suggest that oxidation results in the formation ofplatelets of an ‘oxidized olivine’ phase, which has a superstructure of the olivine structure. Subsequently this intermediate phase breaks down by a cellular decomposition process to a eutectoidal intergrowth of magnetite and pyroxene. This intergrowth is responsible for the dendritic magnetite inclusions commonly observed in some olivines from Rhum.
The development of porous microstructures during the dehydration of boehmite
Authors: Wilson S. J. 
Published: December 2006

SummaryElectron-microscope observations have been used to follow the low-temperature dehydration of boehmite, and show that a coherent skeleton of γ-Al2O3 with a porous texture is produced. For material fired in air the development of a number of pore systems is described. Of these the most important, as far as the dehydration process is concerned, is a lamellar pore system parallel to (001)γ and having a regular spacing of the order of 35–40. Å. A much faster dehydration process is induced by exposure to the electron beam and results in the formation of a more randomly oriented pore structure. The observed microstructure and the calculated internal surface area are compared with the results of previous adsorption studies.
Coexisting pyroxenes from spinel pyroxenites from the Eastern Ghats of Andhra Pradesh, India
Authors: Rao A. T. , Raman C. V. , Appa Rao G. 
Published: December 2006

SynopsisAnalyses are given of four pairs of coexisting pyroxenes; theirKpranges from 1.282 to 1.369, suggesting equilibration temperatures as high as 1200 °C and pressures of the order of 8 to 9 kb.
MacFallite and orientite: calcium manganese (III) silicates from upper Michigan
Authors: Moore Paul B. , Ito Jun , Steele Ian M. 
Published: December 2006

SummaryMacFallite, Ca2(Mn3+,Al)3(OH)3[SiO4] [Si2O7], is a new species occurring with manganite, braunite, orientite and pyrolusite blebs, stringers, and framboidal aggregates, which replace calcite in fissures and lenses in Keweenaw basalt near Manganese Lake, Copper Harbor, Keweenaw County, Michigan. It is rich reddish brown to maroon in coarse aggregates; compact massive material is brown to dull pink. The streak and powder are brown with a reddish tint. Lustre silky to subadamantine, specific gravity 3.43(2), hardness 5+, cleavage {001} perfect; twinning by reflection on {100} is universal. The mineral is monoclinic, space group P21, or P21/m, Z = 2, a 8.929(6), b 6.045(5), c 10.905(7) Å, β 119.10(3)°, α 1.773(5), β 1.795(5), γ 1.815(5), sign + or −, pleochroism α yellow, β light brown, γ dark brown, γ‖b. Orientite, Ca2Mn 2+ (OH)4[Si3O10]-Ca2 (OH)2[Si3O10] ·2H2O, orthorhombic, space group Cc2m, Ccm21or Ccmm, a 9.042(4), b 6.090(2), c 18.990(7) Å, α 1.765(5), β 1.79(1), γ 1.81(1), sign + or −, α brownish yellow, β reddish brown, γ deep brownish red, α‖a, γ‖b, also occurs in moderate abundance. It is turbid chocolate brown in platy masses but crystals are transparent rich reddish brown. Streak and powder brown. Observed forms are m{110}, c{001}, and poorly developed to absent α{100}, thin to thick tabular parallel to {001}, cleavage (or parting) {001} perfect, specific gravity 3.33.A fumarolic origin is proposed for the assemblage, which in many respects is similar to the great manganese oxide deposits in Oriente Province, Cuba. Macfallite appears to be structurally related to pumpellyite while orientite is apparently related to ardennite.
Two new occurrences and the Gibbs energy of burkeite
Authors: Vergouwen Lideke 
Published: December 2006

SummaryBurkeite (Na6CO3(SO4)2) is found as a surface mineral in the north of Kenya associated with thenardite and halite and in the Konya basin in Turkey associated with trona and halite. The cell dimensions of a natural burkeite are a = 7.070, b = 9.220, c = 5.173 Å. The Gibbs energy of burkeite is estimated in relation to other sodium carbonates and sulphates. Δ (burkeite) = 3594.2 ± 3 kJ.
Mössbauer spectra of goethite: evidence for structural imperfections
Authors: Murad Enver 
Published: December 2006

SummaryGoethites of well-crystallized appearance from a sedimentary ore deposit have been studied by Mössbauer spectroscopy and other methods following HCl corrosion, particle size fractionation, and annealing treatments.The goethites contained an appreciable amount of Si, but were not significantly Al-substituted. The observed broad and asymmetric resonant lines of the Mössbauer spectra are considered to result from this Si which, interspersed in the goethite structure, would interrupt magnetic coupling and give rise to a reduced and inhomogeneous magnetic hyperfine field.
High-temperature pyroxenes from an ironstone at Scourie, Sutherland
Authors: Barnicoat A. C. , O'Hara M. J. 
Published: December 2006

SummaryThe coexistence of clinopyroxene (Wo18 En32 Fs44 Rh06) and pigeonite (W08 En35 Fs50 Rh07) in a meta-ironstone from Scourie is described. By comparison with experimental data, the temperature at which they were in equilibrium is estimated as at least 1000°C. The exsolution history of the two pyroxenes is documented. As the rock is an unambiguous metasediment, its presence among granulite facies rocks containing evidence of metamorphism at pressures greater than 10 kbar constrains at least part of the Scourie complex to a supracrustal origin and indicates that tectonic processes of burial were operative in the late Archaean.
Oxygen isotope fractionation between rutile and water and geothermometry of metamorphic eclogites
Authors: Matthews Alan , Beckinsale Robert D. , Durham John J. 
Published: December 2006

SummaryOxygen isotope fractionation between rutile and water has been studied from 300 °C to 700 °C, PH2O = 1 kb, using aqueous oxidation of titanium metal as the equilibration reaction. The mechanism of rutile formation (which is critical to the assessment of isotopic equilibrium) is an ‘armouring’ reaction in which rutile grows around grains of titanium metal by solution-precipitation processes. Mean fractionation factors expressed as 103 In αTiO2-H2O obtained in the present study are:−6.20±0.23‰ at 304±5 °C−6.64±0.27‰ at 405±6 °C−6.11±0.16%. at 508±6 °C−4.45±0.28%. at 608±6 °C−3.38±0.15%. at 698±6 °C.These data agree with those obtained at temperatures above 500 °C by Addy and Garlick (1974) but do not accord with theoretical predictions by Bottinga and Javoy (1973). A minimum in the calibration curve 103 ln α versus 106T−2 occurs between 300 °C and 500 °C but from 500 °C to 700 °C 18O fractionation between rutile and water may be expressed by the equation:103 ln α = −(4.72±0.40)106T−2+(1.62±0.53).Oxygen isotope analyses of rutile and quartz from metamorphic eclogites and schists from the Tauern Window, Austria, yield isotopic temperatures at about 550 °C in agreement with results obtained on similar rocks from the Sesia Zone (Western Alps, Italy) and elsewhere by other workers. Petrologic studies indicate that the latest metamorphism of the Tauern eclogites reached about 450 °C Thus the measured partitions of 18O between rutile and quartz indicating temperatures around 550 °C have been inherited from an earlier metamorphic event.