bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calcium sulphosilicate in lime-kiln wall
coating
Authors: Pryce M. W. 
Published: December 2006

Summary
Green calcium sulphosilicate layers were
formed in lime-larnite-calcite wall coating in a
lime kiln at Rivervale, Western Australia. The
compound formed in the kiln flame area by the
combination of siliceous lime sand feed with
sulphur trioxide from the sulphurous oil
fuel.
The calcium sulphosilicate is orthorhombic
with a 10·183,
b 15·408,
c 6·825 Å, space group
Pcmn. Crystals are
[100] tablets or prisms elongated along
c, D 2·95, hardness 5,
streak pale green, decomposed by organic acids.
Optical properties α
1·632 = [001] blue, β
1·638 = [100] yellow-green
γ 1·640 yellow-green,
2Vα = 60°, dispersion
r >
v, X-ray powder lines:
2·855 (10) 032,202; 2·838 (7) 330,321; 3·35 (6)
012; 2·622 (6) 331; 2·571 (6) 060; 3·20 (5) 231;
1·962 (5); 1·899 (5); 1·896 (5); 1·372
(5).
Chemical analysis by P. Hewson gave:
SiO2 21·50,
Al2O3
1·83,
Fe2O2
0·50, CO2 0·49,
P2O5
0·23, CaO 57·19, MgO 0·35,
Na2O 0·22,
K2O 0·22, SrO 0·15,
Li2O 0·06,
SO3 16·71,
H2O+
0·28,
H2O−
0·10, others 0·04, total 99·87. On a water-free
basis the unit cell contains
Ca19.66
Mg0.17
Na0.14
K0.08
Sr0.03
Li0.08
approximately
4[Ca5(SiO4)2SO4]
and isostructural with silicocarnotite,
4[Ca5(PO4)2SiO4].
Type material is preserved at the Government
Chemical Laboratories, Perth, Western
Australia.
Wroewolfeite, a new copper sulphate hydroxide hydrate
Authors: Dunn Pete J. , Rouse Roland C. 
Published: December 2006

SummaryWroewolfeite is a new mineral from the Loudville lead mine in Loudville, Massachusetts, U.S.A. The mineral occurs as blue, monoclinic crystals, twinned on {001}, very similar in appearance to posnjakite and langite. It is formed as small isolated pinacoidal crystals (up to 1.0 mm) implanted on covelline and chalcosine. There are three cleavages of equal facility of production. The cell dimensions are a 6.058 Å, b 5.654 Å, c 14.360 Å, β 93° 28′, space group Pc or P2/c. The strongest diffraction lines (in Å) are 7.152 (100), 3.581 (70), 2.628 (35), 2.004 (30), 2.431 (20), 2.379 (20), 2.278 (20). Electronmicroprobe analysis gives CuO 64.22 %, SO3 16.48 %, water by difference 19.30 %. Empirical cell contents are Cu7.88(SO4)2.00(OH)11.76.(H2O)4.22 or Cu4(SO4)(OH)6.2H2O with Z = 2. Wroewolfeite is strongly pleochroic with a light blue, β deep greenish blue, and γ, medium greenish blue. Absorption β > γ ≫ α. The mineral is biaxial with α 1.637, β 1.682, and γ 1.694, 2Vα = 53° The name is for C. Wroe Wolfe, American crystallographer, educator, and philosopher.
Petrogenesis of the Tarr albitite—carbonatite complex, Sinai Peninsula
Authors: Shimron Aryeh Ervin 
Published: December 2006

SummaryLarge albitite bodies associated with explosive brecciation, fenite aureoles, intrusive carbonate rocks, olivine dolerites, and copper mineralization are described from the Dead Sea rift region in the south-eastern Sinai Peninsula. The main carbonate phases comprise breunnerite and dolomite with actinolite the main phase in the fenites. Field and isotopic evidence indicates that the intrusive carbonate rocks are of carbonatitic origin. The cogenetic, almost monomineralic main phases can be attributed to fractional crystallization and liquid immiscibility acting on a highly gascharged, slow-cooling gabbroic magma. The complex, which is probably of Cretaceous (or older) age, appears to be related to early continental separation along the Dead Sea branch of the African rift system. The porphyry-type copper deposits resemble others that are located along crustal accretion (Iceland) or subduction (Chile) zones.
Mercury in rocks and minerals of the Skaergaard intrusion, East Greenland
Authors: Dissanayake C. B. , Vincent E. A. 
Published: December 2006

SummaryMercury has been determined by radiochemical neutron-activation analysis in nineteen representative rocks from the Skaergaard intrusion and in the separated cumulus minerals of five. The chilled marginal gabbro contains 0.23 ppm Hg, values in the Layered Series rocks ranging from 0.07 to 0.34 ppm, in one exceptional case reaching 1.23 ppm Hg. There is a tendency for mercury to be more abundant in leucocratic than in average or melanocratic rocks at a similar horizon. Somewhat higher levels of mercury are found in the granophyric rocks at the top of the intrusion.Apart from a weak and sporadic tendency to be preferentially enriched in plagioclase, the distribution of mercury between the various cumulus phases is fairly uniform and it is thought to occur as uncharged atoms mainly occupying spaces resulting from lattice defects and imperfections rather than in specific structural sites.The distribution pattern of mercury in the intrusion appears to be determined by its high volatility and chemical inertness; no real evidence of any chalcophile character is observed.
Some aluminous clinopyroxenes from Vesuvius and Monte Somma, Italy
Authors: Rahman S. 
Published: December 2006

SummaryAluminous Ca-rich clinopyroxenes (5.95-7.63 wt % Al2O3) are next in abundance to leucite in the basic alkaline potassic lavas from Monte Somma and Vesuvius, Italy, and occur as phenocrysts (1 to 7 mm), micropbenocrysts (< 1 mm), and groundmass granules. Zoning of various types is a conspicuous feature in these pyroxenes. Optical and chemical data are presented and a comparison is made between these pyroxenes and similar ones from alkali basalts. It is known from published data that Al2O3 fluctuates strongly in the oscillatory zones of Vesuvian pyroxenes. This can be explained as due to temperature variation in the magma, to magma variation in silica content due to contamination, to oscillations in leucite precipitation, or to a combination of these factors. Of these three factors, oscillations in leucite precipitation, as it appears, would be more effective than the others since it would have a greater control over Si/A1 availability in the magma.
Garnets from the Upper Swat Hornblendic Group, Swat District, Pakistan. Part I: Garnets from gneisses and pegmatites
Authors: Ahmed Zulfiqar , Ahmed Shafeeq 
Published: December 2006

SummaryChemical analyses of eleven garnets from orthogneisses and related pegmatites, belonging to the Upper Swat Hornblendic Group, Pakistan, are presented along with the petrographic descriptions of the host rocks. The garnets show dominant almandine content, followed by grossular pyrope, spessartine, and andradite, in order of relative abundance. One garnet sample is different from the rest in having higher andradite and spessartine contents and higher refractive index, and is also different in habit. This is the first detailed study of garnets from Pakistan.
High-temperature homogenization behaviour of some sodic mieroperthites
Authors: Parsons Ian 
Published: December 2006

SummaryWhile undergoing 'dry' homogenization at 980°C the 2̄01 X-ray reflections of sodic lowalbite- microcline microperthites show that phase compositions recapitulate (but in a reverse timesense) the unmixing history of ordered feldspars about a solvus with a critical composition near 26 mole per cent KAlSi3O8.
A garnierite with a high nickel content from Western Australia
Authors: Nickel E. H. , Bridge P. J. 
Published: December 2006

SummaryThe garnierite, which occurs in the oxide zone overlying a nickel sulphide deposit, consists of talc-like and serpentine-like components, with the former predominating. Chemical and electron-probe analyses give NiO contents ranging between 39.6 and 43.9 weight %.
Volatility of oxides from silicate melt and the origin of moldavites
Authors: Konta J. , MráZ L. 
Published: December 2006

SummaryThe volatilities of SiO2, Na2O, and Fe2O31increase with increasing thermal function within the range 1600 to 2100°C during the melting of a sandy-silty clay. The remaining melt is to some extent enriched in Al2O3, K2O, CaO, and MgO. Chemical analyses of the sandy-silty clay, of the glasses melted from the latter, of the silicate material evaporated and newly condensed and their correlation with increasing thermal function and bulk density of glasses, as well as with the hitherto known quantitative data on moldavites, testify to the fact that in moldavites evaporated and newly condensed silicate material substantially prevails over material that passed directly from a solid to a fluid state. Evaporation of the silicate material from the rocks of the impact crater caused a significant change in relations between major oxides compared to the original relations in the source rocks. Thus, the hypothesis that tektites are directly remelted rocks of the Earth's crust, based on over-all chemical similarities of tektites and some rocks in major oxides, appears incorrect.
A Mössbauer study of thermal decomposition of biotites
Authors: Hogg C. S. , Meads R. E. 
Published: December 2006

SummaryThe effect of heat treatment in air at temperatures from 200°C to 1000°C of two Cornish biotites has been studied using the M6ssbauer effect in 57Fe. One of the micas was also studied after heating in vacuo.Progressive changes in the Mössbauer spectra of the materials after heat treatment can be correlated with the following processes: Oxidation of Fe2+ ions in isolated octahedral sites to give Fe3+ in the co-ordination Fe3+(OsOH); oxidation of Fe2+ ions in adjacent a-octahedral (cis OH−) sites to give Fe3+(O6); and oxidation of Fe z+ in adjacent a and b (trans OH−) sites to give either Fe3+(O5OH) or Fe3+(O6) depending on whether a shared hydroxyl group remains intact or otherwise (these processes occur at temperatures below 500°C Also, at higher temperatures, dehydroxylation of Fe3+(O5OH) to give more Fe3+ in the Fe3+(O6) configuration. Finally, in the temperature range 900 to 1000°C structural breakdown yielding α-Fe2O3 as the iron-containing phase.The results and interpretation are in good agreement with thermogravimetric data and with a previous infra-red study. The mechanism of charge diffusion in the lattice during oxidation is discussed in the light of the results.
A new miniphotometer for teaching and routine work in ore microscopy
Authors: Tarkian M. , Stumpfl E. F. , Matthies H. 
Published: December 2006

SummaryA simple and easy-to-use miniphotometer has been designed; the expense involved amounts to only a fraction of that required for large commercially available microphotometers.The instrument can be employed for routine investigations and for teaching reflected light microscopy in conjunction with standard reflected light microscopes.The reflectance of grains down to 50 μm size can be measured in white and monochromatic light employing continuous band and line interference filters. The systematic error does not exceed 1.5 % of the values measured. The only aspect that distinguishes the miniphotometer from larger instruments is the limitation of spot size. A comprehensive test programme including comparative sets of measurements on a Zeiss MPM spectral microphotometer has shown that the results obtained by both instruments coincide well.
Tacharanite
Authors: Cliff G. , Gard J. A. , Lorimer G. W. , Taylor H. F. W. 
Published: December 2006

SummaryTacharanite has been re-examined using electron microscopy and diffraction, analytical microscopy, X-ray powder and fibre rotation photographs, and other methods. The composition approximates to Ca12Al2Si18O69H36, and the X-ray diffraction patterns can be referred to anA-centred monoclinic pseudo-cell witha17·07,b3·65, c 27·9 Å, β 114·1°, Z = 1. In the true cellbis certainly, andaand c probably, doubled. Small, reversible changes in pseudo-cell parameters occur on heating below 200°C, and parameters found by electron diffraction differ slightly from those found with X-rays, presumably due to shrinkage on dehydration in the high vacuum of the electron microscope. An earlier report that tacharanite changes into a mixture of tobermorite and gyrolite on standing in air is not confirmed. Tacharanite shows some important resemblances to tobermorite, but there are also significant differences.
Chromite alteration in the Panton Sill, East Kimberley Region, Western Australia
Authors: Hamlyn Paul R. 
Published: December 2006

SummaryIn addition to the normal type of chromite alteration, an antipathetic form of alteration has been observed in the ultramafic zone of the Panton Sill, Western Australia. The chromites display margins of lower reflectivity related to a marked enrichment in MgO and Al2O3and depletion in Cr2O3, Fe2O3, and FeO, such that a spinellid of composition lying between the end members MgAl2O4and FeAlaO4is formed. The alteration is related to the formation of secondary spinel in the ground-mass during the hornblendization of primary silicates under metasomatic conditions accompanied by low oxygen activity.
Kaersutite-bearing gabbroic inclusions and the late dike swarm of Kangerdlugssuaq, East Greenland
Authors: Kent Brooks C. , Platt R. G. 
Published: December 2006

SummaryThe Kangerdlugssuaq late dike swarm, which strikes at a high angle to the well-known East Greenland coastal swarm, is described and chemical analyses presented. The basic members are characterized by a high potassium content. A variety of kaersutite-bearing gabbroic inclusions in one member of this swarm is described in detail and microprobe analyses of clinopyroxenes, amphiboles, plagioclases, sheet silicates, and spinel minerals are presented. On the basis of this evidence it is deduced that these inclusions derive from a cumulate sequence formed at depths of between 5 and 10 km beneath the Lower Tertiary land surface. It is likely that fractionation of such assemblages causes a transition, at relatively low pressure, from undersaturated to oversaturated compositions, but the products appear to be quantitatively minor.
Regional variation in the crustal abundance of minor elements: evidence from the granites of Sardinia
Authors: Hall A. 
Published: December 2006

SummaryThe granites of Sardinia have been analysed for copper, lead, and zinc, and each element has been found to show a regional variation. There is a close relationship between the copper and lead contents of the granites and the distribution of copper and lead mineralization in the island, but very little relation between the zinc contents of the granites and the distribution of zinc mineralization. This is attributed to a greater degree of lithophile character of zinc in the magmatic source region.
A sapphirine-cordierite-bronzite-phlogopite paragenesis from Namaqualand, South Africa
Authors: Clifford T. N. , Stumpfl E. F. , McIver J. R. 
Published: December 2006

SummaryThe rock composition and electron microprobe analyses of the five constituent minerals are presented for a sapphirine-cordierite-bronzite-phlogopite-spinel rock from Namaqualand, South Africa. These data are considered inrelation to experimental data and the mineralogy of certain associated rock types, and it is suggested that the sapphirine-bearing rock represents a metamorphic residuum (restite) after extraction of anatectic granitic liquid from an original argillaceous sediment.
The origin of the Kennethmont granite-diorite series, Insch, Aberdeenshire
Authors: Busrewil M. T. , Pankhurst R. J. , Wadsworth W. J. 
Published: December 2006

SummaryThe Insch granite-diorite complex of Aberdeenshire consists of acid and intermediate igneous rocks that are quite distinct from, and younger than, the differentiates of the Insch basic mass.The main components of the complex include two types of uniform granite (one pink, one grey), and a variety of inhomogeneous dioritic rocks (diorite xenoliths in grey granite matrix, granodiorite with residual mafic inclusions, and more uniform diorite). Full chemical analyses for major and trace elements are presented for sixteen rocks representative of all types, together with initial 87Sr/86Sr ratios and rare-earth-element distribution patterns for a selection of samples. The pink granite is not chemically related to the remaining members of the complex. Comparison with chemical data for a range of basic igneous rocks of the Insch and Boganclogh basic masses discredits the hypothesis that the diorite rocks were produced by assimilation of any of these in the grey granite magma. A primary diorite magma is recognized as essential to the petrogenesis of the complex.
Leucite-Na-feldspar incompatibility: an experimental study
Authors: Gupta Alok K. , Edgar Alan D. 
Published: December 2006

SummaryPhase relations at atmospheric pressure in the pseudobinary join KAlSi2O6 (Lc)-NaAlSi3O8(Ab) and in the pseudoternary join Lc-Ab-CaAl2Si2O8(An) indicate that leucite is in-compatible with Na-feldspar. In the former join leucite can exist with an alkali feldspar of maximum albite content Ab54. In the Lc-Ab-An join, leucite only coexists with ternary feldspars with high An contents (approximately An50). Under PH2O conditions leucites may only coexist with alkali feldspars even poorer in Ab than those found at atmospheric pressure. Rare occurrences of coexisting leucite and Na-feldspar in nature have probably not crystallized directly from a melt but may have formed by a process of alkali ion exchange; or they may be unstable assemblages. No support can be found for the suggestions based on thermochemical calculations that albite and leucite are compatible at high temperatures.
Mineralogy, chemistry, and origin of a concretionary siderite sheet (clay-ironstone band) in the Westphalian of Yorkshire
Authors: Curtis C. D. , Pearson M. J. , Somogyi V. A. 
Published: December 2006

SummaryConcretionary siderite horizons are quite common in massive clay sequences. One such horizon, from the Westphalian of Yorkshire, has been studied in detail. Two iron-rich carbonate minerals occur together although they cannot be distinguished in thin section on account of very fine grain size. One is much richer in magnesium (pistomesite) than the other (siderite). The latter is rela-tively rich in manganese and the heavier stable carbon isotope 13C whereas the former carbonate is richer in calcium and 12C. The most important iron source is thought to have been hydrated iron oxides originating in soils. Much of the carbonate carbon started as organic molecules. The siderite appears to have formed earlier than the pistomesite. The stratiform character of these deposits appears to reflect siltier horizons in the mudstones, which presumably channelled pore water migration during compaction. This is probably why such carbonate horizons were formerly believed to be of simple sedimentary rather than diagenetic origin.
On 'winchite' from the original locality at Kajlidongri, India
Authors: Nayak V. K. , Leake Bernard E. 
Published: December 2006

SummaryA new analysis of the violet amphibole from the original locality where winchite came from agrees with another recent analysis in differing substantially from the original winchite composition and is (K0·17Na2·10Ca0·23)(Al0·19Ti0·00Fe31·27Fe20·01Mn0·07Mg3·34)Si8·01O22·05(OH)1·95. It is essentially a magnesio-arfvedsonite. Although it is possible that the original analysis was unreliable, evidence is given to support the alternative view that there is a wide range of blue alkali and soda calcic amphibole compositions at Kajlidongri and the name winchite should be restricted to compositions between ferri-winchite CaNaMg5Fe3+Si8O22(OH,F,Cl)2 and alumino-winchite CaNaMg5Al Si8O22(OH,F,Cl)2. X-ray, density, and optical data on the analysed mineral are given.
Synthesis of K2SiSi3O9 with silicon in 4- and 6-coordination
Authors: Kinomura N. , Kume S. , Koizumi M. 
Published: December 2006

SummaryTwo kinds of vitreous material with composition K2GeSi3O9 and K2Si4O9 were treated under conditions of high temperature and pressure. The X-ray diffraction patterns of the products were similar to that of K2TiSi3O9, which has the wadeite, K2ZrSi3O9, structure.A natural crystal of K-feldspar was also treated under the same conditions. The product was found to consist of three phases, coesite, kyanite, and the above-mentioned K2Si4O9. Since Zr ions in wadeite are in a 6-coordinated site, one-quarter of Si ions in K2Si4O9 are considered to be in 6-coordination. This is the first silicate in which Si ions occupy sites of 4- and 6-coordinations in one crystal at the same time.
Fluorine and chlorine in peralkaline liquids and the need for magma generation in an open system
Authors: Bailey D. K. , Macdonald R. 
Published: December 2006

SummaryFluorine, chlorine, zinc, niobium, zirconium, yttrium, and rubidium have been deter-mined on fifteen obsidians from Eburru volcano (Kenya Rift Valley), spanning the range from pantel-leritic trachyte to pantellerite. All pairs of elements show positive correlation coefficients, ranging between 0·769 and 0·998, but with most values better than 0·900. In spite of some very high correlations, only two of the twenty-one best-fit lines pass near the origin of the Cartesian coordinates. Linear distributions are found within two separate groups of elements: F, Zr, Rb; and Cl, Nb, Yt. Zn behaves in general as a member of the second group but seems to be subject to an additional variation. When an element from the fluorine group is plotted against one from the chlorine group the resulting pattern is non-linear. Therefore, although the elements in both groups would generally be considered ‘residual’ (partition coefficients between crystals and liquid approaching zero) there are clearly detectable differences in their variation, and hence their behaviour.Major-element variations in the obsidians are such that a vapour (fluid) phase would be needed to account for any magma evolution. The trace-element patterns are also impossible by closed-system crystal fractionation and suggest that this fluid may have been rich in halogens, with the metallic elements forming preferred ‘complexes’ with either F or Cl. The F-Zr-Rb ‘complex’ also varies quite independently of the important major oxides (e.g. A12O3) in the rocks. In the case of Rb this is but one aspect of a more significant anomaly, in which there is no sign of any influence of alkali feldspar (which partitions Rb) in the variation. This is remarkable because trachytes and rhyolites have normative ab+or > 50 %, and any evolutionary process controlled by crystal ⇋ liquid interactions must be dominated by the melting or crystallization of alkali feldspar. The results on the Eburru obsidians show that if they are an evolutionary series then either, the process was not crystal ⇋ liquid controlled, or that any such process has been overriden (or buffered) by other processes that have superimposed the observed trace-element patterns. In the latter event, the buffering phase may have been a halogen-bearing vapour.The same considerations must apply to other pantellerite provinces where Rb appears to have behaved as a ‘residual’ element.
Iraqite, a new rare-earth mineral of the ekanite group
Authors: Livingstone A. , Atkin D. , Hutchison D. , Al-Hermezi H. M. 
Published: December 2006

SummaryIraqite, a new mineral of the ekanite group from northern Iraq, has the composition (Ln1·33 Th0·66x0·15) (K1·07y0·93) (Ca3·49 Ln0·35 Na0·16) (Si15·69 Al0·27) (O39·93 F0·07) where x = U, Pb, Zr, Fe, Mg, and Cu, and y is presumed to be vacant sites. It occurs in granite in contact with dolomitic marble. The colour is pale greenish yellow; H 4½ Dcalc 3·28 and Dmeas 3·27 (Berman balance), both corrected for minor impurity and non-structural water. Optically it is uniaxially negative with ω 1·590 and ε 1·585 though some sections show anomalous extinction up to 7°. Space group is P4/mcc with a 7·61±0·01 and c 14·72±0·02 Å. Strongest lines of the indexed powder pattern are 5·28(100), 3·31(100), 2·64(100), 7·36(80), 3·38(80), 3·40(60), 2·7(40), 7·62(30). Thermal data are given.