bluuebunny/crossref_metadata_2025_split huggingface dataset:
A first attempt at a determination of felspars by activation analysis
Authors: Bradley J. E. S. , Bradley Olive 
Published: December 2006

SummarySmall crystals (2 mg.) of plagioclase and potassium felspar were irradiated for four weeks in an atomic pile. Subsequent analysis of the radiation showed that this is a possible method for the determination of the sodium and potassium content, and it should be possible to develop the method further in this direction. It has not proved a suitable method for the determination of calcium.
Sepiolite at a locality in the Keuper Marl of the Midlands
Authors: Keeling P. S. 
Published: December 2006

SummarySepiolite has been identified in the Keuper Marl at a Midlands locality by X-ray diffraction data, electron microscopy, differential thermal analysis, and chemical analysis. It has been calculated that a sample representing 30 ft. thickness of clay may contain as much as 39 % sepiolite. Apart from sepiolite, the Keuper Marl in the area examined consists mainly of mica, quartz, calcite, and ferric oxide.
A further investigation of tobermorite from Loch Eynort, Scotland
Authors: Gard J. A. , Taylor H. F. W. 
Published: December 2006

SummaryThe specimen described by Claringbull and Hey (1952) has been re-examined using electron-microscope, electron-diffraction, X-ray, and dehydration isobar methods. It differs from other specimens in several respects. The basal spacing does not shrink appreciably on dehydration. The principal cleavage is (100) and not (001). The body-centred pseudo-cell of normal dimensions, but the distribution of the weak reflections differs from that found for other specimens. The mechanism of conversion into wollastonite has also been examined.
Abraded pyrite crystals from the Witwatersrand gold mines
Authors: Frankel J. J. 
Published: December 2006

SummaryMetamorphosed dyke rocks in Witwatersrand gold mines carry pyrite crystals of unusual appearance. These crystals, particularly along the dyke margins, show curved and scratched surfaces that cut across crystal faces. The abrasion of the crystals is due to movement of dyke material under pressure. There is some suggestion of surface flow on the abraded surfaces. No deformation or granulation was obtained in laboratory experiments on pyrite crystals. Pressure shadows around the pyrite are described.
The photoelectric measurement of reflectivity
Authors: Bowie S. H. U. 
Published: December 2006

SummaryA simple photoelectric-cell attachment for use with an ordinary oremicroscope is described. Stabilization of the light source and accurate calibration of the photometer enable reflectivity values to be determined within an accuracy of 1% of the measured value. The choice of a universally acceptable standard is discussed. The photometer can be used with white light or with light of different wave-lengths. Bireflection, dispersion, and dispersion of the bireflection can readily be measured.
Rhodesite, a new mineral from the Bultfontein mine, Kimberley
Authors: Mountain E. D. 
Published: December 2006

SummaryA small specimen at first thought to be natrolite has proved to be a new mineral, for which the name rhodesite is proposed; it is fibrous, with α 1·502, β 1·506, γ 1·515, elongation γ, extinction straight, sp. gr. 2·36. The composition is near 4(Ca,Na2,K2)O. 10SiO2. 7H2O, and the water is all zeolitic.
Some zoned skarns from granite-marble contacts near Puyvalador, in the Quérigut area, eastern Pyrenees, and their petrogenesis (With Plate XIX.)
Authors: Watters W.A. 
Published: December 2006

SummaryDescriptions, with chemicaland mineralogical data, are given of zoned wollastonite-grossular-clinozoisite skarns found at the contact of limestone and granite at Puyvalador, near Quérigut, France. It is shown that the silica and alumina necessary for the formation of the skarn were supplied by the adjacent granite, which in return received lime from the marble replaced by the skarn zones. The modified facies of the granite in contact with the skarn is also described; it shows evidence of migration of silica towards the contact and of accumulation of lime derived from the neighbouring marble.Similar, but not identical, changes are found at other localities along the Quérigut granite contact with limestone. The features of the Puyvalador granite-limestone contacts are compared and contrasted with those described from some other regions. The contact rocks dealt with here are characterized by the presence of abundant clinozoisite, indicative of relatively low temperatures and abundance of water at the contact in the later stages of evolution of the granite.
Zeophyllite
Authors: Chalmers R.A. , Dent Lesley S. , Taylor H. F. W. 
Published: December 2006

SummaryA new analysis gives the formula Ca4Si3O12F2H6; the specimen was from Alter Berg, Leitmeritz, Bohemia, and also contained apophyllite. The unit cell is triclinic, but all reflections can be indexed on a geometrically monoclinic cell which is c-face centred and has a 16·2, b 9·34, c 13·2 Å., β 113°, Z = 6, principal cleavage (001). This cell could also be described as having a hexagonal base of side 9·34 Å., but with c tilted through 23° from the vertical in the plane of one of the sides. A dehydration curve showed a step at 300–400°C., corresponding to loss of two-thirds of the water. The remaining water is lost between 400° and 940° C., together with some fluorine, the latter probably as HF. Crystals heated at 450–600° C. retain the hexagonal-based cell, but d001 shrinks from 12·1 to 11·1 Å, and there is evidence of much stacking disorder of layers normal to c. Single crystals heated at 700° C. show ordered transformation, giving cuspidine twinned in three orientations as the only recognizable product. At 940°C. a mixture is obtained, mainly β-CaSiO3 with some β-Ca2SiO4.
The infra-red spectra of talc, saponite, and hectorite
Authors: Farmer V. C. 
Published: December 2006

SummaryThe absorption spectra of talc, saponite, and hectorite between 4000 and 400 cm. −1 are closely related, although the bands of the smectites are more diffuse as a result of isomorphous substitutions in the tale structure. Using oriented specimens, vibrations in which the change of dipole moment is perpendicular to the sheets of the minerals are identified, and the results compared with theoretical predictions. Three bands arising from the stretching vibrations of interlayer water molecules in the smectites are distinguished, one of which corresponds to a very weak hydrogen bond. Spectral changes arising from vigorous grinding are discussed.
Cornubite, a new mineral dimorphous with cornwallite
Authors: Claringbull G. F. , Hey M. H. , Davis R. J. 
Published: December 2006

SummaryA new copper arsenate, dimorphous with cornwallite, has been found on specimens from five localities in Cornwall, one in Devon, and one in Cumberland. The name cornubite (from Cornubia, the medieval Latin name for Cornwall) is proposed for the new mineral. Chemical analyses of cornubite and cornwallite agree well with Cu5(AsO4)2(OH)4; sp. gr. cornubite 4·64, cornwallite 4·52. X-ray study suggests that the unit-cell of cornubite has a volume of 228 Å.3 or a simple multiple thereof. New X-ray data for cornwallite (a 17·33, b 5·82, c 4·60 Å., β 92° 13′) agree well with L. G. Berry's except for a. Powder data for both are given.
The formation of a diffusion reaction skarn by pure thermal metamorphism (With Plates I and II.)
Authors: Kennedy W. Q. 
Published: December 2006

SummaryVeins and nodules of cornstone, enclosed in sandstone, have reacted to the thermal influence of a Tertiary dolerite dyke by the development of a wollastonite reaction skarn. This can be shown to have formed as a result of pseudomorphous replacement of the quartz grains by wollastonite, due to outward diffusion of calcium. The process is believed to have taken place at the inversion temperature of quartz (573° C.).
Residual hydroxyl groups in the metakaolin range
Authors: V. Stubičan  
Published: December 2006

SummaryInfra-red absorption spectroscopy has been used to study the retention of hydroxyl groups by kaolinite and halloysite after heat treatment in the range 600° C. to 850° C. Structurally disordered specimens initially lose water more rapidly than do ordered specimens, but retain hydroxyl groups at higher temperatures. Work on the phases obtained above 1100° C. is incomplete, but results for the lower temperatures indicate that the ordered structures tend to retain their atomic arrangement and form metakaolin, whereas disordered structures readily rearrange to yield γ-alumina, to the formation of which water is probably essential.
Order and disorder in the feldspars, I
Authors: Megaw Helen D. 
Published: December 2006

SummaryFeldspar structures are classified into small-cell (c ≈ 7 Å.) and largecell (c ≈ 14 Å.) types, as a preliminary to a discussion of the nature of substitution disorder, position disorder, and stacking disorder, and of the relations between them. Diffraction effects characteristic of the different types of disorder are considered and related to experimental observation as far as possible.
Delorenzite is tanteuxenite
Authors: Butler J. R. , Embrey P. G. 
Published: December 2006

SummarySpecimens of delorenzite from the type locality, Craveggia, Val Vigezzo, Piemont, have been examined and found to be close to tanteuxenite from Australia. The X-ray powder patterns are virtually the same, and the chemical analyses (including the relative abundances of the rare earths) are closely similar.Zambonini's original (1908) specimens have not been re-examined, but are without reasonable doubt the same as the specimens now described; the considerable discrepancies between the old and new analyses can be explained by the difficulty of the separations. It is suggested that the name delorenzite be abandoned despite its priority because of its association with an incorrect analysis.
A mineralogical application of X-ray absorption microspectroscopy: the hydration of larnite
Authors: Long J. V. P. , McConnell J. D. C. 
Published: December 2006

SummaryThe technique of X-ray absorption microspectroscopy is described, with particular reference to the determination of calcium in a hydrogel formed in minute amounts in cavities in larnite. The method, which is applicable to other elements, enables chemical data to be obtained from selected small areas in a normal petrological thin section.
An X-ray study of exsolution phenomena in the Skaergaard pyroxenes
Authors: Bown M. G. , Gay P. 
Published: December 2006

SummaryThe single crystal X-ray methods for the study of exsolution phenomena in pyroxenes previously described by the authors have been applied to the pyroxenes of the Skaergaard intrusion. The results for about fifty pyroxene crystals, selected from various levels between the chilled margin and a height of 2600 metres in the layered series, are presented and are correlated with previous optical descriptions. Whilst the correlation between the results of the optical and X-ray examinations is in general satisfactory, the present investigation shows that the X-ray techniques can in some cases extend our knowledge of the Skaergaard pyroxenes.
Chemical variations in members of the fergusonite-formanite series
Authors: Butler J. R. , Hall Rosemary 
Published: December 2006

SummaryAttention is drawn to anomalies in the nomenclature of the niobatetantalates, and the fergusonite series as used by Dana is renamed the fergusonite-formanite series. Chemical variations in this series are discussed with particular reference to H2O, Ca, Ti, Yt, individual lanthanons, Th, and U. Members of the series usually show heavy lanthanons exceeding light lanthanons but one specimen shows high Gd+Tb+Dy.
Two synthetic compounds containing chromium in different valency states
Authors: Johnson W. 
Published: December 2006

SummaryTwo compounds, one an apatite and the other a perovskite, have been synthesized by sintering mixtures containing CaO and Cr2O3, and CaO, Cr2O3, and Fe2O3 respectively. The apatite formed by partial oxidation of the Cr2O3 and subsequent pick-up of moisture from the atmosphere, to give Ca5(CrO4)3OH. The perov-skite formed as a non-stoicheiometric compound Ca4(Fe,Cr)4O11 by partial oxidation of the Cr2O3 during firing. Lattice parameters and interplanar spacings are given for the two structures.
Secondary minerals of the Tertiary basalts, Barrington, New South Wales
Authors: Nashar Beryl , Davies M. 
Published: December 2006

SummarySecondary minerals described from Tertiary amygdaloidal basalts in the Hunter Springs area, Barrington, New South Wales, are regarded as having been deposited from cold solutions some considerable time after consolidation of the basalts. The constituents in the solutions were evidently derived from the basalts by the action of circulating meteoric waters rather than by deuteric activity.
On a skarn monazite occurrence from the Namib desert near Usakos, South-West Africa
Authors: von Knorring O. , Clifford T. N. 
Published: December 2006

SummaryAn unusual monazite deposit of metasomatic origin is described. The monazite occurs as randomly oriented crystals in a dolomitic marble. The chemical composition and optical data of the monazite are given.
The use of Buerger's algorithm in crystallographic calculations
Authors: Davis R. J. 
Published: December 2006

SummaryBuerger (Zeits. Krist., 1957, vol. 109, p. 42) describes an algorithm for deriving data for the reduced unit cell from those obtained for an arbitrary crystal setting. It is shown that indices can be added to the algorithm so that one also derives the transformation matrix for the change of setting. Conversely, a known transformation matrix forms a set of instructions for using the algorithm to transform unit cell data, whether X-ray or morphological, from the initial to the final setting, One can thus use the algorithm to calculate the lengths of any unit cell vectors and the angles between them, and, using reciprocal cell data, to obtain any interfacial angles. Worked examples of these applications show that the proposed calculation method is shorter and simpler than those at present accepted.
Some new platinoid-rich minerals, identified with the electron microanalyser (Plate XVII)
Authors: Stumpfl E. F. 
Published: December 2006

SummaryMinerals approximating to the formulae PtSb2, PtSb, Pt(Sb,Bi), (Pt,Ir)As2, Pt(Ir,Os)2As4, Pd2CuSb, Pd(Sb,Bi), Pd8CuSb3, Pt4Sn3Cu4, and (Fe,Ni)2S have been discovered as fine intergrowths in platinum concentrates from the Driekop mine, Transvaal, South Africa. Conventional ore microscopy also proved the presence of most of the known minerals of the platinum paragenesis. The namegeversiteis proposed for the phase PtSb2.
Chlorites from granitic rocks of the central Sierra Nevada batholith, California
Authors: Dodge F. C. W. 
Published: December 2006

SummaryOccurrence and major- and minor-element compositions of chlorites from plutonic rocks of the central Sierra Nevada batholith have been studied in detail.Chlorite has formed largely as an alteration product of biotite, presumably late in the magmatie history of the granitic rocks as a result of subsolidus reaction. Major-element composition of chlorite is strongly influenced by composition of coexisting biotite. Minor-element differences between the two minerals can, for the most part, be attributed to structural differences. The minor-element data, particularly for Cu, indicate that the process of chloritization is not a likely mechanism for release of ore metals from primary minerals.
Heyite and brackebuschite compared
Authors: Symes R. F. , Williams S. A. 
Published: December 2006

SummaryHeyite (see preceding paper) is so strikingly similar to brackebuschite that a close comparison of the two species seemed advisable. Topotype brackebuschite (B.M. 55819) was used for this purpose.Brackebuschite is a vanadate of lead, manganese, and iron, heyite a vanadate of lead and iron. Both species are monoclinic with diffraction symmetry P21 or P21/m. The X-ray cells are remarkably close: a = 8·810, 8·910; b = 6·155, 6·017; c = 7·651, 7·734; β = 111° 30′, 111° 53′ (brackebuschite first). As might be expected, powder patterns are strikingly close as well.Other than the similarities noted above, the minerals differ so fundamentally that they cannot be the same—they are valid and distinct species. Optic orientations show α: [001] 20° (in acute β) for brackebuschite, 36° (in obtuse β) for heyite. Indices are (brackebuschite first): α 2·28, 2·185; β 2·38, 2·219; γ 2·49, 2·266 for the sodium D line.Chemical differences are irreconcilable and reaffirm brackebuschite as Pb2(Mn,Fe,Zn)(VO4)2.H2O while heyite is Pb5Fe2(VO4)2O4.
Elastic anisotropy in minerals
Authors: Newnham R. E. , Sub Yoon Hyo 
Published: December 2006

SummarySilicate minerals show several correlations between structure type and elastic constants. Stiffness coefficients are generally larger in the direction of Si-O bonding. A simple mechanical analogy in which atomic bonds are simulated by springs connected in series and parallel is used to estimate the size and anisotropy of the elastic moduli and their pressure derivatives.
On an anatectic granite from Bygland, south Norway
Authors: Sen R. , Deb Mukherjee Ananda 
Published: December 2006

SummaryThe Pre-Cambrian granitic rocks of Bygland are structurally and texturally concordant with the metamorphosed country rocks. Both these rock types plot close together in Q-Or-Ab and Ab-An-Or normative diagrams; trace element distribution is also similar. The granite has been reconstituted from the country rocks under epidote-amphibolite facies conditions. Plagioclase feldspars show that the granite is not a ‘mature’ rock; they are, however, ‘mature’ in the country rocks and are products of typical regional metamorphism (Ohta et al, 1968). Plagioclases in the granite are relicts of country rocks showing traces of a premetamorphic crystalline state. They have been rejuvenated with the introduction of alkali material during the reconstitution.
Quetzalcoatlite, Cu4Zn8(TeO3)3(OH)18, a New Mineral from Moctezuma, Sonora
Authors: Williams Sidney A. 
Published: December 2006

SummaryQuetzalcoatlite is a new mineral from the Bambollita mine in the Sierra La Huerta near Moctezuma, Sonora, Mexico. The colour is Capri blue (R.H.S. 120A) with a pale streak. H = 3; G meas. = 6·05±0·3 G calc. = 6·12. Crystals up to 0·4 mm long were not measurable but are acicular to prismatic, hexagonal, with fair cleavage on {100} 10·097 Å, c 4·944, space group C632. Z = I. Strongest lines are 8·752 (100), 2·748 (70), 2·520 (42B), 3·531 (40), 3·273 (31), 1·766 (28), 5·054 (21), 2·250 (20). Electron probe analysis gives: CuO 20·3%, 18·9, 20·9; ZnO 41·2, 38·2, 38·7; TeO2 29·4, 31·3, 30·6. Water by Penfield method on 2.265 mg gave 10·1%. Empirical cell contents are Cu4·01Zn7·73Te3·04O8·88(OH)17·89 or Cu4Zn8(TeO3)3OH18. Pleochroic with ε = colourless, ω = pale blue-green; uniaxial (-) with εD = 1·740, ωD = 1·802. Named for the Toltec god Quetzalcoatl.
Chrome-spinels from the Massif du Sud, southern New Caledonia
Authors: Rodgers K. A. 
Published: December 2006

SummaryApproximately forty, variously shaped, chromitite bodies occur in dunites and harzburgites of the alpine-type peridotite complex of southern New Caledonia. The chromitites consist of pichrochromite (59 to 42% Cr2O3) and serpentinized olivine (Fo96-92) and display a variety of textures (massive, disseminated, and orbicular) consistent with a magmatic cumulate origin. Dunites contain olivine (Fo93−97) and 1 to 3% picrochromite (50 to 39% Cr2O3). Harzburgites have less than 1% spinel, ranging from picrochromite to ceylonite (45 to 28% Cr2O3) and often forming symplectic intergrowths with bronzite. Temperatures of crystallization of the cumulate picrochromites are believed to have been about 1200 °C while the more aluminous symplectic spinels equilibrated under different conditions and may reflect a late stage recrystallization episode.
Synthesis of potassium manganese oxides under hydrothermal conditions
Authors: Endo T. , Kume S. , Shimada M. , Koizumi M. 
Published: December 2006

SummaryA 1 M solution of potassium permanganate was sealed in a gold capsule and was treated under conditions of temperature and pressure up to 800 °C and 2·5 kb. Different kinds of products were produced under different conditions of synthesis, and potassium manganate, birnessite, cryptomelane, hausmannite, manganosite, and a new phase appeared. The chemical composition of the new phase was determined as K2Mn4O9 and its X-ray powder diffraction pattern was indexed on a hexagonal cell with a 11·295 and c 21·870 Å.
Oxygen partial pressures; control, variation, and measurement in quench furnaces at one atmosphere total pressure
Authors: Biggar Gordon M. 
Published: December 2006

SummaryOxygen partial pressures in atmospheric-pressure quench furnaces were found to vary by as much as 0·5 in log fo2 when changes were made in gas flow rate and direction suggesting that careful analysis of the gas mixture supplied to a furnace is not a guarantee of the oxygen pressure that a sample in the furnace will attain. The use of magnesiowüstite compositions, with variable oxygen contents, as indicators of oxygen pressure is described.
Bitburg—a group-IB iron meteorite with silicate inclusions
Authors: Rambaldi E. , Jagoutz E. , Wasson J. T. 
Published: December 2006

SummaryChemical and mineralogical investigations show that the Bitburg meteorite is not a pallasite, but a group-IB iron meteorite. Like other members of this group it contains chondritic silicates.
Cesbronite, a new copper tellurite from Moctezuma, Sonora
Authors: Williams Sidney A. 
Published: December 2006

SummaryCesbronite occurs at the Bambollita mine, near Moctezuma, Sonora, with a variety of other tellurites. The colour is ‘green beetle’ (R.H.S. 135-B) with a pale streak. H 3; Dmeas 4·45±0·2. Crystals are orthorhombic 2 mmm with a 8·624 Å, b 11·878, c 5·872 (all ± 0·016 Å); space group Pbcn. For Z = 2 the calculated density is 4·455 g/cm3. The strongest powder lines are 5·934 (100), 3·490 (92), 4·889 (71), 2·358 (70), 2·379 (38), 1·592 (34), 2·156 (28), and 1·698 (27). Electron-probe analysis gave: CuO 50·3 %, 50·3, 49·8, 49·4; TeO2 39·3 %, 39·2, 38·6, 38·6. Water determined gravimetrically 11·0 %. This gives Cu5(TeO3)2(OH)6.2H2O.Cesbronite is pleochroic with absorption γ ≈ β ≫ α. Optically positive with 2Vγ calc. 72°; α 1·880 ‖[100], β 1·928 ‖[001], γ 2·029 ‖[010].
Crystallization history of a zoned plagioclase
Authors: Pringle G. J. , Trembath L. T. , Pajari G. E. 
Published: December 2006

SummaryElectron microprobe and textural data are used to deduce a crystallization history for plagioclase in the Grand Manan Island (Canada) diabase sheet. The plagioclase crystals consist of a prominent core (An79-67) surrounded by a distinctly more calcic zone (An82-76), which grades into a normally zoned mantle (An73-40). This zoning pattern is interpreted as reflecting the elevation of a dry diabase magma from at least 10 to 20 km to near surface conditions.