bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dichroscopes for microscope stage and ocular
Authors: Dollar A. T. J. 
Published: December 2006

The optical accessories here described are two dichroscopes to facilitate microscopical comparisons by eye between the hues and intensities of axial absorption colours shown by thin slices, crushed fragments, or detrital grains of transparent coloured doubly-refracting crystals. Their chief applications lie in microscopic mineralogy and petrology, but they can be of service, also, in chemistry and allied subjects.The aims of the accessories are two in number. They provide: (i) simple microscopic means for viewing simultaneously any pair of distinct hues, intensities of hue, or combinations of these variables, which result from differential absorption of white light; and (ii) a convenient method for detecting small differences between any pair of hues, intensities, or both, in terms of immediate ocular comparison between two sets of small symmetrically-shaped coloured images which alternate, and meet in straight boundaries.
Angular relations between equivalent planes and distances between equivalent points in symmetrical point groups
Authors: Niggli Paul 
Published: December 2006

A fundamental problem arising out of the study of symmetrical point groups can be formulated as follows: Let N points in threedimensional space be connected two and two in every possible way by straight lines: what relations must exist between the lengths of these lines if the points are equivalent members of a symmetrical point group ?The methods of projection used in crystallography (e.g. the stereographic projection) at once show that the points may be considered to be the images of straight lines or planes. The problem formulated above has therefore a direct application to descriptive crystallography and can in this connexion be stated as follows:A complex of N planes is determined by the points of intersection of the normals with the surface of a unit sphere, i.e. by their poles. What now must the angular relations between the planes be if all are equivalent, that is to say, belong to one and the same simple form ?
The graphitization of diamond and the nature of cliftonite. (With Plate XXVI)
Authors: Grenville-Wells H. J. 
Published: December 2006

SummaryIt has long been known that if a diamond is heated in pure oxygen, or even in air, to a temperature of about 700° C. or higher (depending on the initial quality of the diamond), it will be wholly or partially oxidized to CO or CO2, but that if the diamond is heated in the absence of oxygen—preferably in vacuo—to a temperature of about 1500° C. or higher (again depending on the initial quality of the diamond), it will be wholly or partially converted to graphite. For complete conversion the graphite is always poly crystalline. The partial conversion of diamond to graphite is, however, of considerable interest, because when graphite forms on a single crystal of diamond it exhibits a strong preferred orientation.
The unit cell and space-group of alamosite (PbSiO3)
Authors: Mackay A. L. 
Published: December 2006

Alamosite was first described by Palachc and Merwin, i who thought it might be isomorphous with wollastolfite. For that reason it has been re-examined, using X-ray methods.A specimen from the original locality at Alamos, Sonora, Mexico (B.M. 1910,330) was made available through the courtesy of the British Museum (Natural History), and in physical appearance it tallied with the original description. The crystals were aggregates of fibres arranged in bundles which cleaved perfectly perpendicular to the fibre axes. Small tablets could be readily cut out for X-ray analysis. The refractive indices were very high and the dispersion was large. As the axial ratios found by X-ray methods agreed with those given by Palache and Merwin, the latter's chemical analysis and density determination were not repeated.
Okenite and nekoite (a new mineral) (With Plate I.)
Authors: Gard J. A. , Taylor H. F. W. 
Published: December 2006

SummaryThe unit cell of okenite (CaO.2SiO2.2H2O) has been determined for a specimen from Bombay, India, using a combination of X-ray, electron-microscope, and electron-diffraction methods. It is anorthic with a 9·84, b 7·20, c 21·33Å., α 90·0°, β 103·9°, γ, 111·5°, elongation b, Z 9. These data are compatible with the goniometric results of Boggild (1922) and allow the latter to be interpreted.A specimen from Crestmore, California, which Eakle (1917) had described as okenite, was also examined. It was found to be a new species, having the same composition as okenite but distinguishable from it by its optical properties, X-ray powder data, and unit cell. The latter is anorthic with a 7·60, b 7·32, c 9·86 Å, α 111° 48′, β 86° 12′, γ 103° 54′, elongation b, Z = 3. Because of the relation to okenite, the name nekoite is suggested.
On the correlation of physical properties with chemical composition in multivariate systems
Authors: Hey Max H. 
Published: December 2006

SummaryA systematic and time-saving procedure for the correlation of optical or other physical properties with chemical composition is outlined, and is applicable even where the composition is complex and involves several variables. The procedure is applied to anthophyllite, for which the following partial regression equations are derived:γ = 1·7249−0·0130Si+0·0140(Ti+Fe‴+Fe′+Mn)±0·0012,β = 1·7275−0·0142Si+0·024(Ti+Fe‴)+0·0110(Fe″+Mn)±0·0015,α = 1·6951−0·0117Si+0·040(Ti+Fe‴)+0·0133(Fe″+Mn)±0·0025,b(Å.) = 16·44+0·28Si−0·13Mg+0·40(Ca+Na+K)±0·04.The a and c cell-dimensions appear to be constant, within the experimental error of the available data.
Replacements involving early carnallite in the potassium-bearing evaporites of Yorkshire
Authors: Stewart F. H. 
Published: December 2006

SummaryEvidence from four recent boreholes in the Yorkshire potash field suggests that carnallitic was an important original constituent of the Middle Evaporite Bed, and that much of the sylvine of the potash zone is of secondary origin.The carnallitie rocks have been affected by complex replacements, an earlier series involving sylvine, halite, and anhydrite, and a later series involving rinneite, halite, sylvine, and carnallitic.
Staurolite twinning (With Plates V-VI.)
Authors: Hurst Vernon J. , Donnay J. D. H. , Donnay Gabrielle 
Published: December 2006

SummaryThe space group Ccmm of the accepted staurolite structure (7·82:16·52:5·63 kX 0·473:1:0·341, Náray-Szabó 1929) is a pseudo-space group; the true one has no c glide plane. Staurolite is monoclinie pseudo-orthorhombic, as shown optically by horizontal dispersion and morphologically by unequal developments of forms r(201) and r′(01). It has variable cell dimensions, 7·83–7·95:16·50–16·82:5·62 5·71 Å., constant β 90° + 3′, aspect C*, and probable space group C2/m (negative pyroelectric test). This leads to the prediction of a new type of twin, ‘by high order merohedry’, a penetration twin that simulates an orthorhombic single crystal. It is known (Friedel, 1922) that the 90°-cross can be accounted for by two different twin laws and the 60°-cross by five. The twin operations are respectively the pseudo-symmetry operations of a pseudo-tetragonal cell, obtained by transformation 010/003/100, and those of Mallard's pseudo-cube, resulting from transformation 013/03/300. By precession methods more than one twin law is established for each type of cross: both laws [100]90° and [013]180° are found for 90°-crosses: [313]180 and [102]120°, for 60°-crosses.
Experimental and theoretical studies of the mica polymorphs
Authors: Smith J. V. , Yoder H. S. 
Published: December 2006

SummaryAn experimental and theoretical study has been made in order to determine the number and the structure of the possible polymorphs and to determine the structural relations between them. The simplest structures are 1M, 2M1, 2M2, 3T, 20, and 6H polymorphs, and more complicated types can be developed. Some of the previously described polymorphs were not contained in the theoretical list and were re-examined. The 6M structure was found to be a 2M2polymorph, the 6-layer triclinic type was found to be a 2M1polymorph, and the 3M structure was shown to be a 3T type. The 24-layer triclinic structure could be described on a simpler 8-layer cell. This type together with a new 12-layer monoclinic structure, as well as other structures of higher periodicity, presumably consists of complex stacking and results from spiral-growth mechanism. Two extreme types of layer-disordered crystals may be built and a disorder of individual ions may also occur. Single stacking faults result in twinned crystals. A new twin relation (180° rotation about the [100] axis) has been recognized. Twenty specimens from extreme geological environments have been examined in order to evaluate the control of environment on the stacking. The type of stacking could not be attributed solely to the influence of pressure and temperature. Composition appears to play a dominant role in the type of stacking, and semi-quantitative structural arguments appear to support this contention. The influence of growth mechanism is discussed. A scheme for the identification of the mica polymorphs by X-ray powder and single-crystal methods is given.
A case of epitaxic replacement
Authors: Kostov Ivan 
Published: December 2006

SummaryQuartz from a granite pegmatite near Kalkovo, Bulgaria, has undergone partial replacement by biotite along cracks parallel to (01;0); the biotite is in regular orientation relative to the quartz, and appears to constitute an instance of epitaxic replacement, defined as a replacement in which the replacing mineral develops in a regular, structurally controlled orientation relative to the mineral replaced.
Kingite, a new hydrated aluminium phosphate mineral from Robertstown, South Australia
Authors: Norrish K. , Rogers Lillian E. R. , Shapter R. E. 
Published: December 2006

SummaryA new hydrated aluminium phosphate mineral,kingite, from phosphate workings near Robertstown, South Australia, has an idealized formula Al2O3.Al(OH)3.P2O5.9H2O, with some replacement of OH by F. The specific gravity is 2·2 to 2·3, refractive index 1·514, and percentage chemical composition Al2O331·92, P2O528·63, H2O 37·93. The three strongest lines on the X-ray diffraction pattern are 9·1, 3·45, and 3·48 Å. Kingite changes to a less hydrated phase between 154° C. and 163° C., which is also considered to be a new aluminium phosphate (meta-kingite) with idealized formula Al2O3.Al(OH)3.P2O5.4H2O. The strongest lines of its X-ray diffraction pattern are at 7·4, 5·02, and 37·19 Å.
Measurement and distribution of zircons in some granitic rocks of magmatic origin
Authors: Larsen Leonard H. , Poldervaart Arie 
Published: December 2006

SummaryMorphological characters of zircons in concentrates have been studied by measurement of length along the c-axis and breadth along the a1- or a2-axis of 200 doubly terminated crystals for each sample. The sample is represented graphically by a line fitted mathematically to a scatter plot of the measurements. This line, the reduced major axis, is visualized as a growth trend, and samples are described and compared statistically.From a careful study of zircons in a tonalite it is concluded that zircon crystallized over a short range before crystallization of the main constituent minerals.The distribution of zircon in a batholith of magmatic origin has also been studied. The batholith grades from a core of granodiorite to a mantle of tonalite, but the zircons are uniform throughout. Small bodies of granodiorite and quartz monzonite have sharp contacts against the main batholithic rocks, and zircon samples from these intrusives differ from one another and from those of the batholith. It is concluded that the batholith represents a single intrusion which differentiated after emplacement, and that the later intrusives each crystallized under different conditions.
Rare earths in some niobate-tantalates
Authors: Butler J. R. 
Published: December 2006

SummaryRare-earth distribution has been determined for fourteen niobatetantalates containing essential rare earths. Those minerals with more than about 15 % TiO2 (and corresponding to either priorites or members of the euxenite-polycrase series) have Yt as the dominant rare earth with the heavier lanthanons in excess of the lighter lanthanons. Those minerals with less than about 4 % TiO2 and less than about 30 % (Yt,Ln)2O3 (and corresponding to samarskites) also have Yt as the dominant rare earth but they show a marked concentration of Gd + Tb + Dy over the other lanthanons. It is tentatively suggested that this power of selective lanthanon enrichment may be characteristic of samarskite among the niobate-tantalates examined.
Heat treatment of metamict euxenites, polymignites, yttrotantalites, samarskites, pyrochlores, and allanites
Authors: Lima-de-Faria J. 
Published: December 2006

SummaryThe standard thermal treatments proposed by Lima-de-Faria have been applied to metamict euxenites, polymignites, yttrotantalites, samarskites, pyrochlores, and allanites. In the case of these metamict niobotantalates a facecentred cubic phase is formed at 700° C., and at 1000°C. a more characteristic phase appears combined with the cubic one. In the case of allanites only a slight formation or strengthening of the original structure of allanite appears at 700°C., and at 1000°C. a cubic phase is formed together with other phases.
A hydrated barium-strontium pyrochlore in a biotite rock from Panda Hill, Tanganyika
Authors: Jäger E. , Niggli E. , Van der Veen A. H. 
Published: December 2006

SummaryA hydrated barium-strontium pyrochlore with only subordinate amounts of Ca and Na has been found in a weathered biotite rock (contact-rock of a carbonatite) from Panda Hill, Tanganyika, as small euhedral yellowish-grey cubic crystals (showing the combination of the octahedron and the cube) in a rock containing euhedral biotite, some orthoclase, and several other minerals. Hydrated Ba-Sr pyrochlore is isotropic, the refractive index varies from 2·07 to 2·10. The reflectivity (vertical illumination) is 13·2 %. H. Poor {111} cleavage. The pyrochlore structure (space-group O7h–Fd3m) and the unit-cell dimensions (a 10·562 Å.) are derived from X-ray powder and Weissenberg photographs. The calculated specific gravity is 4·01 (observed, 4·00 on dried material). Chemical analysis gives BaO 12·5, SrO 6·4, Na2O 0·28, K2O 0·25, CaO 1·35, rare earths (mainly Ce2O3) 2, ThO2 0·6, FeO 0·45, TiO2 3·9, Nb2O5 67·0, Ta2O5 0·22, H2O+ 4·0, other constituents 2·21, total 101·16. After deduction for impurities the following formula resulted: (Ba0·30Sr0·22Ca0·05Ce0·04Na0·03Fe0·02K0·01Th0·01)(Nb1·83Ta0·004Ti0·17)O5·61(H2O)0·80.The ideal formula for pyrochlore is A2B2O6(F,OH). In the mineral described only a third of the A-positions are occupied by Ba, Sr, etc. Infra-red spectrophotometry does not indicate hydroxyl-groups. When the mineral is treated with TINO3 solution the intensities of the X-ray diffraction lines 333/511, and 444 are changed; hydrated Ba-Sr pyrochlore shows a certain exchange-capacity.The name pandaite, from Panda Hill, is proposed for the new mineral.
A new method for thermal dehydration studies of clay minerals
Authors: Kulbicki Georges , Grim Ralph E. 
Published: December 2006

SummaryThe water vapour released upon heating the specimen is driven through a water absorber. The intensity of the exothermic reaction produced by absorption of the water is recorded against the temperature of the specimen. A series of curves obtained with various clay minerals are presented to illustrate the method. The significance of results in the identification of the clay minerals and the determination of their structure is considered.
The ageing of sesquioxide gels. I. Iron oxide gels
Authors: Mackenzie Robert C. , Meldau Robert 
Published: December 2006

SummaryThe gels prepared by adding ammonium hydroxide rapidly to ferric chloride solutions to various pH values are shown to consist of amorphous material and crystalline goethite ; no other iron oxide was definitely identified in the present experiments, although this does not preclude other oxides being present in gels prepared under slightly different conditions. The goethite grows as acieular crystals on ageing at all pH values, but the rate of growth is greater at higher pit values. The exothermic peaks appearing on differential thermograms of such gels are apparently due to coalescence of extremely minute hematite particles to give larger particles, the sharpness of the peak indicating to some extent the size of the original hematite particles. These observations are related to data for other iron oxides, and the morphology of ferric oxide polymorphs under the electron microscope is considered.
Electron-optical data for crystals of scarbroite
Authors: Brindley G. W. , Comer J. J. 
Published: December 2006

SummaryElectron micrographs of scarbroite show thin platy crystals of about 1 μ size, having rhombic outlines with angles 66° ± 1° and 113° ± 1°. Single-crystal electron-diffraction patterns show rectangular net patterns, with d100 = 9·90 Å., d010 = 14·67 Å., γ* = 90° ± 0·05°. Strong hk0 reflections show a pseudohexagonal arrangement, but true symmetry is probably orthorhombic or monoclinic. Faces outlining rhombic forms are of type {11l}, .
A possible explanation of immiscibility in silicate melts
Authors: de Wys E. Christiaan 
Published: December 2006

SummaryThe problem of silicate immiscibility, of petrological and technological interest, is discussed in terms of the structures of silicate crystals and certain phase diagrams. Physical chemical principles are employed to indicate the author's basis for suspecting that certain structures in the crystalline solid are carried over into the melt and are a major contributory cause of silicate immiscibility. These structures appear to be limited to the neso (SiO4)4−, soro (Si2O7)6−, cyclo (Si3O9)6−, and ino (SiO3)2− types of silicate polymers and do not include the more complex phyllo- and tecto-silicate polymers.
β-Ferric Oxyhydroxide
Authors: Mackay A. L. 
Published: December 2006

SummaryThe crystallographic properties of the hydrated iron oxide obtained by the hydrolysis of FeCl3 are described. The characterizing X-ray powder pattern can be indexed on a tetragonal unit cell with a 10·48 and c 3·023 Å. This cell is shown to contain eight formula units of FeOOH but Cl- or other anions are necessary for the crystallization of the material The structure is that of hollandite or α-MnO2. The unit cell has been confirmed by electron diffraction from single crystals having dimensions about 5000 × 500 × 500 Å. and twinning, which produces hexagonal stars, has been studied. On heating, the structure breaks down and recrystallizes as α-Fe2O2, probably with an intermediate stage involving a spinel phase.
A thermal study of thaumasite
Authors: Font-Altaba M. 
Published: December 2006

SummaryA differential thermal analysis curve of thaumasite shows an endothermal peak at 206° C., correspinding to the loss of H2O and CO2, and a weak exothermal peak at 709° C., corresponding to recrystallization to a mixture of anhydrite and larnite, as is shown by X-ray powder photographs of material heated to 950° C. Improved powder data for thaumasite are given: the three strongest lines are at 9·66, 3·79, and 4·58 Å., and the cell-dimensions are a 10·992, c 10·311 Å.
Magnetic susceptibility of garnet
Authors: Frost M. J. 
Published: December 2006

SummaryThe mass suseeptibility of 23 analysed or partially analysed garnets has been measured by means of a calibrated Franz Isodynamic magnetic separator. Straight lines are fitted to the adjusted data for mass susceptibility and molecular composition. The mass susceptibilities of the theoretical end-members in electromagnetic units × 106 are estimated as: almandine, 68±2 e.m.u.; spessartine, 81±3 e.m.u.; and andradite, 49±3 e.m.u. Grossular and pyrope are assumed to have susceptibilities of nil.
The cummingtonite problem
Authors: Layton W. , Phillips R. 
Published: December 2006

SummaryAn examination of available chemical analyses shows that the anthophyllite and cummingtonite series of amphibole minerals are not isodimorphous. Whilst the anthophyllites are truly lime-free amphiboles, small amounts of calcium are essential to stabilize the monoclinic lattice of cummingtonites, which should be regarded as lime-poor amphiboles, analogous to the lime-poor pyroxenes. The existence of synthetic clino-anthophyllites is considered.
A galena-wulfenite-uraniferous-asphaltite horizon in the Magnesian Limestone of Nottinghamshire
Authors: Deans T. 
Published: December 2006

SummaryThe top 2 inches of the Lower Magnesian Limestone is feebly but persistently mineralized along its outcrop from Nottingham to Doncaster, predominantly with galena and a little cerussite, frequently with uraniferous asphaltite containing 0·2 to 1% U3O8. Wulfenite, both platy and pyramidal in habit, occurs at Bulwell and Kirkby in Ashfield. The mode of formation and the age of these minerals are discussed.
Djurleïte from Calabona, Sardinia
Authors: Bernardini G. P. , Corsini F. , Tanelli G. 
Published: December 2006

SummaryDjurleïte has been identified by X-ray analysis in a sample from Calabona, Sardinia. Morphological characteristics, chemical composition, and thermal behaviour (studied by high temperature X-ray analysis and D.T.A.) are reported. Chemical composition and breakdown products upon heating differ from those of synthetic djurleïte in the Cu-S system.
Chemical variation in minerals of the astrophyllite group
Authors: Macdonald R. , Saunders M. J. 
Published: December 2006

SummaryEight new and fourteen published analyses of astrophyllites are used to examine chemical variation within the group. Al, Ca, Cs, F, Mg, Mn, Nb, Rb, Sn, Zn, and Zr may all substitute in moderate to large amounts in the unit cell, whose basic formula is (K,Na)3Fe7Ti2Si8(O,OH)31; the natural Mn- and Nb- analogues of astrophyllite have been recorded. Ba, Cl, Cu, Li, P, Pb, Sr, and Ta are present, but in smaller amounts. The majority of specimens show appreciable cation deficiencies, up to 5 % of sites remaining vacant. Astrophyllites from undersaturated igneous rocks are characterized by higher Al, Ca, Mg, Mn, (OH+F), (K+Na) and Zr, and lower Li, Pb, and Zn contents than those from oversaturated igneous rocks. A ‘high-alkali’ type of astrophyllite is distinguished. A new occurrence of nigerite is noted.
Low-iron cordierite in phlogopite schist from White Well, Western Australia
Authors: Pryce M. W. 
Published: December 2006

SummaryPale-blue cordierite (complete analysis given; shows total iron oxides only 0·98 %) occurs in phlogopite schist near White Well (24° 28′ 30″ S. 116° 2′ E.) 20 miles north-west of Yinnietharra, Western Australia. Associated minerals are corundum, dravite, and sillimanite, accessory zircon and rutile. The cordierite is in translucent masses to 8 ×8×4 cm with vitreous lustre, D 2·57, α 1.536, β 1·540, γ 1·543, all colourless, 2Vα80° Unit cell a 17·055, b 9·724, c 9·350 Å. The host phlogopite (complete analysis given) is in brown flakes to 1 cm, D 2·88, α 1·558, β 1·585, γ 1·59, 2Vα 5–20° 1 M polymorph.
Chemical weathering on the Carnmenellis
granite
Authors: Rice C. M. 
Published: December 2006

Summary
The behaviour of 25 major and trace
elements, together with mineral changes, has been
examined in a deep weathering profile on the
Carnmenellis granite, Cornwall. The bulk chemical
and mineralogical composition of the regolith
shows only minor changes from the parent rock
indicating a low degree of chemical weathering.
However, within the regolith marked differences
occur between the fine fractions from the various
horizons. Chlorite and degraded muscovite
characterize the fines of horizons
A+B
and C whereas gibbsite
and kaolinite characterize horizon
D. Secondary minerals
becoming base deficient with depth is the reverse
of normal behaviour and two possible theories are
advanced to explain this anomaly. Most of the
trace elements are concentrated in the < 10 µm
fraction of the various horizons, in part by an
association with degraded muscovite. Tin and Zr
occur in resistates and Be, Sr, and Co are mainly
lost during weathering.