bluuebunny/crossref_metadata_2025_split huggingface dataset:
Clay mineral transformations in podzolized tills in central Finland
Authors: Righi D. , Räisänen M. L. , Gillot F. 
Published: December 2006

AbstractTransformations of clay minerals were studied in a sequence of podzols (Entic Cryorthods) of increasing age (5500-10000 years BP) developed from till materials in central Finland. The age of the soils was estimated according to altitude above the present sea level, with reference to the age of ancient shorelines and the rate of land uplift. Clay minerals in fine (<0.1 µm), coarse (0.1-2 µm) clay and fine silt (2-5 µm) fractions were studied by X-ray diffraction. The layer charge of expandable minerals was estimated on the basis of their re-expansion with ethylene glycol following K-saturation and heating to 110°C Pedogenic transformations of clay minerals occur essentially in the E horizons of the podzols. Smectites and illite-smectite mixed-layers are the dominant clay minerals in the E horizons of soils older than 6500 years. The number of mixed-layers decreases with evolution of the soil, leaving a nearly pure smectite phase in the oldest soil (10000 years). The smectites are dioctahedral with a tetrahedral charge. Groups of low-charge and highcharge interlayers are both present in the samples, but low-charge smectite layers were found only in the two older soils (9500-10000 years). This suggests alteration with time of the high-charge smectites.
On the remarkable similarity in chemical and mineral composition of chondritic meteoric stones
Authors: Prior G. T. 
Published: December 2006

The observation of the striking similarity both in chemical and mineral composition of the Baroti, Wittekrantz, and St. Michel meteorites (see the preceding paper) suggested the idea of testing how far such a close relationship applied to other cbondritic meteoric stones.The practical identity in chemical composition of different meteoric stones has been often pointed out. For example, A. E. Nordenskiöld showed in the case of the stones of Erxleben, Lixna, Blansko, Ohaba, Pillistfer, Dundrum, Hessle, Orvinio, and Stäilldalen that the percentage chemical compositions differed very slightly if the proportions of the metals, silicon, &c., were considered instead of the oxides.
Chlorophaeite in the dolerites (tholeiites) of Dalmahoy and Kaimes Hills, Edinburgh
Authors: Campbell Robert , Lunn James W. 
Published: December 2006

The name chlorophaeite was given by John Macceulloch in 1819 to a mineral exhibiting striking colour change on exposure which he found at Craig nan Stàrdean (=Sgùrr Mòr) in the island of Rum. Sixty years later Professor Heddle visited the type locality and redescribed the mineral, giving for the first time chemical analyses. He also noted an occurrence of the mineral in Canna. In 1908 A. Harker showed that the rock which contained the chlorophaeite belongs to the mugearites.Records of chlorophaeite arc not always trustworthy since the term has been used somewhat loosely. Professor Heddle (loc. cit., p. 88) confirmed the occurrence at the Giant's Causeway, Co. Antrim, first recorded by Greg and Lettsom in their Manual of Mineralogy.
The structure of baddeleyite and of prepared zirconia
Authors: Yardley Kathleen 
Published: December 2006

The crystal used in the first part of this investigation, an untwinned specimen from Ceylon in the British Museum collection, was measured goniometrically and described in detail by Dr. G. F. Herbert Smith, who gave as its crystallographic constants :Density (p) 5.82 (grs./c.c.). Monoelinic prismatic,a:b:c = 0.9905 : 1:0.5110, β = 80° 32'.Owing to the comparatively largc size of the crystal and its high absorptive power it was unsuited either to the 'rotating crystal' or Laue photographic methods of X-ray examination, Reflections from the faces were observed on the Bragg ionization spectrometer and spacings measured with an accuracy of about 2 per cent.
Corundum twins from Transvaal
Authors: Spencer L. J. 
Published: December 2006

Lamellar twinning is of frequent occurrence in corundum, as evidenced by rulings on the surfaces and by the well-marked pseudo-cleavages (or partings) parallel to the faces of the primary rhombohedron and also parallel to the basal plane. Distinctly developed juxtaposition and interpenetration twins would, however, appear to be rare, for only a few isolated examples have hitherto been described.There are two twin-laws for corundum crystals, the twin-plane being either r (101̄l) = (100) or c (0001) = (111). The former of these is the one considered in the present note.
Potarite, a new mineral discovered by the late Sir John Harrison in British Guiana
Authors: Spencer L. J. 
Published: December 2006

The untimely death of Sir John B. Harrison on February 8, 1926, just as he was returning home after over forty-six years' service in the West Indian colonies; unfortunately prevented the publication by him of a complete account of the interesting new mineral which, as a result of much patient chemical work, he had discovered in British Guiana. As he had corresponded with me on this matter since April, 1924, and further, as this is the same mineral that I had myself erroneously described as 'allopalladium', I feel it my duty to place on record the full facts so far as can now be ascertained.I had suggested that the new mineral might be named after Sir John Harrison, but this he objected to ; and, in consultation with the Governor of British Guiana, he proposed the name potarite (letter of April 8, 1925), but he did not himself record this name in print.
Fictitious occurrences of iron silicide (ferrosilicon)
Authors: Spencer L. J. 
Published: December 2006

Ferrosilicon is occasionally found under circumstances that suggest that it is a natural mineral. Twice during the past quarter of a century it has been described as a new mineral, and the error was detected only after preliminary accounts had been published. It has also at times been thought to be meteoric. A supposed meteoric iron from North Carolina was described by C. U. Shepard in 1859 as composed of a material to which he gave the name 'ferrosilicine'.The following notes collected during several years contain nothing new. They are merely brought together to serve as a warning against an error that may recur.On several occasions between 1924 and 1929 Mr. H. N. G. Cobbe, a consulting mining engineer, sent to me for identification rounded pieces of a metallic substance that had been picked out from the concentrates of the gold dredgers on rivers and creeks in British Guiana.
The paragenesis of Cookeite and hydromuscovite associated with gold at Ogofau, Carmarthenshire
Authors: Brammall A. , Leech J. G. C. , Bannister F. A. 
Published: December 2006

This paper describes occurrences of cookeite (not previously recorded as a British species) and hydromuacovite, associated with auriferous pyrite and arsenopyrite, blende, galena, carbonates, and free gold at Ogofau, on the left bank of the river Cothi, half a mile ESE. of Pumpsaint, Carmarthenshire.The hillside around Ogofau is scarred with opencast workings and trenches reputed to be an 'ancient gold mine' dating back to Roman times. Though the mine is described as 'disused' on the Ordnance Survey map (six-inchcs/mile, Sheet XVII, NW.), these surface workings have been exploited for free gold intermittently within the last fifty years, and recent development work (by the Roman Deep Holdings,Ltd.) from a shaft sunk in 1910 is approaching the producing stage.
An integrating micrometer for the geometrical analysis of rocks
Authors: Dollar A. T. J. 
Published: December 2006

This instrument is a microscope stage-micrometer for the quantitative estimation of one to six different kinds of constituents in a substance, by the Delesse-Rosiwal method. It is intended, primarily, for linear micrometrie analysis in petrography, but has similar uses in mineralogy, chemistry, and metallography. Economic applications include the volumetric evaluation of components in building stones, road-metals, sSlid fuels, refractories, and slags.The object of this new design is to combine speed and accuracy in operation with a particularly compact construction, mechanical simplicity, and strength. Special consideration has been given to the wear and cleansing of bearings, the definition of scale-divisions and zero-marks, and the rigidity of all supports for moving parts.
Two new pyroxenes included in the system clinoenstatite, clinoferrosilite, diopside, and hedenbergite
Authors: Deer W. A. , Wager L. R. 
Published: December 2006

Two monoclinic pyroxenes from the Skaergaard Halvoen intrusion, Kangerdlugssuak, East Greenland, have been separated and analysed. They occur in a strongly differentiated gabbro complex which ranges from a hypersthene-olivine-gabbro at the base to a fayalite-quartz-gabbro of unique composition at the top. The differentiation has proceeded with a steady increase in iron and a corresponding decrease in magnesia, while the other major oxides remain relatively constant throughout. The clinopyroxenes in the lower horizons are in equilibrium with labradorite, normal olivine and hypersthene, and are fairly normal varieties as shown by the following optical properties:—(1)… α 1·672, β 1·678, γ 1·701, 2V 42°, γ: c 39°, sp. gr. 3·34.(2)… α 1·695, β 1·702, γ 1·722, 2V 43°, γ: c 41° sp. gr. 3·38.
Merosymmetry versus merohedrism
Authors: Rogers Austin F. 
Published: December 2006

While crystal classes based upon symmetry furnish a clear-cut classification of crystals free from ambiguity and uncertainty, there are cogent reasons for recognizing the larger groups called systems.It is important to recognize crystal systems, not only on account of physical properties, but also on account of the difficulty of assigning some crystals to their appropriate class. For example, a crystal consisting of a tetragonal prism and a pinakoid may belong to any one of seven classes. For the time being it is placed in the tetragonal system. When it is carefully investigated and its symmetry determined it may be assigned to the proper class.Contrary to statements that have been made, we can have, and do have, a two-fold classification in geometrical crystallography—the thirty-two classes based upon symmetry, and the six systems based upon properties that certain classes have in common.In the opinion of the writer the most satisfactory set of names for the crystal classes is the one based upon names of general forms. These names of Groth are comparatively simple, consistent, and lend themselves to international usage.
Some minerals from the leucite-rich rocks of the West Kimberley area, Western Australia
Authors: Prider Rex T. 
Published: December 2006

In the investigation of a suite of leucite-lamproites from the West Kimberley area of Western Australia, carried out in the Department of Mineralogy and Petrology, Cambridge, during the period 1937–38, a number of unusual minerals were noted. Three of these were isolated and analysed and two of them proved to be new species. The present paper deals mainly with the three minerals analysed. They are—(l)Magnophorite, a new amphibole allied to katophorite.(2)Wadeite, a new potassium-zirconinm silicate.(3)Titaniferous phlogopite.The leueite-bearing rocks occur at a number of isolated volcanic vents, nineteen of which have been examined and mapped by Dr. A. Wade. They have in every instance broken through sedimentary déposits of Permian age. Considerable diversity is to be seen in the rock types developed, but they are all characterized by high potash, magnesia, and titania, with low alumina and soda. Analyses of some types which indicate the general chemical character of these rocks are given in table I.
Tektites and silica-glass (With Plates XVI and XVII.)
Authors: Spencer L. J. 
Published: December 2006

The natural glasses recognized as tektites are characterized by their acidic composition, the silica percentage ranging from 68 to 80. Their origin is still a debatable point. Within this range glasses are known which have undoubtedly been produced by the fusion of siliceous terrestrial materials in the intense heat developed when large iron meteorites have struck the earth's surface; while others of the same origin show silica ranging up to 98 per cent., that is, an almost pure silica-glass.From a collection of 84 chemical analyses of tektites taken from the literature, only 36 (many of them due to A. Lacroix) give data for the specific gravity and refractive index which presumably were determined on the same sample of material as that analysed. These are reproduced in table I (arranged in order of silica percentages) and plotted in figs. 1 and 2. Corresponding with the range in SiO2 from 68·00 to 80·73% there is a nearly uniform decrease in d (2·498–2·339) and n (1·526–1·4867). The specific refractivity, K = (n−1)/d, varies from 0·2050 to 0·2107 (0·2258 in the case of no. 29 with the abnormally high n 1.5380).
A new method for the preparation of thin sections of clays
Authors: Weatherhead A. V. 
Published: December 2006

Thin sections of clays are not easily prepared by the routine petrographic methods. The chief difficulties are due to the extremely fine texture of the clays and to the soft and plastic nature of these materials. These difficulties are only too well known, and, although in some cases they have been partially overcome by impregnation in vacuo, it is safe to assume that really little work has been accomplished in the microscopic examination of clays on account of the difficulty of producing satisfactory thin sections. The writer has attempted to extend the scope of the microscopic investigation of clay rocLs by means of the technique outlined below.The method has been devised in response to an appeal by a friend, who, working in a laboratory at a well-known pottery works and thus connected with the clay industry, desired a method that would make possible the examination of thin sections of clays under high powers with polarized light.
A note on crystallographic calculations
Authors: Hey Max H. 
Published: December 2006

In the course of work on the Barker index of determinative crystallography, a number of interesting problems have arisen owing to the selection by a few workers of unusual sets of fundamental angles for their computations. Most of these problems have been of no general application, but One appears to have a wider interest and may prove of practical value in dealing with crystals having curved or striated faces that only admit of accurate measurements along one zone.This problem was to compute the angles and elements of a monoclinic crystal, using as fundamentals the angles from b(010) to any three faces e, f, g (of known indices) not in the zone [010], and no pair of which are co-zonal with b(fig. 1).
On maucherite (nickel-speiss, placodine, temiskamite) (With Plate XXIV.)
Authors: Peacock M. A. 
Published: December 2006

Nickel-Speiss (Nickelspeise), an impure arsenide of nickel obtained as a by-product in the manufacture of smalt, has long been known as a source of distinct crystals representing a definite chemical compound. Such crystals were already analysed by Döbereiner (1823), who concluded that the material was an artificial form of niccolite, NiAS. Later analyses showed that the composition of the crystallized furnace product approaches Ni3As2, a compound unknown in nature at that time.A substance corresponding to the crystallized nickel-speiss, but thought to be of natural origin, was first described by Breithaupt (1841), who named the material Plakodin (πλăκώδης, broad) in allusion to the tabular habit of the crystals. These were said to have occurred in the Jungfer mine at Müsen in Westphalia, associated with chalybite and gersdorffite and to have been salved by a smalt-works official from a shipment of ores.
Optical properties of olivines from Ubekendt Island, west Greenland
Authors: Game P. M. 
Published: December 2006

The olivines, which are the subject of this note, were obtained from a series of basaltic lavas and dikes on Ubekendt island, which lies off the west coast of Greenland in latitude 71 ° N., longitude 54 ° W.The optical properties of the olivines were investigated in order to determine any range in composition; such variations might have been expected in the very thick lava series. From this aspect, however, the results are disappointing, the composition range being small. However, it is thought that the results may have a certain interest in showing the relative accuracy obtainable in the measurement of refractive indices and optic axial angles. The usual determinative methods have been slightly varied. It is the purpose of this note to describe these variations and to compare the relative speed and scope of the method used with those obtained by other methods.
A nomogram for the law of direction-cosines
Authors: Tomkeieff S. I. 
Published: December 2006

If α, β, and γ are the three angles between a line passing through the origin and the three rectangular co-ordinate axes, then the equation connecting them is as follows:cos2α+cos2β+cos2γ = 1.This is the law of direction-cosines of a line. Substituting (cos 2α+1)/2 for cos2α, &c., we get:cos 2α+cos 2β+cos 2γ = −1.
An X-ray study of diamonds artificially prepared by J. B. Hannay in 1880 (With Plate X.)
Authors: Bannister F. A. , Lonsdale K. 
Published: December 2006

During the course of a general investigation by one of us (K. L.) of diamonds from various sources, using X-ray analytical methods, the inquiry arose as to whether so-called artificial diamonds had ever been examined in this way. It was found that there was, in the Mineral Department of the British Museum, a glass slide bearing 12 minute specimens, labelled as being diamond, artificially prepared and presented by Mr. J. B. Hannay in 1880, presumably the remainder of those investigated by Prof. N. Story-Maskelyne, and referred to in a letter to the Editor of The Times which appeared in that paper on February 20, 1880, as follows:Sir,—A few weeks since I had to proclaim the failure of one attempt to produce the diamond in a chemical laboratory. To-day I ask a little space in one of your columns in order to announce the entire success of such an attempt by another Glasgow gentleman.
Banalsite, a new barium-felspar from Wales
Authors: Smith W. Campbell , Bannister F. A. , Hey Max H. 
Published: December 2006

In 1941 the Home Ore Department of Iron and Steel Control, Ministry of Supply, took over the old Benallt manganese mine at Rhiw in the Lleyn Peninsula, Carnarvonshire. A new shaft was sunk and a new mine was developed among and mainly below the old workings. It was in one of the old workings of Benallt that Mr. (now Sir) Arthur Russell discovered in 1911 the well-crystallized specimens of celsian and paracelsian recently described by Dr. L. J. Spencer.Dr. A. W. Groves of the Mineral Resources Department of the Imperial Institute and geologist to the Home Ore Department had had a sharp look-out kept for the reappearance of the barium-felspars in the new workings, and when thin bands of coarsely crystallized but compact, white ‘sparry’ minerals were found in one of the ore-bodies he sent specimens to the Department of Mineralogy of the British Museum for investigation.
The lattice parameters of α-alumina and chromic oxide
Authors: Jay A. H. , Wilde W. T. 
Published: December 2006

During the course of a study of the interaction of certain pure refractory oxides at high temperatures it became necessary to obtain accurate values for the lattice parameters of α-alumina and chromic oxide. Values obtained by previous workers, listed in table I, did not attain a greater accuracy than one part in 2000, whereas the use of large-diameter powder cameras calibrated with quartz now yield lattice parameters accurate to at least one part in 30,000.Samples of the calcined oxides were examined in a 19 cm. diameter powder camera, alumina with cobalt Kα radiation and chromic oxide with chromium Kα radiation. Results are given in tables II and III.
Notes on the mineral deposits of the Teign valley, Devon
Authors: Ramsden J. V. 
Published: December 2006

Research into the history of the old mines suggests that two mineralized fissuring systems intersect in central Devon, often carrying commercial ore-bodies. The older of these is the east-west system usually carrying copper, iron, or tin, which has been extensively worked in west Devon, but is less developed on the eastern flank of the Dartmoor granite massif.The younger north-south series, characterized by its lead and silver ores and baryte is particularly well developed in the Teign valley. This band of mineralization can be traced from the north of Scotland through Brittany and Spain to Algeria. In Devon it appears to be divided into three main fissure bands:1.Combe Martin to Plymouth.2.North Molton to Spreyton, with a possible extension south of the Dartmoor granite.3.Molland to Newton St. Cyres and the Teign valley.
The shape of reflections on X-ray, single-crystal photographs (With Plates X and XI)
Authors: Lonsdale Kathleen 
Published: December 2006

In the early days of X-ray crystallography the study of the atomic and molecular structure of crystals was of primary importance. It was more necessary to know the arrangement of the atoms in, say, rocksalt, quartz, diamond, or graphite, than to know the exact distances apart of the atoms, or the small deviations from the mean atomic structure which may result from heat movements, eccentricity of growth, mechanical distortion, and other factors.Now, however, the range of problems is widening, and X-ray methods are being used as a research tool by many workers whose main interest is in other branches of science. It is necessary, therefore, to point out that the familiar Bragg law, nλ = 2d sin θ, which relates order of spectrum n, wave-length λ, crystal spacing d, and diffraction angle θ in an ideal crystal, though still of course applicable, must be applied with some caution to crystals which are not ideal in either structure or texture, and which may be of irregular or eccentric shape.
On the petrology of the ultrabasic and basic plutonic rocks of the Isle of Rum
Authors: Tomkeieff S. I. 
Published: December 2006

The Isle of Rum contains one of the most interesting assemblages of plutonic rocks of Tertiary age in the British Isles. The pioneer work of Macculloch and the later exploratory efforts of Judd and Geikie were followed by an admirable account of the rocks by Harker, given with his usual lucidity and precision. In 1938 I spent a fortnight on this island, and this paper—the outcome of my visit—aims merely at supplementing Harker's petrographical description by certain quantitative data in respect of the ultrabasic and basic rocks found there and of recording certain observations relating to the igneous tectonics.The earliest phase of igneous activity on Rum was the eruption of doleritic and mugearitic lavas. As shown by Bailey the eruptive phase of igneous activity was followed or accompanied by the formation of a ring-fault and two subordinate vents iufilted with explosive breccia and intruded by felsite. The space inside the ring-fault was then intruded by a banded peridotite-allivalite complex and later by eucrite in the form of a semicircular ring-dike and associated sheets. Finally, a granophyre boss was intruded along the western side of the ultrabasic-basic complex.