bluuebunny/crossref_metadata_2025_split huggingface dataset:
The progressive illitization of interstratified illite-smectite from Carboniferous sediments of Northern England and its relationship to organic maturity indicators
Authors: Smart G. , Clayton T. 
Published: December 2006

AbstractInterstratified illite-smectites from Carboniferous sediments from the Alston and Askrigg blocks and the intervening Stainmore trough of the northern Pennines, UK, were examined by XRD. Both blocks are underlain by Caledonian granites. During late Carboniferous times sediments overlying the Alston block were intruded by the Whin Sill. The percentage smectite in illite-smectite (%S in I/S) varies from ∼35% to <5% only homogeneous mudstones give consistent results. In the case of the Askrigg block and Stainmore trough, a good inverse correlation was found between %S in I/S and vitrinite reflectance. Both illitization of illite-smectite and vitrinite reflectance increase towards the centre of the block. This is thought to be related to high heat-flow centred about the granite basement. In the case of the Alston block, there is no direct relationship between clay and vitrinite data, vitrinite reflectance being controlled by the position and thickness of the Whin Sill. Except where close to the contact, the Whin Sill had no apparent effect on %S in I/S. As observed for the Askrigg block, %S in I/S is directly related to the position of the underlying granite. The progressive illitization of illite-smectites of low expandability is very slow when compared to vitrinite alteration in response to rapidly increasing temperature. Consequently, %S in I/S is a potential indicator of thermal maturation in situations where vitrinites, by virtue of their rapid response to increasing temperatures, fail to provide a regional view of heat-flow patterns.
The use of RbCl disks for the infrared spectroscopy detection of hydrated and dehydrated halloysite in mixtures with kaolinite
Authors: Mendelovici E. , Sagarzazu A. 
Published: December 2006

AbstractA simple IR spectroscopy method for detecting hydrated and dehydrated halloysite in artificial mixtures with kaolinite is described. The method is based on the exclusive ability of RbCl among the alkali halides to form a complex with halloysite but not with kaolinite. This complex absorbs at 3500 cm−1 when hydrated halloysite or admixed halloysite is examined in RbCl disks, the limit of detection being 15% in the kaolin admixture. Heating the clay powders or corresponding RbCl disks at 110°C affects the 3500 cm−1 frequency. The development of this absorption band together with a decrease in the intensity ratio of the 3690/3620 cm−1 frequencies is proportional to increasing amounts of halloysite in the kaolin admixtures. This method has an analytical applicability and is relatively rapid.
Some observations on pleochroism and idiophany in mineral plates
Authors: Crook T. 
Published: December 2006

In this paper an attempt is made to state and explain, in a simple manner, the essential features of the phenomena which are seen when plates of pleochroie minerals are examined in ordinary light.The pleochroie effects exhibited by minerals are usually studied in light of practically normal incidence. For the observation of facial colours, transparent crystals, or, better still, specially orientated cube-shaped pieces of minerals, are examined in ordinary light. In general, by this mode of observation, only facial colours are seen when ordinary light is used, and for the observation of axial colours the incident light must be polarized.
Note on some artificially-produced crystals of Gypsum
Authors: Fletcher Mark 
Published: December 2006

Professor H. Louis, of Armstrong College, handed over to me for examination some crystals of gypsum which had been sent to him by Mr. Frank E. Lott, A.R.S.M., F.I.C., of Burton-on-Trent. Mr. Lott has kindly furnished me with the following particulars.The crystals were deposited in an apparatus employed for raising steam in the production of distilled water. This apparatus consists of a copper vessel enclosing steel steam pipes for heating the water. The crystals were deposited on the walls of the copper vessel and on the steel pipes, and had been formed within a period of twelve months.
A diagram for use with the total-reflectometer
Authors: Hutchinson A. 
Published: December 2006

The accompanying diagram (Plate VIII) has been prepared in order to facilitate the determination of indices of refraction with the Kohlrausch total-reflectometer, by affording a means of rapidly werking out the results by a graphical method.The Kohlrausch instrument enables measurements to be made of the critical angle θ, at which total reflection begins, when monochromatic light is reflected at the plane surface of a solid of refractive index μ immersed in a liquid of higher refractive index μ′.
Optically uniaxial Augite from Mull
Authors: Hallimond A. F. 
Published: December 2006

The mineral hero described was recently collected by the officers of the Geological Survey during their work for the six-inch map of the Island of Mull. It is present as minute phenocrysts in a dark, glassy, magnetite-bearing rock/which is intruded as sheets in the Tertiary lavas nearly one mile south-south-west of Pennygael.The small rounded crystals of augite are seldom more than ½ mm. in diameter and are traversed by irregular cracks. They contain a few negative crystals, and are occasionally darkened, probably with included magnetite. They appear to have been reabsorbed to some extent by the matrix.
Sur une propriété numérique de l'ensemble des axes de symétrie situés dans les plans de symétrie d'un polyèdre
Authors: Cesàro G. 
Published: December 2006

Les axes de symétrie d'un polyèdre ne sont pas toujours situés tous dans ses plans de symétrie ; ainsi, tandis que le cube a tous ses axessitués dans ses plans de symétrie, le rhomboédrea son ʌ3 situé dans des plans de symétrie, tandis que les 3L2 ne sont pas situés darts ces plans.
The dispersion phenomena of some monoclinic Felspars
Authors: Kôzu K. 
Published: December 2006

In the present paper the dispersion of the refractive indices of monoelinie felspars from four different localities is given, likewise that of the optic axial angle and of the optic axes in some of them.The method of investigation and instruments for these studies have been already mentioned in my previous paper. As the refractive indices and dispersion of the glass hemisphere of the total-reflectometer have not so far been given, I shall in the first place state the way in which they have been determined and their values and the degree of accuracy attainable, for the dispersion of the glass hemisphere differs to au appreciable degree from that of other instruments of the same kind.
Palaeophysiology : the organic origin of some minerals occurring in sedimentary rocks
Authors: Samoilov J. V. 
Published: December 2006

During the last few years I have applied myself to the study of some minerals occurring in the sedimentary rocks of a definite geological horizon. The success of my investigations was greatly favoured by the fact that the mineralogical material was collected during the course of the systematic geological exploration of the phosphate deposits of Russia, which during the past eight years has been under my immediate supervision.The explorations just mentioned were begun in the north-eastern part of European Russia, and several occurrences of barite were found in the first year during the field study of the phosphate deposits in the government of Kostroma.
The relation between different laws of twinning that result in the same twin-crystal
Authors: Evans John William 
Published: December 2006

In the following notes I have endeavoured to give in a convenient and simple form a complete account of the relations connecting different twinning-laws or operations, which, when applied to the same crystal-structure, produce indistinguishable results.A rigorous analysis of the possible relations between the compound structures of twin-crystals, based on the principles of the equality of the structural distances in the plane of composition, will be found in the author's papers, ' The geometry of twin-crystals' (Proc. Roy. Soc. Edinburgh, 1912-1918, vol. xxxii, pp. 416-432, 433-457) and 'Die Geometrie der Zwillingskrystalle' (Zeits. Kryst. Min., 1918, vol. lii, pp. 827-371). See also the paper 'Twin-planes and cross-planes' in this Magazine (1910, vol. xv, pp. 390-397).
On some crystallized sulphates from the province of Huelva, Spain
Authors: Collins Henry F. 
Published: December 2006

The occurrence of melanterite, pisanite, and chalcanthite as secondary minerals resulting from the oxidation of pyrites masses containing copper is well known. It is not so well known that other metallic sulphates are from time to time found, and a brief description of the mode of occurrence of a few of these, in addition to some details of the composition of pisanite and chalcanflSte, may be of interest.Pisanite.—This mineral is of common occurrence at all the pyrites mines of Huelva and elsewhere, ibrming stalactites and stalagmites in those parts of the mines that are above drainage level though subject to more or less percolation of water. It is rarely found as well-formed crystals, save occasionally when a pool ef strong sulphate water has been temporarily dammed hack in some way, and then supersaturated through evaporation.
The Dartmoor granite: its mineralogy, structure, and petrology
Authors: Brammall Alfred , Harwood H. F. 
Published: December 2006

This paper continues the study of the constituent minerals of the Dartmoor granite. The district to which it mainly refers comprises the for-area around Widecombe and a part of the aureole adjoining. No detailed reference will be made at this stage to aureole phenomena. The results to be recorded necessitate a brief description of the two main granite types and of their field relationships. Abundant varieties and modifications of both types occur, but for the Purposes of the present paper they are of subordinate importance.Most of the for-masses and high-level exposures of granite in the area consist in the main of the type known locally as the ‘giant granite‘ — a very coarse-grained, strongly porphyritic roelc rich in biotite, and consistently garnetiferous; it has an index-figure 1 ranging from 7.5 to 12.
On a peculiar chlorite-rock at Ible, Derbyshire
Authors: Garnett Cecil S. 
Published: December 2006

In this paper is described an apparently hitherto scientifically unnoticed mode of alteration of olivine-dolerite in the intrusive sill at Ible near Matlock.The igneous rocks of Derbyshire, locally called ‘toadstones’, constitute a well-known basic series of both contemporaneous and intrusive rocks. They comprise lava-flows, sills, a few thin dikes, agglomerates, and tufts. All occur in beds of Lower Carhoniferous age, and are confined to the upper half of the known thickness of the Carboniferous Limestone, with, in the south of the county, the overlying Limestone Shales. They have been described, in recent years, by Sir A. Geikie (‘Ancient Volcanoes of Great Britain’, 1897, vol. 2); II. H. Arnold-Bemrose (Quart. Journ. Geol. Sot., 1894, vol. 50, pp. 603-644; 1907, vol. 63, p. 241, et seq.); and H. C. Sargent (ibid., 1918, vol. 73, pp. 11-25).
Topaz from Cornwall, with an account of its localities
Authors: Russell Arthur 
Published: December 2006

Topaz, so common an accessory in tin lodes in all parts of the world, has hitherto been looked upon as comparatively rare in Cornwall. When massive, or even in the form of small, well-developed crystals, it is a mineral easily overlooked, or apt cursorily to be mistakcn for quartz.The presence of topaz as a microscopic accessory in granite, greisen, and rarely elvans, from most of the Cornish masses, has been determined by Dr. J. S. Flett in the course of the work of the Geological Survey; while the late Mr. J. H. Collins was responsible for the record of other interesting localities.In the present notes I have collected all the available information respecting its mode of occurrence and localities ; and have added several new ones, at some of which the mineral occurs in considerable mass, thus affording evidence that topaz is in Cornwall, as in the case of other countries, a comparatively common associate of cassiterite and wolframite, both in granite and sedimentary rocks.
Biographical notices of mineralogists recently deceased. (Second series)
Authors: Spencer L. J. 
Published: December 2006

Short biographical notices of persons interested in scientific mineralogy have been given in this Magazine since 1876. In the last volume these were more systematically collected together and indexed for convenience of reference and permanent record. For a continuation of this series the various details have been collected and filed during the past three years. I have to thank several foreign correspondents for kindly supplying some of the less readily accessible information; in particular, Professor P. N. Chirvinsky, of Novocherkassk in the Don region.The present list includes 55 haines, for 49 of which dates of birth and death, or ages, are here recorded. Including these with the 254 previously recorded in this Magazine, the total is 308 lives for which ages are known. The average age for these 303 lives of mineralogists is 64 years.
On the chemical classification of the mica group. I. The acid micas
Authors: Hallimond A. F. 
Published: December 2006

In a discussion of the composition of glauconite, it was shown that the analyses of this substance can be represented in terms of simple molecular proportions, provided that the mineral is regarded as a mixture of a silicate containing the group R2O3 with a similar compound in which one equivalent of R2O8 is replaced with one equivalent of RO; the general formula being R2O. 4(R2O3, RO). 10SiO2. nH2O.Work on the sedimentary iron ores collected during the preparation of the ‘Special Reports on Mineral Resources’, recently issued by the Geological Survey, made it necessary to review the composition of some of the chlorites ; but no evidence of similar replacement was found among the better-known minerals of that group.
Tourmalinization in the Dartmoor granite
Authors: Brammall A. , Harwood H. F. 
Published: December 2006

On the basis of field relationships, the main types of the Dartmoor granite can be referred to four stages of intrusion, the sequence being from relatively basic to thoroughly acid.To this sequence is closely related an increase in the content of tourmaline and in the extent to which autopneumatolysis (with tourmalinization) was effective before solidification of the rock was complete.Autopneumatolysis is well displayed by many minor intrusions referred to the latest stage. Such an intrusive rock is reddened more or less uniformly throughout its entire mass, and volatile constituents exhaled from its margin have reddened a contact-zone of the grey granite into which it is intrusive.
Illustration and detection of inclined and horizontal dispersion in biaxial crystals
Authors: Wilberforce L. R. 
Published: December 2006

As it is not always easy to obtain for the use of students suitable specimens of crystals which exhibit inclined or horizontal dispersion of the mean lines to a marked extent, a ready method of artificially producing optic pictures which show the appearances characteristic of these dispersions may be found of service by teachers.It is ohvious that, if the optic picture of an ordinary biaxial crystal is viewed or projected through a prism whose refracting edge is either parallel or perpendicular to the axial plane of the crystal, the dispersion produced by the prism will displace the components of the optic picture due to the various colours of the spectrum through distances increasing from red to violet, and will thus reproduce the phenomena of horizontal and inclined dispersion respectively.
The use of alignment charts in crystal-optics
Authors: Hutchinson A. 
Published: December 2006

The widespread use of methods based oil total-reflection for finding the refractive indices of crystals either directly, by the Abbe-Czapski crystal reflectometer or by the Kohlrausch method, or indirectly by means of liquid mixture of known refractive intex which require to be verified and standardized from time to time, renders desirable a rapid graphical method of ascertaining with some accuracy the index of the substance under test, direct from the instrumental data without calculation.An attempt in this direction was made by the author some years ago. The equation to be solved is n' = n sin θ, where n' is the index to be found, n that of the glass hemisphere, prism, or highly refracting liquid employed in the total-reflectometer, and θ the critical angle of total-reflection observed.
Gold and silver in the Dartmoor granite
Authors: Brammall A. 
Published: December 2006

Gold and silver have been detected not only in the peculiar facies of the granite occurring on Bittleford Down, but also in the normal grey biotite-granite of numerous tor- and quarry-localities; several hand-specimens of granite showing minute flakes of visible gold have been collected.The modes of occurrence of gold on Dartmoor, the environment of the granite from which specimens showing visible gold have been taken, and the gold-silver content of the granite generally have been investigated in some detail, with the results described below.
Some mineralogical transformations in crystalline schists
Authors: Tilley C. E. 
Published: December 2006

The twofold division of metamorphic rock-series into (a) Isophysical rock-series and (b) Isochemical rock-series, as proposed by P. Niggli in his paper, 'Die Gesteinsassoziationen und ihre Entstehung', introduces into metamorphic petrology two very useful terms, which will be of service in the metamorphic researches that await the attention of the petrologist.Among such investigated rock-series one may call to mind the studies on the chloritoid-schists of the St. Gotthard massif," the glaucophaneschist suite of the Bagne valley (Wallis), the calc-silicate series of the Trondhjem region, the contact rocks of the Kristiania and Comrie areas. Of these the last are particularly illustrative of an isophysical rock-series, wherein a chemically wide group of assemblages conforming to the composition of shale-limestone sediments is represented in the free-silica and quartzless hornfelses.
Rotating crystal X-Ray photographs
Authors: Greenwood Gilbert 
Published: December 2006

Since the original experiments of M. von Laue on the diffraction of X-rays by crystals, other and more suitable methods of research have been devised. The Bragg ionization-chamber method and the Debye-Scherrer powder method are now quite well known. The newest technique is that of the so-called 'rotating crystal', which is based essentially on some experiments of M. de Broglie. This method was first employed and developed in the Kaiser Wilhehm Institut für Faserstoffchemie in Berlin. It has recently been extended by the work of J. D. Bernal in the Royal Institution in London.There are two methods of making this type of photograph. In both a small crystal is rotated in a beam of X-rays and the reflected beams recorded photographically, in one case on a flat plate, and in the other on a cylindrical film the axis of which coincides with the axis about which the crystal is rotated.
A new model refractometer for determining the refractive indices of gem-stones, crystals, and liquids
Authors: Tully Bristow J. 
Published: December 2006

The general outline and weight of the body of the instrument are devised to ensure perfect rigidity and steadiness during use, all necessary adjustments, such as the focusing of the rotating eyepiece, movement of the revolving stage, reflector, or screen, being quite independent of the optical system; which, being contained in the main body in a dust-proof receptacle, entirely prevents any vital part of the refractometer getting out of adjustment, unless deliberately tampered with.The eyepiece, which by rotation is capable of giving a wide variation of focus, is set at the most convenient angle to ensure easy and comfortable observation.The forward projecting portion attached to the main body is rectangular in shape, and hollow, the upper surface forming a platform in which revolves a circular plated stage with a milled edge capable of being turned about a vertical axis through 360°, with an engraved scale marked at every 45° to enable the observer to read with accuracy the least and greatest refractive indices of all doubly refracting stones.
Vote on the alkali-lavas of Mount Nimrud, Armenia
Authors: Prior G. T. 
Published: December 2006

The object of this note is not to give elaborate descriptions of rocksections, but to call attention to tile fact that the old volcano of Nimrud, situated on the west side of lake Van in Armenia, was the centre of eruption of alkali-lavas presenting striking similarities to some of the alkali-rocks of the tlift Valley in East Africa.To Dr. Felix Oswald, in his book on the geology of Armenia, we owe a detailed description of this ancient volcano, of which the vast crater, now half occupied by a deep lake, is more than five miles across. An interesting series of the lavas from the volcano was collected by Dr. Oswald and was presented by him to the British Museum. On looking over thin slices of these rocks under the microscope, I was at once struck by the surprising resemblance of some of them, with their phenocrysts of anorthoclase and scattered tufts of aegirine and the soda-amphiboles, riebeckite and cossyrite, to rocks in Prof. J. W. Gregory's collection from the Rift Valley which I had described.
The age and composition of the Whin Sill and the related dikes of the north of England
Authors: Holmes Arthur , Harwood H. F. 
Published: December 2006

The system of intrusive sheets in the Lower Carboniferous formations of the north of England, familiar to geologists throughout the world as the Great Whin Sill, has a voluminous early literature which it is unnecessary to summarize here. It will be sufficient to refer to the classical papers by Topley and Lebour on the field relationships (1) and by Teall on the detailed petrography (4), each of which contains an ample bibliography of the earlier literature. The most recent general account is by Prof. E. J. Garwood (9), who contributed a careful discussion of the evidence bearing on the period of intrusion.Teall's great paper closely followed on one devoted to some of the dikes of the north of England (3), and in it he drew attention to the remarkable petrographical Similarity between the rocks of the Heft and High Green dikes and that of the Whin Sill (4, p. 656).
Notes on British barytes
Authors: Sweet Jessie M. 
Published: December 2006

When the slip catalogue of the barytes specimens in the British Museum collection was in the course of preparation, a few observations were made which may be of sufficient importance to place on record.The lists of localities of the barium minerals, barytes, witherite, alstonite, and barytocalcite, in the collection show that rather more than half of the specimens (573 out of 975) come from the British Isles. Hence it would seem that there is a special concentration of these minerals in this part of the world. Possibly this is fictitious, as the collection cannot be considered to be completely representative.