bluuebunny/crossref_metadata_2025_split huggingface dataset:
Note on the determination of the optic axial angle of a crystal in thin-section by the Mallard-Becke method
Authors: Collingridge Harvey 
Published: December 2006

Mallard's original method was based on the measurement of the linear distance, as determined by an eyepiece-micrometer, between the optic axes in a section of the crystal at right angles to the acute biseetrix viewed in convergent light.Professor F. Becke implored on this method by utilizing sections which were not at right angles to the acute hissetrix, but in which both optic axes were visible in the field. He projected both axes by means of an Abbe camera lucida on to a revolving drawing-table, and by means of the Mallard equation plotted the axes on a stereographic projection and thus obtained the optic axial angle, the angles of course being corrected for refraction to the true angles in the crystal section. Professor Becke subsequently, by utilizing the Biot-Fresnel law, formulated a graphic method of obtaining the optic axial angle from a section in which only one axis was visible.
The Meteoric Stones of Baroti, Punjab, India, and Wittekrantz, South Africa
Authors: Prior G. T. 
Published: December 2006

In 1912 Mr. N. B. Kinnear, Curator of the Bombay Natural History Society's Museum, brought to me at the British Museum, for identification, a specimen of a supposed meteorite which had been sent to the Bombay Natural History Society by the late General W. Osborn.General Osborn stated that, in November, 1910, on arrival at his usual winter quarters in the hill station of Kotheir in the Punjab, he visited his friend, the Rajah of Bilaspur, who presented him with a fragment, weighing about a quarter of a pound, of a meteorite which had fallen in daylight at the village of Baroti, in the Bilaspur (Simla) district, one day during the month of September, 1910.
The genetic classification of rocks and ore deposits
Authors: Crook T. 
Published: December 2006

During the last decade there has been no lack of controversy on the subject of rock classification, but the dispute has concerned igneous rocks almost entirely. Petrography has been threatened by an effort to reduce it to an independent science of igneous rocks, and in consequence of this there has been a tendency to neglect its wider aspects. Important as igneous rocks are, their formation is less well understood than is that of some other sub-groups of rocks ; moreover, they constitute one only of some six or seven sub-groups, and it is the business of petrography as a science to deal with these rocks as a whole. The student of petrography should be encouraged to take this wider view. He shonld look at these different sub-groups of rocks in their proper geological perspective, and approach the study of the classification of igneous rocks with a knowledge of the principles that are applicable to the classification of rocks as a whole.The discussion concerning the classification of ore deposits has proceeded on independent lines, and in a more well-balanced manner than has that of rocks. With ore deposits, as with rocks generally, genetic principles have triumphed; but the application of these principles to rocks long preceded their application to ore deposits. Iu recent years it has become apparent that the fundamental requirements for the classification of rocks and ore deposits are essentially the same ; and in view of the identity of their interests, both subjects are treated in this paper.The aims of this paper are : To define the basis of genetic classification ; to give a brief historical account of classification on genetic-geological principles ; to point out defects in the present system of arrangement ; and to suggest an altemmtive scheme of grouping that is in closer accord with geological and genetic principles.
New crystal-forms on Pyrites, Calcite, and Epidote
Authors: Spencer L. J. 
Published: December 2006

The dyakis-dodecahedron (641) was observed on certain of the Museum specimens by Mr. Richard Elliot Steel in 1879 and again by myself in 1894; and although several memoirs on the crystallography of pyrites have been published since those dates, this form has not hitherto been recorded for the mineral.Under the register-number 31679 are a number of small specimens and isolated crystals of pyrites, on three of which the form in question is deve]opod. These were purchased in 1860, and their locality is unknown. They show some matrix of black shale, and, unfortunately, are gradually being broken up by decomposition.
The fibrous Gypsum of Nottinghamshire
Authors: Alfred Richardson W. 
Published: December 2006

SummaryThe Upper Triassic sediments are assumed to have contained concentrated solutions, which caused, or contributed to, their dehydration and contraction. The contraction of a colloidal mass results in the production of tension planes, and unless compensated by settlement, rupture finally ensues. Relief of pressure by rupture may bring the sohtions into the labile state, when innumerable closely-spaced centres of crystallization will be set up. The crystals, fed by vertically diffusing solutions, grow vertically, so long as contraction and feeding continue. When, at length, contraction attains its limit, further growth is resisted, and the stresses set up, transmitted to the central parting, produce bending and other pressure effects in the veins.
On Glauconite from the Greensand near Lewes, Sussex; the constitution of Glauconite
Authors: Hallimond A. F. 
Published: December 2006

A Boring male at Iford Manor, 1½ miles S.E. of Lewes, Sussex, yieled the following section:The lower sand contained numerous grains of glauconite, while the upper bed was black when wet and consisted almost entirely of dark-green glauconite, with a few shell fragments and large quartz grains. The glauconite grains were small and were separated in an almost pure state by sieving; the portion coarser than 76 [wires to the inch] mesh contained the shell fragments, &c., while that below was nearly all glauconite, with a few very small grains of magnetite present in the sand.
The occurrence of rutile, brookite, and anatase on Dartmoor
Authors: Brammall Alfred , Hardwood H. F. 
Published: December 2006

The occurrence of brookite aud anatase within the limits of the Dartmoor granite exposure was first indicated by a sample of stream-sand taken two years ago below the bridge at Dartmeet–a locality which is noteworthy for sands rich ill these and other accessory minerals of the Dartmoor granite.Anatase, either alone or associated with brookite in small amounts, was found in a majority of the sands taken the following year at selected points along (1) the Plym River, between Cadover Bridge and Hatter Tor, (2) the East Dart and the West Dart, upstream from Dartmeet, (3) the West Webburn, upstream from Ponsworthy, (4) the East Webburn, upstream from Lizwell Meet, and (5) minor streams in the Hamel Down-Bonehill Down area. Rutile proved to be a rare mineral, liable to be overlooked in a residue containing brown cassiterite, from which it cannot readily be distinguished except by microchemical means.
The occurrence of a gold-bearing pegmatite on Dartmoor
Authors: Brammall A. , Harwood H. F. 
Published: December 2006

A Remarkable pegmatite occurring on Bittleford Down (Wind Tor), near Widecombe, is described in the Survey Memoir as a veinrock containing (a) abundant hornblende, a mineral not previously found in any of the post-Carboniferous granites of the west of England, (b) much sphene, (c) porphyritic crystals of oligoclase, and (d) quartz crowded with fluid inclusions.This rock is of peculiar interest in other respects. Its complete freedom from biotite and its high content of felspar (oligoclase dominant over orthoclase) imply considerable deviation in bulk composition from the normal Dartmoor granite. Moreover, its accessory minerals include both gold and silver.Considered broadly as a coarse-grained felsic type, its position in the list of variants from the normal granite is shared by a still more felsic rock with which it is closely associated in the field.
Calcite crystals from Holywell, North Wales
Authors: Mountain E. D. 
Published: December 2006

In September 1923 a visit to the lead-mining district of Holywell, Flintshire, so closely associated with the name of Thomas Pennant, was organized by Mr. Campbell Smith in order to examine the abandoned workings with a view to collecting specimens. The occurrence of the ores has been described in detail by Sir Aubrey Strahan and Mr. Bernard Smith, and reference to many mineral localities, mentioned by Pennant, is made by Mr. Campbell Smith (loc. cit.).The commoner specimens collected consist of ruby-blende (Talargoch mine), botryoidal and pseudomorphous calamine ZnCO3 (Milwr mine), orange and reddish-mauve fluor with bitumen and blende (Bryn-gwiog mine).Calcite also occurs abundantly in veins and cavities throughout the limestone, the crystals usually consisting of large modified obtuse rhombohedra.
The chemical composition and optical properties of a basaltic hornblende from Hungary
Authors: Vendl Miklós 
Published: December 2006

Although there is an extensive literature on the amphiboles, especially those of the monoclinie series, there appear to be only few records for basaltic hornblendes in which the physical properties and the chemical composition have been determined in detail on the same sample of material, Mention may be made of the later papers by S. L. Penfield and F. C. Stanley, S. Kreutz, W. E. Ford, and H. Küchler.The basaltic hornblende described in the present paper is found in the volcanic tuff-breceias of Pliocene age in the neighbourhood of Lake Balaton. The locality is near the small village of Balatonesicso on the southern slope of the ‘Fenyves’ hill, the top of which is capped with basalt. Tile hornblende is found as loose crystals in the tuff-breccia and also in blocks rich in olivine. Specimens of some size, up to 2 or 3 cm. in length, may be collected.
On a compact chlorite from Bernstein, Austria
Authors: Campbell Smith W. 
Published: December 2006

The material which is the subject of the present note was presented to the British Museum (Natural History) in November 1923, by Captain Eric C. Palmer, of the Styrian Jade Company, Bernstein, Burgenland, Austria. Bernstein is situated 92 kilometres south of Vienna, on the present borders of Styria and Upper Austria, and 22 kilometres west of the frontier town of Guns. Previous to the Treaty of Versailles, Bernstein was in Hungary, Comitat Vas (Eisenburg). Its Hungarian name is Borostytánkő.In 1854, Johann Cžjžek, in a paper entitled ‘Das Rosaliengebirge und der Wechsel in Niederösterreich’, had described the geology of the district, and given some account of the rocks, including a description of the occurrence at Bernstein of serpentine in the midst of an area of hornblende-schists, chlorite-schists, and gneiss.
On the nature of Berthierite
Authors: Stillwell F. L. 
Published: December 2006

Six analyses of berthierite from various localities are quoted by Dana and show a varying composition. The analyses correspond approximately to the formulae FeS.Sb2S3, 3FeS.2Sb2S3, and 3FeS.4Sb2S3. It is considered by Dana that the variation is probably due to the impurity of the analysed material and that the composition of berthierite is probably FeS. Sb2S3. This view is supported by the examination and analysis of a specimen of berthierite from Xullarnanna, 18 miles north of Inverell, Now South Wales.The specimen was kindly lent by Mr. G. W. Card, Curator of the Mining Museum, Sydney, for comparison with certain minerals under investigation, and measured approximately l x l x O-7 cm. It was sliced and one portion was polished for examination under the reflecting microscope while the other portion was used for the chemical analysis.
On the occurrence of the rare mineral nadorite in Cornwall, and of beraunite in Co. Cork, Ireland
Authors: Russell Arthur 
Published: December 2006

The rare mineral nadorite has hitherto been recorded from one locality only, namely, Jebel Nador in the province of Constantine, Algeria, where at one time it was found in considerable quantity associated with bindheimite, smithsonite, and galena in a deposit lying between lacustrine limestone and brown marl.In the present notes I am able to record the occurrence of this mineral at the small antimony mine of Bodannon, St. Endellion, Cornwall, where I found a single specimen in 1907. Immediately after the reading of this paper, Professor A. Hutchinson of Cambridge most kindly sent me a specimen for examination which he had himself collected from the small dump at Bodannon in 1919, and this mineral, which had attracted his attention, also proved to be nadorite.
Petrology of the Bodmin Moor granite (eastern part), Cornwall
Authors: Ghosh P. K. 
Published: December 2006

This paper presents the results of an investigation of the granite composing the eastern part of Bodmin Moor, Cornwall, as mapped on Sheet no. 337 of the Geological Survey. The work was undertaken on the suggestion of Dr. J.W. Evans, and comprised the field- and laboratory-work necessary for a detailed study of the petrology and tectonics of the area.The boundary of the granite, as mapped by the Geological Survey, has been retained, and also the distribution of the two main granite types ('coarse' and 'fine') shown on the Survey map. The coarse granite, however, has been sub-divided into two varieties, and it has been found practicable to map the distribution of each (fig. 1).The killas inclusions in this granite have not hitherto been studied, and these have received due attention. Similarly, the minor intrusions described include some that have not been previously recorded.
On the biotite-bearing greenstones and on a rhyolitic pumice in the metamorphic aureole of the Falmouth granite
Authors: Ghosh P. K. 
Published: December 2006

In the metamorphic aureole of the Falmouth. granite, the greenstones I which are largely referable to epidiorites form an important and interesting assemblage of rocks. These are lower Palaeozoic in age and are pre-granite and have suffered from metamorphism as all effect of the granite-intrusion in post-Carboniferous times.The chief mineral constituents, viz. hornblende and plagioclase, are quite normal for a rock of this nature except that the former is clearly a derivative of augite, many relics of which are still preserved ; among the most important accessory minerals are biotite, chlorite, epidote, iron-ores, quartz, augite, axinite, and garnet. One may pass over some of the accessories as being quite usual, being partly primary and partly secondary in origin, but biotite is one of those the presence of which requires to be specially explained.
Colour reactions in the micro-chemical determination of minerals
Authors: Watson J. Adam 
Published: December 2006

The rapid determination of the chemical elements present in a mineral has been a desideratum ever since minerals became of economic use. Various methods have been employed, starting with blowpipe work, which in the early days proved of great value, especially in experienced hands, With the development of chemistry and the discovery of new elements, this process was largely abandoned in favour of the standard ' wet method' of chemical analysis. Later on, micro-chemical reactions came into limited employment. Here the appearance of easily crystallizable salts under the microscope was used for diagnostic purposes. This method has been extensively examined of late years and became so overloaded with precautions that its chief asset, that of rapidity and case of employment, has been largely lost. Quite recently colorimetric reactions have been applied to qualitative analysis. These appeared so promising that the present author was encouraged to endeavour to apply them to the examination of minerals.A scheme for the qualitative determination of the commoner elements was published by G. Gutzeit in 1929, which at first sight looked very attractive.
A new apparatus for the determination of carbon dioxide
Authors: Hey Max H. 
Published: December 2006

As most analysts recognize, the method generally used for the determination of carbon dioxide present as carbonate, by decomposition with acid, absorption in soda-lime or soda-asbestos, and weighing as carbon dioxide, is open to several objections; and several suggestions have been made from time to time with the object of avoiding the use of absorption tubes, but none of these have come into general use, generally because of inconvenience in manipulation.The principal objection to the use of absorption tubes (apart from their general inconvenience and the numerous precautions their use entails) lies in the uncertainty of the blank correction; when a blank experiment is performed, under precisely the same conditions as the actual determination, a small gain in weight of the absorption tubes is almost invariably observed, but in a series of several blank experiments, this gain is frequently very variable, and by no means proportional to the volume of air drawn through the absorbers, unless many precautions are observed.
Apophyllite from Traprain Law, East Lothian
Authors: Anderson J. G. C. , Elder S. 
Published: December 2006

Introduction and mode of occurrence.-During a visit in 1929 to the well-known phonolitic laccolith of Traprain Law, East Lothian, beautiful crystals of apophyllite were discovered in drusy cavities. It was found possible to collect numerous specimens which are now in the Hunterian Museum, University of Glasgow (M 5970). There is no previous record from the locality and the following is a brief description of the rock and its associates.Along with the apophyllite occur well-formed icositetrahedra of analcime. A thin section reveals that the apophyllite is of later crystallization than the analcime. The latter mineral lines the walls of the cavities, with which the apophyllite is seldom in contact. Radiating fibres of pectolite are occasionally seen on the surface of the analcime.
Studies on the zeolites. Part IX. Scolecite and metascolecite
Authors: Hey Max H. 
Published: December 2006

Scolecite was recognized as an independent species by A. F. Gehlen and J. N. Fuchs (1813), being one of the species into which they divided, on chemical grounds, the mesotype of R. J . Haüy (1801). Its individuality has rarely been doubted, though occasionally the union of natrolite, mesolite, and scolecite into one isomorphous group has been proposed.Three varieties of scolecite have been described, but all have proved to be other minerals. Thus poonahlite (H. J. Brooke, 1831 ; = mesolite) was long included with scolecite. Lehuntite (T. Thomson, 1836; = natrolite) was classed as a soda-scolecite by A. Kenngott (1850) solely on account of its high water content. And a mineral from Pargas, Finland, was described by N. Nordenskiöld (1821) as anhydrous scolecite (wasserfreies Scolezit); this was copied by W. Phillips (1823) as 'scolecite', and this incorrect copy appears to be the authority for the citation of Pargas as a scolecite locality by Dana and others.
The variable composition of cordierite in the Dartmoor granites
Authors: Brammall A. , Rao B. Rama 
Published: December 2006

The recognition of pronounced varietalism in both the garnet and the basic mica of the Dartmoor granites prompted the authors to inquire whether the cordierite associated with these species was similarly variable in composition.The inquiry was directed in the first instance to possible variation in the optic axial angle 2V, which is determinable with accuracy on the unaltered parts of cordierite in thin rock sections. Determinations made on the sector-twinned cordierites in the garnetiferous granite of Sweltor a gave the following peculiar results, which Mr. Rama Rao verified repeatedly, using a Fedorov microscope in perfect adjustment.
The distribution of gold and silver in the crystalline rocks of the Malvern Hills
Authors: Brammall A. , Dowie D. L. 
Published: December 2006

In re-examining the crystalline rocks of the Malvern Hills, the senior author has had occasion to apply quantitative spectroscopic data for the rarer constituents of hornblendes and micas. The recognition of silver in the spectrograms of biotite led to tentative fire-assays of granitic rocks in bulk-a procedure which revealed the presence also of gold.The assay results for this preliminary suite of granitic types are given below; values less than 5 grains per ton are returned as 'traces':The higher values appear to be related to the reddening of the felspars, which is a widespread 'late' pneumatolytic effect; it is conspicuous in the major granite masses and related pegmatites, but somewhat local and 'arterial' in its distribution over rocks of pre granite age. Among the igneous rocks of post-granite age, the intrusive granophyric quartz-diabase ('Ivy Scar' type) shows only feeble reddening; the newer dolerites are unaffected.
The potash-soda-felspars. I. Thermal stability
Authors: Spencer Edmondson 
Published: December 2006

In a previous paper (24) the writer discussed the relations between the chemical and physical properties of a number of potash-sodafelspars, mainly of the schillerized or perthitic variety, and the effect of high temperatures upon them. The present paper gives the results of further examination of these and of several additional specimens selected to make the range of composition more complete.Twenty-six specimens were selected for this investigation. They include two albites, six microclines, and eighteen felspars which have been grouped as an orthoclase-microperthite series. The confused nomenclature of the alkali-felspars makes a choice of suitable names difficult. Alling's classification (1, pp. 253-254) represents a systematic attempt to overcome this confusion, but it seems doubtful whether some of his arbitrary subdivisions (e.g. ‘anorthoclase potentially eutectoperthite’ and ‘microcline eutectoperthite’) can exist.
An interesting occurrence of lawsonite in glaucophane-bearing rocks from New Caledonia
Authors: Joplin Germaine A. 
Published: December 2006

The writer has recently described a small collection of glaucophane- schists from the Diahot valley and the north-east coast of New Caledonia (Jensen, 1936), and four of these contain lawsonite.Lacroix (1897) has recorded lawsonite from New Caledonia, but the occurrence seems worthy of further mention as in two cases the lawsonite is found to be pseudomorphing plagioclase in doleritic rocks which show a relict ophitic fabric. So far as the writer is aware, such an occurrence of lawsonite pseudomorpbing felspar has not been recorded, though Lacroix figures a glaucophane-schist from Corsica which suggests this structure. The other two lawsonitebearing rocks from New Caledonia seem to have been coarse-grained plutonic rocks and probably never had an ophitic fabric.
Magnesium-zinc-spinels from Ceylon
Authors: Anderson B. W. , Payne C. J. 
Published: December 2006

Although the mineral spinel belongs to an isomorphous group, and in the simple formula MgO.Al2O3 a both Mg and A1 are susceptible to isomorphous replacement, yet in the transparent varieties oI gem quality there is, as a rule, very little deviation from the type composition, and the physical properties are moderately constant. In fact, one may say that the only considerable replacement hitherto recorded in spinels used as gemstones is by ferrous iron in the variety known as ceylonite or pleonaste, which is black and opaque even when 7 or 8 % of FeO is present, the end-member of this series being hercynite, FeO.Al2O3, with 41% ferrous oxide.The purpose of this paper is to draw attention to certain transparent blue spinels from the gem gravels of Ceylon, the physical properties of which differ quite strikingly from those of the normal spinels, from which they are indistinguishable in appearance, magnesium being replaced in this instance not by ferrous iron but by zinc.