bluuebunny/crossref_metadata_2025 huggingface dataset:
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.
Occurrences of zircon in the Dartmoor granite
Authors: Brammall Alfred , Harwood H. F.
Published: December 2006

Thin sections afford a very inadequate basis for the determimation of thc accessory minerals present in the Dartmoor granite, and they are of little or no value for assessing the relative proportions of these minerals. A recognizable cryst'd of zircon, for example, is rarely seen iu thin sections of this granite, and uutil zircons were isolated in quantity from the crushed rock, stream-sands, &c., one type of zircon was not detected.
The dissociation of dolomite
Authors: Garnett Cecil S.
Published: December 2006

That dolomite (CaCO3 . MgCO3) on being heated behaves as though it were a mixture of the two carbonates by dissociating in two distinct stages, appears to be the widely accepted opinion. Thus it is staled (Mem. Geol. Survey, Special Reports on Min. Resources, London, 1920, vol. 16, ‘Refractory Minerals’, p. 102) ‘On calcination, dolomite undergoes a progressive dissociation which may be considered chemically as covering two distinct stages. The first effect of rising temperature is the expulsion of carbon dioxide from the magnesium carbonate contained in the dolomite and the formation of a mixture of magnesium oxide and calcium carbonate, accompanied by a considerable reduction in volume… . Complete calcination results in the expulsion of the remaining carbon dioxide, a still further reduction in volume, and the production of a dense crystalline aggregate of magnesium and calcium oxides.’
The meteoric iron of Karee Kloof, and the meteoric stones of Leeuwfontein and Sinai Peninsula
Authors: Prior G. T.
Published: December 2006

Through the kindness of Mr. F. W. FitzSimons, Director of the Port Elizabeth Museum, South Africa, pieces of this iron were placed at the disposal of the writer for examination and analysis. The original mass, weighing about 203 lb. (92 kg.), was found at Karee Kloof, about nine miles from Hofmeyer, Cape Province, South Africa, and was presented to the Port Elizabeth Musem by Mr. N. H. Ogilvie in 1914. From a cast which was made under the direction of Miss M. Wilman, Director of the McGregor Memorial Musemn, Kimberley, the dimensions of the mass are approximately 43 × 30 × 20 cm. It is very irregularly shaped, is pitted with ‘thumb-marks’, and is cavernous with depressions, one of which on the side shown in Pl. III, fig. 1, has dimensions of about 20 × 15 × 7½ cm.
Some anomalous optical properties of freshly-prepared mixed crystals of the Seignette salts
Authors: Buckley Harold E.
Published: December 2006

The new crystalline compound triphenyl-bismuthine dichloride, described crystallographically by Mr. G. Greenwood (Min. Mag., 1923, vol. 20, p. 123), possesses the remarkable property of exhibiting crossed axial-plane dispersion of the rhombic ‘brookite’ type and circular polarization. For purposes of comparison, the author prepared specimens of the mixed Seiguette salts, which also exhibit crossed axial-plane dispersion together with circular polarization. The Seignette salts, sodium-potassium tartrate and sodium-ammonium tartrato, crystallize each with four molecules of water ill the bisphenoidal class of the rhombic system. They are truly isomorphous and form a continuous series of mixtures. The acute bisectrix for sodium-ammonium tartrate is normal to (001)and for sodium-potassium tartrate normal to (100). For all proportions of mixture containing 5 % and over of sodium-ammonium tartrate, the acute bisectrix is normal to (001).
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.
Allopalladium from British Guiana
Authors: Spencer L. J.
Published: December 2006

At the November (1923) meeting of the Society I gave an account of a new find of euclase of peculiar habit and of native platinum from the gold and diamond washings in British Guiana. The occurrence of platinum being a new record for that country, the announcement was naturally received there with some interest—but also with some scepticism. Mr. J. C. Menzies, by whom the platinum was found, has been accused of ‘salting’ the locality, or, alternatively, doubt has been cast on the correctness of my determination. The euclase aggregates, thought by Mr. Menzies to be fossils, could certainly not have been used by him for ‘salting’; and as the platinum (together with some small, silvery scales of mica) came with these, I have no reason to doubt his bona tides. I am also quite satisfied with the correctness of my determination of the material as platinum, as set out in detail on p. 191 of this volume.
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.
International agreement in mineralogical and crystallographical nomenclature
Authors: Spencer L. J.
Published: December 2006

A Committee on Nomenclature and Classification of Minerals was appointed at the first annual meeting of the Mineralogical Society of America in December 1920, and two of its reports have been recently issued in the ‘American Mineralogist’. Such a committee for standardizing nomenclature is clearly needed, but it must take a far wider view. If the recommendations can be, or are likely to be, adopted only in their country of origin then the result will be still further confusion in the nomenclature of the science. It is especially important in this connexion to bear in mind that science is world-wide, and its language should, as far as possible, be adapted to meet international needs. The tendency to adapt names to particular languages should rather be discouraged.
Albite and other authigenic minerals in limestone from Bengal
Authors: Spencer Edmondson
Published: December 2006

In that part of the Gangpur State immediately to the north of the Bengal-Nagpur Railway, between Biara and Garpos, lies a tract of dolomite- and limestone-bearing country which has been referred, on lithological grounds, to the Cuddapah (? Algoukian or Palaeozoic) formation. From this area, all the dolomite and most of the limestone requirements of the Bengal iron and steel industry are at present derived, and the close proximity of the enormous haematite ore reserves of Singhbhum indicates a still greater economic importance for these materials in the future.
The crystal-structures of the sulphides of mercury
Authors: Buckley H. E. , Vernon W. S.
Published: December 2006

Mercuric sulphide, HgS, occurs in nature as two well-known modifications, cinnabar and metacinnabarite. The latter is some what rare and occurs as black cubic crystals possessing the symmetry of the zinc-bleude, i.e. the ditesseral polar-class. It is considered to be identical with chemically precipitated black mercuric sulphide, the density of both being 7.81. Cinnabar is of more common occurrence and is found as well-defined crystals and in the massive state. The crystals are assigned to the trigonal holoaxial class. The rhombohedral angle is 92°30' r correspouding to an axial ratio c/a of 1.1453. The crystals possess a very good cleavage parallel to the prism (21̄1̄)=(101̄0). The rotation of the plane of polarization, for red light traversing the crystal in a direction parallel to the optic axis, is 315° per millimetre, a value roughly eighteen times that of a similar thickness of quartz.
On some chloritic minerals associated wlth the basaltic Carboniferous rocks of Derbyshire
Authors: Tomkeieff S. I.
Published: December 2006

The occurrence of chloritic minerals as infillings of vesicular cavities in volcanic rocks is very common in rocks of all geological ages. Numerous chlorites have been described and analysed, but their classification and nomenclature are complicated by the fact that, as in the case with other hydrous alumino-silicates such as zeolites and clay minerals, the chloiites present a great variety of chemical compounds, usually of indefinite composition.
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.
The Identity of the Cobija and Lampa meteoric stones
Authors: Mountain E. D.
Published: December 2006

From an examination of thin sections of specimens in the British Museum (Natural History) labelled Cobija and Lampa and also from a consideration of the present distribution of these meteorites in the British Museum and in the Ward-Coonley collection in the Field Museum of Natural History, Chicago, Dr. G. T. Prior thought that there was strong evidence in favour of their identity. In his 'Catalogue of Meteorites' (1923, p. 95) ho states with reference to the Lampa stone: 'Except that it is more oxidized, in characters it is very similar to Cobija, and may be identical with it since the information as to locality was obtained not from H. A. Ward but indirectly from the School of Mines, Santiago.' Dr. Prior subsequently handed me these meteorites for a chemical examination.
Schultenite, a new mineral, from South-West Africa
Authors: Spencer L. J. , Mountain E. D.
Published: December 2006

Baron A. De Schulten, a political refugee from Finland, worked during the latter part of his life in the chemical laboratories of the Sorbonne in Paris. There he prepared in a crystallized form number of minerals and compounds analogous to them. These were determined crystallographlcally and compared in isonlorphous series. For example, having obtained crystals of artificial monetite, CaHPO4, he then proceeded to prepare the corresponding compounds in which strontium, barimn, or lead take the place of calcium, and arsenic the place of phosphorus. In this series he determined the crystallographic constants and optical data for CaHPO4, SrHPO4, BaHPO4, PbHPO4, SrHAsO4, and PbHAsO4. Crystals of CaHAsO4 were also obtained, but they were too small tbr measurement. Any of these compounds might be expected to occur in nature, but hitherto only monetite has been found as a mineral.
X-Ray examination of aramayoite
Authors: Yardley Kathleen
Published: December 2006

An attempt was made to determine the true symmetry of the cleavage flakes of aramayoite by means of the Laue photographic method. Since X-ray diffraction takes place within the crystal, the lack of welldeveloped faces other than main cleavage faces was no disadvantage. One feature, however, which did prove a difficulty, was the pliability of thin clevage flakes referred to by Dr. Spencer. It was essential that the whole of the main cleavage face upon which the X-ray beam was incident should be strictly perpendicular to that beam. In order to ensure this, only those flakes were used which gave a single optical reflection, and two distinct methods of setting were resorted to. In the first case the slit (circular aperture) was used vertically ; the flat end of the slit system was ground truly perpendicular to the slit itself and was thus horizontal.
The temperature-range of formation for tourmaline, rutile, brookite, and anatase in the Dartmoor granite
Authors: Brammall A. , Harwood H. F.
Published: December 2006

The range of temperature within which tourmaline can arise in nature has not hitherto been determined. No synthesis of this mineral is on record, and experimental data are therefore lacking. On the other hand, rutile, brookite, and anatase have all been prepared synthetically, and the experimental data suggest their rutile is formed at the highest temperatures, brookite at temperatures considerably lower, and anatase at a point still lower on the scale. It is generally conceded that for rutile a pyrogenic origin is possible, and that brookite and anatase appear only as secondary minerals. The status of tourmaline as a possible pyrogenic mineral is regarded as doubtful by Clarke, who states that' in igneous rocks tourmaline seems to have been produced by fumarole action, and not as a direct separation from the magma'.
On laurionite and associated minerals from cornwall
Authors: Russell Arthur , Hutchinson A.
Published: December 2006

The two exceedingly interesting specimens which form the subject of the present notes came under my observation in the following manner. In 1905 there was sold by public auction in London an old and very fine collection of minerals, mostly Cornish, which had been formed by John Hawkins, F.R.S. (b. 1758, d. 1841), of Trewithen, Probus, Cornwall; a gentleman well known in his day both as a scientist and traveller. The major part of the collection unfortunately left this country, having been purchased by the dealer F. Krantz of Bonn. A few lots were, however, bought by myself, and one of these contained the first specimen to be here described.
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.
A study of bauxite
Authors: Rao T. V. M.
Published: December 2006

Bauxite is of twofold interest due firstly to its economic importance, and secondly to the scope it affords for scientific investigation. When these two reasons are taken into consideration, one can easily account for the enormous and rapid accumulation of literature concerning this subject. Any attempt to give a detailed account of the literature will only mean unnecessary repetition of what has been already dealt with at great length by several writers, of whom Anderson and Fox may be specially mentioned. The relation between bauxite and laterite is so intimate that a detailed study of the one is impossible without any reference to the other, and as such the description of and frequent reference to the latter should not be considered as any digression from the subject.
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.
The so-called ‘thermokalite’ and the existence of sodium bicarbonate as a mineral
Authors: Bannister F. A.
Published: December 2006

In a brief account of the Johnston-Lavis collection of Vesuvian minerals, now preserved in University College, London, Dr. K. W. Earle mentions ‘a large number of specimens of “Thermokalite”, a new member of the Haloid group, which has, apparently, so far escaped description.’ This previously unpublished name was copied from Dr. Johnston-Lavis's manuscript labels. The late Dr. H. J. Johnston-Lavis (1856-1914) possibly considered that this mineral was the potassium compound corresponding to thermonatrite [Na2CO3.H2O]. A provisional name for an undetermined mineral having, in this way, unfortunately been published, it seemed desirable to clear up the matter. For this purpose Dr. Earle very kindly supplied two good specimens of the mineral for investigation. Access was also given to the note-books kept by Dr. Johnston-Lavis. He had made a separate entry for each specimen and the carbon copies were placed with the specimens. The entry for ‘thermokalite’ reads in every case : ‘Thermokalite (n. sp.) by Tunnel nr. Stufe di Nerone, Baja.’ This locality is situated about nine miles west of Naples in the Phlegrean Fields (Campi Phlegraei).
On the atomic volume relations in certain isomorphous series. III.
Authors: Hallimond A. F.
Published: December 2006

Accurate knowledge of the compressibility of solids was first due in a large measure to the investigations of T. W. Richards, who showed that the pressure-volume curves for sodium and potassium approximate in form to rectangular hyperbolae, that the compressibilities of the free alkali metals are nearly proportional to the atomic volumes, and that the atoms can be treated as filling the available space. Richards then endeavoured to calculate the relative volumes of the combined elements in the alkali halides, assuming that the large contraction which takes place on forming the compound was due to an internal pressure which affected equally the alkali metal and the halogen.
‘Bauxite’ from Kashmir
Authors: Rao T. V. M.
Published: December 2006

Although frequent references have been made during recent years to the ‘bauxite’ deposit of Jammu in Kashmir, no complete account giving its geological relations is yet available. The only published,account is that of Middlemiss, and Fox has also made brief references to it in his recent book on bauxite. Previous work on bauxite by the present writer induced him to examine these rocks, and through the kind intervention of Prof. W. W. Watts a complete set of them was obtained from the authorities in Kashmir. Only the petrological and chemical aspects of these specimens have been dealt with here, and consideration of any possibility of their economic use has been avoided.
On a partially fused quartz-felspar-rock and on glomero-granular texture
Authors: Hawkes Leonard
Published: December 2006

The specimen to be described was found in 1925 by Miss H. K. Cargill and Miss J. A. Ledeboer on a scree slope beneath a gully in the basaltic capping of the Slaufrudal granite-granophyre stock at Kvosafoss, SE. Iceland. Unfortunately the rock was not discovered in situ, but it must belong to the upper part of the stock or a dike apophysis of it. An examination of the rock was begun by Miss Ledeboer, but she was unable to continue the work; I am indebted to her for the photographs of pl. VII, figs. 1 and 2.
The occurrence of a mineral hitherto unrecognized in the phonolites of Dunedin, New Zealand
Authors: Marshall Patrick
Published: December 2006

The phonolites which are found in the volcanic region of Dunedin, New Zealand, are of a varied character. Some of them are of ordinary types, but others are nephelinitoid, and some of them have sodalite in abundance. Besides the phonolites, there are trachydolerites, some of which also contain sodalite as well as nepheline. There is also an abundance of tinguaites, in all of which nepheline is distinct and sometimes sodalite as well. All petrologists who have worked in this region are therefore perfectly familiar with the minerals sodalite and nepheline in many different associations and conditions.
Fülöppite, a new Hungarian mineral of the plagionite-semseyite group
Authors: Finály I. de , Koch Sándor
Published: December 2006

In the Autumn of 1928 Dr. Béla Fülöpp and Mr. G. Kupás sent for examination an unknown mineral, which had been found in no. III level on the main lode of the Kereszthegy mine at Nagybánya, comitat Szatmár [now Baia Mare, Satul-Mare, Romania]. The small crystals show a close resemblance to those of plagionite from Wolfsberg in the Harz Mountains, but the results of our detailed examination prove that we have here a new mineral. For this we propose the name Fülöppite in honour of Dr. B. Fülöpp, an enthusiastic collector of minerals and a generous patron of the Magyar Nemzeti Mfizeum (Hungarian National Museum).
Scawtite, a new mineral from Scawt Hill, Co. Antrim
Authors: Tilley C. E.
Published: December 2006

The mineral now briefly described occurs as a rare constituent of the zone of hybrid rocks formed by assimilation of limestone by the dolerite intrusion at Scawt Hill, Co. Antrim. It is found particularly in intimate association with the melilite-bearing types of this hybrid zone and is a constituent of some of the late-formed vesicles in these rocks. The minerals associated with it in the vesicles are chiefly calcite, thomsonite, and another zeolitic mineral as yet undetermined. These vesicles are most frequently enclosed by a ground rich in melilite, or they may occur within large crystals of melilite. In some cases the mineral forms minute venules cutting through the melilite, suggesting that it is derived in part by attack of residual solutions upon the melilite itself. All the evidence clearly indicates that the mineral is among the latest products of consolidation of the hybrid zone.
Pericline and acline-A twins in the acid plagioclases
Authors: Phillips F. Coles
Published: December 2006

The orientation of the ‘rhombic section’, the composition-plane of the pericline twin, in the plagioclase felspars as an index of the chemical composition of the felspar waJ first utilized by G. yore Rath, who measured the gngle a on the face (010) between the trace of the composition-plane and the edge [010,001]. Duparc and Reinhard, in their comprehensive work on the determination of the plagioclases, quote two series of values for this angle, one due to Wiilfmg and the other to Becke. They comment on the discordance between the two series, most marked at the acid end, and add that they did not then possess suitable material for critical determinations on their own account. Wülfing's values are given in the form of a curve based on data assembled by Schmidt, and those of Becke were first given in a paper on the felspars in crystalline schists.
Studies on the zeolites. Part I. General review
Authors: Hey Max H.
Published: December 2006

The zeolites form a group of minerals of considerable interest by reason of their peculiar properties. In particular, their remarkable continuous dehydration curves, in part reversible, and the ready base-exchange of some members have attracted attention. But in spite of much work, many important characters remain quite uncertain. Many of the zeolites show variations in composition which are not recognized or are incorrectly interpreted by the accepted formulae. Optical investigation has all too rarely been made on analysed material, and little is known of the variation of the optical properties of most members with their composition, and practically nothing of the variations consequent on artificial base-exchange reactions. In spite of much work, conflicting views are still held as to the interpretation of the dehydration results. In some instances even the crystal-system is still uncertain.
An electromagnetic separator for mineral powders
Authors: Hallimond A. F.
Published: December 2006

The separator here described was designed by the author some years ago in order to avoid the tedious process of hand-picking mineral powders in front of an electromagnet. It is a complete machine dealing on a laboratory scale with the less magnetic minerals, such as monazite. For research it is essential that the separation should be clean cut ; in the present case a 90% separation of glauconite from monazite can be made in a single pass, while the removal of more widely differing minerals is complete. The machine must also deal with small samples down to 0.5 gram without loss; this necessitates a small scale and slow feed ; the time required for more bulky samples is consequently rather long, but little or no attention is required during operation. Finally, all the moving parts should be of metal and easily cleaned.
Ephesite (soda-margarite) from the Postmasburg district, South Africa
Authors: Phillips F. Coles
Published: December 2006

The material on which the following description is based was presented by Dr. A. L. Hall to the Department of Mineralogy at Cambridge, and I am greatly indebted to him and to Prof. A. Hutchinson for affording me the opportunity of describing it. The first account of the occurrence was given by Dr. Hall, recording from Aarkop, Magoloring, 'a beautiful delicately rose-coloured mica … in compact dark bluish-grey ore as thick, short, colmnnar aggregates not unlike little books of mica with pseudo-hexagonal outlines and showing the characteristic perfect basal cleavage … the mate: rial was found on the higher slopes defining the west side of Martha's Kloof'. This description was amplified somewhat in a later publication, with the addition of an analysis (see below). As noted therein the mineral also resembles that described by Chudoba as a manganophyllite allied to the phlogopite group, but the fuller description given below reveals important differences.
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.
Ankerites of the Northumberland coal-field
Authors: Hawkes L. , Smythe J. A.
Published: December 2006

The first recognition of ankerite as a British mineral seems to have been made a little over fifty years ago by M. F. Heddle, who described and analysed a sample from the Ting of Norwick, Unst. The occurrence of the mineral in veins in the Carboniferous Limestone of Lilleshall, Shropshire, was recorded by C. J. Woodward, who gives analyses of two specimens. T. Crook noted the frequent occurrence of the mineral in British coal-fields and described specimens, with two analyses, from Lancashire, Yorkshire, Nottinghamshire, Leicestershire, and South Wales. F. S. Sinnatt and his collaborators, in their work on the mineral constituents of coal, devote a good deal of attention to the 'white partings' or ankerites, of which, as they say, 'no study has appeared in the literature'.
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.
Notes on the occurrence of fluorite in Aberdeenshire and Banffshire
Authors: Russell Arthur
Published: December 2006

Fluorite is by no means a common mineral in Scotland, and Scottish specimens, with the exception of those from Craigmuschat quarry, Gourock, Renfrewshire, arc very rarely to be seen in collections. In the following notes an account is given of some of the more remarkable occurrences visited by the writer in the summer of 1934. Others recorded by M. F. Heddle were also visited and are mentioned, although they no longer yield specimens.
Ettringite from Scawt Hill, Co. Antrim
Authors: Bannister F. A.
Published: December 2006

Ettringite was the name given by J. Lehmann in 1874 to minute, transparent, acicular crystals lining the cavities of metamorphosed limestone-inclusions in leucite-nepheline-tephrite from the Ettringer-Bellerberg, near the village of Ettringen (between Mayen and the Laacher See), Rhineland. Lehmann detached sufficient needles from the limestone for chemical analysis, and found that they were not gypsum, as formerly supposed, but a hydrated calcium sulphoaluminate.
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.
‘Iron-rhodonite’ (from slag) and pyroxmangite and their relation to rhodonite
Authors: Perutz Max
Published: December 2006

The pyroxmangite and rhodonite, here examined by X-ray methods, are from the Lewisian schists at Glen Beag, in the Glenelg district, Inverness-shire. The material was exhibited by Prof. C. E. Tilley at the meeting of the Society on November 5, 1936, and it has since been described by him. The specimen of ‘iron-rhodonite’ was from the iron slag described by Whiteley and Hallimond, and is no. 7a in their table of analyses.

The unit cell of the ‘iron-rhodonite’ was determined by means of the Weissenberg goniometer and the data obtained are compared in table I with Gossner and Brückl's determination for rhodonite. The unit cell of pyroxmangite was determined by taking a Weissenberg photograph about the c-axis and oscillation photographs about the a- and b-axes.
A universal ore-polishing machine (With Plate XXI.)
Authors: Phillips F. C.
Published: December 2006

Available methods of grinding and polishing ore-minerals, in preparation for their examination with the ore-microscope in reflected light, fall into two categories. The more usual procedure, adapted from the corresponding methods in metallography, involves the use of high-speed laps faced with soft materials and supplied with relatively large quantities of abrasive mixed with water. The advantages of this method are its rapidity (about ten minutes will usually suffice for the whole series of processes), the possibility of using unmounted chips, and the simplicity of the necessary equipment. Amongst its chief disadvantages are the high relief developed between hard and soft minerals in the same specimen and the dirtiness of the process owing to the large amounts of wet sludge produced.
A new micro-pyknometric method for the specific gravity of heavy solids; with a note on the accuracy of specific gravity determinations
Authors: Bannister F. A. , Hey Max H.
Published: December 2006

The determination of the specific gravity of a solid which is only available in small quantity has always been a difficult problem in cases where the suspension method fails, either because the solid is too dense, or because it dissolves in or reacts with the heavy liquids available. It is hoped that the following method will be found a useful addition to the numerous methods which have been proposed from time to time to meet such cases. References to most of these methods are given at the end of the paper. Neither the new method nor any one of the older ones is universally applicable, and the best method for any particular case will depend on many circumstances.
The potash-soda-felspars. II. Some applications to petrogenesis
Authors: Spencer Edmondson
Published: December 2006

In the first part of this paper (33) the effects of heat on the potash-soda-felspars were considered, and a possible explanation in terms of atomic rearrangement was proposed. In this part the experiments, and deductions from them, will be applied to some questions of petrogenesis and differentiation, particularly in connexion with the granites and granite-pegmatites.
The identity of zinckenite and keeleyite
Authors: Vaux George , Bannister F. A.
Published: December 2006

Zinckenite was first described in 1826 by G. Rose, who determined it to be an orthorhombic mineral. The crystals were thought to be seldom single, but to occur in nearly hexagonal forms as a result of twinning in some fashion similar to that found in aragonite. The presence of longitudinal striations on the lateral faces was taken as further evidence that the crystals were twinned. The composition was given by H. Rose as PbSb2S4or PbS.Sb2S3. The original specimens which were described came from the antimony mine of Woffsberg in the Harz.

In 1922 S. G. Gordon described a new lead sulfantimonite from Oruro, Bolivia, which he named keeleyite. This mineral he presumed to he orthorhombic, although no measurable crystals were found, and the formula was given as Pb2Sb6S11or 2PbS.3Sb2S3.
Russellite, a new British mineral
Authors: Hey Max H. , Bannister F. A. , Russell Arthur
Published: December 2006

In May, 1936, a quantity of pale yellow, rounded fragments, averaging 7 mm. across, was submitted to us by Mr. Arthur Russell for examination, with the information that the material came from the Castle-an-Dinas wolfram mine, and contained bismuth and tungsten. Chemical and spectroscopic examination showed that, besides bismuth and tungsten, the mineral contained only traces of silicon, arsenic, and iron. A sample of the same material had also been given to the British Museum by Mr. E. H. Davison in 1934 and registered provisionally as bismuth tungstate. This, however, would not have provided sufficient of the yellow mineral for chemical analysis. We are also indebted to Mr. Davison for a further generous supply of yellow pellets picked from the wolfram concentrates received since tile present work was begun. The mineral has all the attributes of an alteration product probably of native bismuth. It is fine-grained and compact, with hardness 3½, and on fracture it gives a clay-like odour. Some of the pellets show traces of a micaeeous mineral and quite frequently enclose native bismuth, wolframite, and bismuthinite. Mr. Russell has picked out from tihe material he had collected a few green pellets and some showing both the yellow and the green mineral. Spectrographs of the two are identical, but an X-ray powder photograph of the green mineral is quite distinct from that of tile yellow mineral.