bluuebunny/crossref_metadata_2025 huggingface dataset:
Note on the occurrence of anatase in some fireclay deposits
Authors: Brindley G. W. , Robinson Keith
Published: December 2006

In X-ray studies of fireclays we have frequently observed the presence of anatase to the extent of 1 or 2% with little or no rutile, and no brookite. Chemical analyses of these clays usually record 1–2% of TiO2 and occasionally more (Ennos and Scott, 1924). The mineralogical form of the TiO2 is usually not stated, but a number of references to the observance of rutile needles give the impression that rutile is the form in which titania occurs in these deposits. Our own observations based on X-ray powder photographs lead us to conclude that anatase is commonly present and that rutile is either absent or present in smaller quantities. We have not detected brookite.
Catalogue of topographical mineralogies and regional bibliographies
Authors: Spencer L. J.
Published: December 2006

Some time previous to 1894 the late Sir Henry A. Miers, then an assistant in the Mineral Department of the British Museum, collected together all the books in the departmental library which gave a systematic account of the minerals of particular regions. Since then the set has been considerably added to, and it now forms a very valuable, probably unique, series. Its primary use was for the more precise labelling of the localities of specimens in the collection; and as it grew it became more and more useful for answering inquiries on the minerals of particular districts. In 1900 I started a note-book for collecting further references from the literature. This was added to by the late Mr. George Savigar, clerk in charge of the departmental library; and later Miss J. M. Sweet compiled a card-index of all the entries. The department also has card-indexes of the localities of mineral and rock specimens in the collection.
A note on the thermal decomposition of chrysotile
Authors: Hey M. H. , Bannister F. A.
Published: December 2006

During the course of a detailed X-ray study of chrysotile, antigorite, and gümbelite by E. Aruja we were asked to confirm some interesting results he had obtained on heating chrysotile to various temperatures. This we were able to do and also to provide additional data which were recently referred to in a paper by A. Hargreaves and W. H. Taylor. Although we have not succeeded in providing a completely satisfactory explanation of the optical changes observed on heating chrysotile our observations for a limited range of temperatures in the neighbourhood of 1000° C. are here recorded.
Dickite and collophane in the Magnesian Limestone of Durham
Authors: Dunham K. C. , Claringbull G. F. , Bannister F. A.
Published: December 2006

In the course of examining the cores of a boring for water at Hesleden Dene, near Castle Eden, Co. Durham (no. 2 borehole), Mr. A. Fowler noticed a cream-coloured flaky mineral of talcose aspect coating joints in the Magnesian Limestone (Permian), at depths below surface of 246 to 250 feet. The rock at these depths is an impure dolomite mudstone (Geological Survey Slice, no. E. 21304) resembling the Marl Slate, and carrying ostracods, foraminifera, and sponge spicules. Investigation of the coatings in specimens sent in by Mr. Fowler and by Mr. W. Anderson has shown that the flaky mineral is dickite, and that it is associated with fluorite, baryte, galena, zinc-blende, pyrite, and collophane. Dr. J. Phemister had previously concluded on optical evidence that dickite might be present among the minerals of metalliferous affinities discovered in the Magnesium Limestone by Mr. Fowler.
Ganophyllite from the Benallt Mine, Rhiw, Carnarvonshire
Authors: Smith W. Campbell , Bannister F. A.
Published: December 2006

Ganophyllite was first detected in the Benallt mine as small fibrous patches varying in colour from pale pink to brown, in the thin vein cutting ore in the Ty Canol incline from which the manganese-rich chlorite, pennantite, was described. These were identified by X-ray photographs. It had previously been found at the neighbouring Nant mine by Sir Arthur Russell in 1911.
The identification of minerals in boiler deposits. Examples of hydrothermal synthesis in boilers
Authors: Clark L. M.
Published: December 2006

Many examples of the hydrothermal synthesis of minerals are scattered throughout mineralogical literature. The present paper has been written to bring to the attention of mineralogists the fact that such hydrothermal syntheses are occurring continually in industrial boilers, particularly when control of water softening procedure is not completely efficient.
The application of phase-contrast microscopy to mineralogy and petrology
Authors: Smithson Frank
Published: December 2006

Phase-contrast methods in microscopy appear to have been developed mainly with the intention of applying them to biological subjects, and their application to the examination of mineral substances has received only slight attention. Thin sections of rocks viewed under a phase-contrast microscope have a fascinatingly strange appearance and it does not take long to realize that some features are shown up more clearly and others less clearly than when viewed under an ordinary or a polarizing microscope. A considerable amount of work may be necessary before it is possible to assess the value of the new instrument for petrological purposes or to interpret all the phenomena observed by its aid. Nevertheless, it seems fitting to set out the following short account as a contribution towards this knowledge.
X-ray studies of halloysite and metahalloysite
Authors: Brindley G. W. , Robinson Keith
Published: December 2006

Metahalloysite is one of the kaolin group of minerals with a composition approximating to the formuia Al2O3.2SiO2.2H2O, and its structure is generally considered to be built of composite layers of atoms of the kind found in other minerals of this group. It differs from them most strikingly in that it can be produced by the dehydration of the hydrated mineral halloysite, which has the approximate composition Al2O3.2SiO2.4H2O. Both minerals give comparatively poor X-ray diagranm showing relatively few lines attd bands. The lines correspond to reflections from a basal spacing of about 7·2 Å. in metahalloysite and 10·1 Å. in halloysite.
X-ray studies of halloysite and metahalloysite
Authors: Brindley G. W. , Goodyear J.
Published: December 2006

The experiments described below on the dehydration of halloysite were largely carried out in the laboratoire Central des Services Chimiques de l'État, Paris, where we enjoyed not only the excellent facilities of the laboratory but also the advice of Monsieur J. Méring and Mile R. Glaser who had made similar studies of montmorillonite. The use of a Guinier-type focusing camera with strictly monochromatic radiation was especially useful. These experiments were undertaken because little was known about the dehydration process beyond the recognition that it occurs very readily in dry atmospheres and at low temperatures. The main experimental difficulty lies in differentiating between water adsorbed oil external surfaces of the clay particles (adsorbed water) and water internally absorbed between the kaolin layers (interlayer water).
X-ray studies of halloysite and metahalloysite
Authors: Brindley G. W. , Robinson Keith , Goodyear J.
Published: December 2006

This paper concludes the account of our experiments on halloysite and is to be read in conjunction with the two previous parts, to which frequent reference will be made.

The effect of heat-treatment on metahalloysite was examined with the primary object of ascertaining if a recrystallization or ‘kaolinization’ of metahalloysite could be achieved.
A refractive index comparator for the microscope
Authors: Dollar A. T. J.
Published: December 2006

This stage-attachment simplifies microscopic comparison of refractive indices of small transparent grains by the immersion-liquid methods of O. Maschke, Schroeder van der Kolk, and other workers. It was designed in 1938 for use in mineralogy and petrology, but has applications in several branches of pure and applied chemistry, patticularly for determining the relative purities of numerous raw materials and refined products of the chemical industry and in checking the constituents of glasses, slags, refractories, and cements. It can be used with advantage, also, in the optical study of soils.
The densest and the least dense packings of equal spheres
Authors: Melmore Sidney
Published: December 2006

Of the results which have so far been achieved by study of the packing of equal spheres one of the most remarkable, both by reason of its simplicity and of its fundamental importance, was that announced by Barlow in 1883. He called attention to the fact that equal spheres can be most densely packed in two ways, one possessing cubic symmetry and the other hexagonal (fig. 1).

Already in 1862 Tait had investigated the piling of marbles of equal size and had noticed that ‘there are two obvious ways of constructing the layers, and two of applying layer to layer’: nevertheless his two densest arrangements are in fact identical. He saw that the cubic structure could be begun either upon a square base or a triangular base but failed to perceive the possibility of the hexagonal arrangement.
An optical and X-ray examination of the basic-slag mineral silicocarnotite
Authors: Riley D. P. , Segnit E. R.
Published: December 2006

Blue pleochroic crystals obtained from basic slag were first described by Carnot and Richard. They published a chemical analysis, some of the optical properties, and a brief description of the forms they observed. The crystals were stated to be orthorhombic, with a composition of 5CaO.P205.SiO2. Several authors later described similar crystals. None, however, gave a thorough account of the optical properties. These various papers were summarized and discussed by Kroll, who accepted Carnot's formula, but concluded, from Bücking and Linck's examination, that the material was monoclinic. Kroll applied the rather unfortunate term ‘silico-carnotite’ to these crystals.

The present work shows that silicocarnotite occurs in only one modification–orthorhombic. The crystals drawn by Bricking and Linck and described as monoclinic are, in fact, identical with our orthorhombie crystals.
Clinozoisite from Camaderry Mountain, Co. Wicklow
Authors: Johnston R. W.
Published: December 2006

The clinozoisite to be described is found in veins traversing a metamorphosed basic intrusion exposed at the top of Camaderry Mountain, Glendalough, Co. Wicklow. This intrusion is a small boss of Lower Palaeozoic age which has been metamorphosed both by earth movement and by the intrusion of the Leinster granite. The rock exposed is now an amphibolite (fig. 1) within which are found the veins carrying clinozoisite with albite and a little prehnite, sphene, and tremolite. These veins, which are up to an inch in width, were probably introduced during the late stages of the basic intrusion as veins of lime-rich plagioclase.

Preliminary examination under the microscope shows that the clinozoisite is well crystallized, fresh, and free from inclusions. The colour in the hand-specimen is grey-white; in thin section it is colourless. Individual crystals are found up to 5 mm. in length. Twinning and intricate zoning are common.
The Wherry mine, Penzance, its history and its mineral productions
Authors: Russell Arthur
Published: December 2006

If the visitor standing at Wherry Town on the south-western end of the esplanade at Penzance looks seaward he will observe at low tide at some distance from the shore a low scaweed-clothed rocky shoal (fig. 1), and from his now very conventional surroundings it is difficult to realize that upon this shoal, always surrounded by water, there existed many years ago a rich tin mine, unique in the boldness of its conception, romantic in the extreme in its situation and execution, and withal the effort of a poor working miner.

Very fortunately in the year 1790, during the hey-day of its career, this remarkable mine was examined by a very competent observer in the person of John Hawkins (1761 ?-1841), F.R.S., of Trewithen, Cornwall, and Bignor Park, Sussex, and it is to him that we owe most of the details concerning its mode of working, &c. The Wherry mine and its history have always fascinated me, as they must have many others, and in re-telling the old story I have endeavoured to collect all the known facts, both as to the mine itself, its mode of working, and its mineral productions, and in so doing pay tribute to its gallant and resourceful originator Thomas Curtis.
Goethe's interest in British mineralogy
Authors: Hennig John
Published: December 2006

Johann Wolfgang von Goetiie (1749-1832), the bicentenary of whose birth at Frankfurt-on-Main will be commemorated on August 28, 1949, gave us extensive accounts of the development of his studies in optics, botany, and meteorology; with regard to the history of his studies in mineralogy and geology, his most concise statement is his essay ‘Geology, in particular that of Bohemia’. This essay, written in 1817, starts with three quotations. The first is in English:

What is the inference ? Only this, that geology partakes of the uncertainty which pervades every other department of science.

The source of this quotation still remains to be discovered. At the end of this essay, Goethe said that he was:

fortunate in obtaining a series of minerals from all the principal countries. Herr Mawe, the mineral merchant in London, provided me with a most satisfactory collection from Cornwall, and to Herr Ritter v. Giesecke I am indebted for an important addition to my collection of English stream tin and Malacca tin. All these materials have now been well arranged in my collection, but my plan to write something conclusive on this subject could not be carried out, as so many other things I should have liked to do in the scientific field.
The occurrence of iron-cordierite in blast-furnace linings
Authors: Richardson H. M. , Rigby G. R.
Published: December 2006

In an earlier paper the authors described the occurrence of artificial kalsilite in the hearth of no. 3 blast-furnace of the Kettering Iron Company. That paper contained a detailed description of the furnace campaign together with the peculiar conditions observed in the excavated hearth which was found to exhibit zoning in a vertical direction. The third zone containing kalsilitc was described in detail, but the only reference to the second zone stated that it was 2 inches deep (fig. 2, p. 77, this vol.) and consisted of a black glassy slag containing numerous crystals of cordierite (p. 78). The detailed examination of this zone now forms the basis of the present paper.
The petrology of the evaporites of the Eskdale no. 2 boring, east Yorkshire. Part I. The lower evaporite bed
Authors: Stewart F. H.
Published: December 2006

In 1938–39 the D'Arcy Exploration Company, Limited, sank a borehole (Eskdale well no. 2) to a depth of 5040 feet near Aislaby, Eskdale, Yorkshire, to test the oil or gas possibilities in the Permian Magnesian Limestone. As the well was some distance from any previous boring through the Permian salt series, the Company undertook to carry out continuous coring through this series in the public interest. The boring passed through Lias, Rhaetic, and Trias, and finished in the Permian Lower Magnesian Limestone. The geological results of this boring have been discussed by Lees and Taitt (1945), and fig. 1 has been reproduced from their paper. It can be seen that three evaporite beds were passed through; two in the Upper Permian salt zone, and one in the Middle Permian.
The decomposition of biotite in the soil
Authors: Walker G. F.
Published: December 2006

A noticeable feature of many of the soils of north-east Scotland is the presence in them of glistening yellow flakes of decomposed biotite. The light-reflecting property of this material catches the eye even though the flakes themselves are often of very small size.

An analogous process to the breakdown of biotite as reported below occurs in the soil-clays of the area, and the present study was undertaken primarily in order to throw light on the mineralogical nature of the clay fractions of the soils, since the large amounts of anmrphous material associated with the soil-clay minerals renders less satisfactory the direct approach. The mineralogy of the soil-clays will be dealt with in a separate communication.
Illite occurring in decomposed granite at Ballater, Aberdeenshire
Authors: Mackenzie R. C. , Walker G. F. , Hart R.
Published: December 2006

During soil survey in the Deeside district of Aberdeenshire, a light greenish-yellow clay-like material was observed penetrating and coating the altered rock along a vein in a granite outcrop freshly exposed in road-widening operations one mile north-east of Ballater. The material occurs in a crush-band in the rock, and the alteration is apparently due to the action of water, but since the band was still highly altered at the base of the exposure (about 25 feet from the surface) it is not certain from the field relationships whether the water was of hydrothermal origin or whether it percolated from the surface.
The surface structure of crystals
Authors: Seager A. F.
Published: December 2006

C . W. Bunn and H. Emmett have observed the spreading, of multi-molecular layers on growing crystals of artificial compounds, and have suggested that deposition takes place on the high-index surfaces at the edges of the layers. Their work led the author to examine crystals of several mineral species for evidence of the mechanism of growth, and this account is the result of a preliminary survey of the growth structures found.

So many growth structures could be seen with the naked eye or with a hand-lens that it was decided to use low magnifications in order that comparatively large areas of the crystal faces could be examined and photographed at one time. A metallurgical microscope with a prism reflector and 1-inch objective was used for the observations and most of the photography. This work is qualitative rather than quantitative, but it is intended to carry out a quantitative examination of the same specimens later.
Latiumite (sulphatic potassium-calcium-aluminium silicate), a new mineral from Albano, Latium, Italy
Authors: Tilley C. E. , Henry N. F. M.
Published: December 2006

The ejected blocks found in the 'peperino' of the Alban Hills have long attracted the attention of mineralogists on account of their variety in content of well-crystallized minerals. It may be recalled that this Roman region provides the earliest and finest examples of the white octahedral haiiyne, at first referred to a separate species (berzeline), and that this mineral with leueite, yellow garnet, wollastonite, green clino-pyroxene, and melilite form characteristic assemblages in the tufts from Albano, Frascati, and other places.
Kalsilite in venanzite from San Venanzo, Umbria, Italy
Authors: Bannister F. A. , Sahama TH. G. , Wuk H. B.
Published: December 2006

Shortly after the discovery of the mineral kalsilite, the pure potash analogue to nepheline, as a natural mineral occurring in some volcanic ]avas of SW. Uganda by Bannister and Hey, Professor Arthur Holmes suggested that the ncpheline-looking ruineral occurring in a very potash-rich lava at San Venanzo, Umbria, Italy, also might be kalsilitc. His suggestion was based on the high potash : soda ratio of the bulk rock and on the optical properties of the mineral. No X-ray evidence or chemical analysis on the supposed kalsilite has been presented so far.
An improved polarizing microscope. V. The ore-microscope
Authors: Hallimond A. F. , Wilfred Taylor E.
Published: December 2006

Examination in reflected polarized light is now widely used in metallography as well as for mineral sections. The recent introduction of graded diamond abrasives has overcome most of the difficulties in polishing that have previously hindered the widespread use of this important method.

The present instrument (fig. 1) has been designed to give the best available control over the conditions of illumination and extinction, and to provide for the complete analysis of the reflected elliptically-polarized beam. A robust stand of normal grade suitable for general research purposes and works control is provided with a stage rack, reflector unit, and the usual polarizing equipment. It may be adapted for transmitted light by the addition of the detachable substage shown on the right of the figure.
The space-group and cell-dimensions of rankinite
Authors: Moody K. M.
Published: December 2006

Tricalcium disilicate, Ca3Si2O7, which was first described by Shepherd and Rankin, has been found in certain types of slag, and recently as a natural mineral at Scawt Hill, County Antrim, to which Tilley applied the name rankinite. The present work was undertaken after it was discovered that rankinite is formed when afwillite is heated to about 1000°C.
Cheralite, a new mineral of the monazite group
Authors: Bowie S. H. U. , Horne J. E. T.
Published: December 2006

A Green mineral akin to monazite, derived from the State of Travancore in southern India, was investigated chemically during the first world war by the Imperial Institute, London, and was found to be exceptionally rich in thorium and uranium. No description of this unusual 'monazite' has hitherto been published.

The high content of radioactive elements in this mineral led the State Geologist, Mr. Venkitarama Mahadevan, to have a deposit opened up in 1945, in readiness for an assessment of the radioactive mineral resources of Travancore. At the invitation of the former Dewan, Sir C. P. Ramaswami Aiyar, K.C.S.I., K.C.I.E., this assessment was carried out by Dr. C. F. Davidson early in 1946.
A hydrous mica from Yorkshire fireclay
Authors: Carr K. , Grimshaw R. W. , Roberts A. L.
Published: December 2006

Recent investigations into the mineralogical constitution of fireclays have revealed the presence of a micaceous mineral in all samples examined. Naturally-occurring clays may contain up to 30 % of this type of mineral, and exceptional concentrations have been found in the Yorkshire area. Tests on the purified mineral from this source have proved it to be a hydrous mica of an unusually large grain,size.
The relation between area and volume in micrometric analysis
Authors: Chayes F.
Published: December 2006

In a recent note in this Magazine, Dr. R. B. Elliott points out that inclined contacts of grains of considerably different index may bias the result of a micrometric analysis. That there may be some bias of this sort is hardly to be doubted, though I am inclined to feel that he greatly overestimates its importance. His demonstration, however, involves a fallacy so long and widely held as to be worth refuting.
X-ray investigation of hillebrandite
Authors: Heller L.
Published: December 2006

Hillebrandite was first characterized by Wright as a white, fibrous mineral with the composition 2CaO.SiO2.H2O, optical properties αNa 1·605±0.005, γNa 1·612±0.003, moderately weak birefringence, parallel extinction, optic axial angle 2E between 60 and 80° and density 2.692. X-ray powder data were first published by Vigfusson, but these have not been substantiated by later investigators (Clark and Bunn, McMurdie and Flint, and Heller and Taylor). Synthetic dicalcium silicate β-hydrate has been found to resemble hillebrandite closely.
Some data on synthetic aluminous and other pyroxenes
Authors: Segnit E. R.
Published: December 2006

Although detailed experimental investigations have been carried out on the lime, magnesia, and ferrous pyroxenes, relatively little attention has been devoted to synthetic studies of the group involving replacements by ions of higher valencies. In the present study, determinations have been carried out on the limits of solid solution of alumina in pyroxenes in the system CaSiO3-MgSiO3-A12O3. Determinations of the solubility of ferric oxide and titania in diopside were also made.

Pure calcium carbonate, magnesia, silica (crushed and washed rockcrystal), alumina, ferric oxide, and titania were used for the preparation of the mixtures. The constituents in their requisite proportions were fused together four or five times with intervening crushing of the quenched glass. The product was an homogeneous glass free from crystalline material.
An investigation of high-temperature optics in some naturally occurring plagioclases
Authors: Bradley Olive
Published: December 2006

For several years now it. has been generally appreciated that plagioclase felspar formed at high temperature differs optically from that formed at lower temperatures. Much of the evidence for this has been provided by the Austrian workers, notably Köhler (1-3), Scholler (4), and Tertsch (5-7), who have prepared revised curves to supplement the universal-stage stereograms of Reichert (which are for use with lowtemperature material). There are a number of interesting petrological points which have not yet been fully investigated. Much work has been done on synthetic material, and it is not clear to what extent the hightemperature forms occur naturally. There may be two distinct and separate types of plagioclase structure, or the two forms may grade into one another. It may be possible to explain the optical anomalies as an order-disorder phenomenon; a more disordered state has been 'frozenin' in those felspars which ha~e formed a.t a high temperature and cooled rapidly.
A large mineralized cavity in a tholeiite dike in Northumberland
Authors: Randall B. A. O.
Published: December 2006

Towards the end of 1952 mining operations at West Sleekburn colliery, Bedlington, Northumberland, involved the driving of a drift through a 'whin' dike. In the process of doing so an unusual, large cavity was penetrated. When the cavity was first entered, by the manager and under-manager, it was found to be water-free but full of 'gas', which rendered them almost unconscious. Their exploration was therefore delayed until the gas was removed by pumping. Unfortunately no sample of the gas was collected, but it is thought to have been 'fire damp'. After examination the cavity repeatedly filled with gas, leading to a suspicion of a hidden extension to the cavity, under the roadway.
A rapid method for the preparation of thin rock-sections
Authors: Rowland E. O.
Published: December 2006

The basic technique for preparing micro-thin rock-sections has altered little since this method of studying rocks was first accepted. Abrasive powders were, and still are, used either on glass or metal plates, the grinding being done entirely by hand. At the present time carborundum is almost universally used as the abrasive. The technique has been speeded up somewhat by the use of horizontal metal laps, and in more recent years the introduction of high-speed diamond-cutting and lapping apparatus has considerably reduced the time involved in making a thin rock-section. But even with this apparatus the process is still long and laborious, and, even more important, the operator must have considerable skill and experience in keeping the specimen whole and of uniform thickness throughout the entire operation.
The hydrated calcium silicates riversideite, tobermorite, and plombierite
Authors: McConnell J. D. C.
Published: December 2006

In a recent paper Taylor has shown that three distinct hydration levels exist within the ‘calcium silicate hydrate (l)’ group of artificial preparations (Taylor, 1953a, p. 168). The individual hydrates may be distinguished from the position of the 002 reflection in X-ray powder photographs. The d spacings corresponding to the three hydrates of this group examined during the present investigation are 14.6, 11.3, and 9.6 Å. These hydrates have H2O : SiO2 molar ratios of approximately 2.0, 1.0, and 0.5 respectively.

A recent examination of the minerals crestmoreite and riversideite (Taylor, 1953b) has shown that both these minerals are intimate inter-growths of members of the above hydrate series with the mineral wilkeite. Both the artificial preparations and the crestmoreite-riversideite intergrowths have failed to provide material suitable for detailed optical study.
Spectrographic and X-ray data on some fluorites from the Transvaal, South Africa
Authors: Steyn J. G. D.
Published: December 2006

The fluorites of the Transvaal occur in different rock-types, viz in the dolomite of the Transvaal System, in acidic rocks (red granite and granophyre of the Bushveld igneous complex and Rooiberg felsites), and in alkalic rocks. The purpose of this study was to determine:

(1) What minor elements are present in selected fluorites.

(2) What the effect of these elements is on the respective cube-edges.

(3) Whether these elements have any geological significance.

Fluorite displays a wide range of colour; both colourless and distinctly coloured specimens were examined. Differently coloured varieties could in some instances be taken from the same sample. The choice of coloured varieties in the different rock-types was nevertheless limited. Only light-coloured fluorites occur in the dolomite, whereas the alkalic rocks yielded only very dark purple specimens.
Bassetite and uranospathite
Authors: Frondel Clifford
Published: December 2006

Bassetite and uranospathite Were described as new uranium minerals from Cornwall in 1915 by A. F. Hallimond, to whose paper reference should be made to supplement the descriptions given here. The position of both minerals as relatives of autunite was recognized by Hallimond. Unfortunately, chemical analyses could not be obtained and the composition of these minerals has remained uncertain. No further information has been published about uranospathite. In 1940 Meixner reported that microchemical tests of an apparently authentic specimen of bassetite from Cornwall indicated that the mineral was a hydrated iron uranyl phosphate.
Zoned Plagioclases in Layered Gabbros of the Skaergaard Intrusion, East Greenland
Authors: Carr J. M.
Published: December 2006

A limited amount of careful optical work has been carried out on X three analysed felspars of gabbros belonging to the main layered series of the Skaergaard intrusion, east Greenland (Wager and Deer, 1939). The work was begun with the intention of providing precise optical data to be used in further defining the relationship between composition and optics. The primary precipitate felspar crystals, hitherto thought to be devoid of zoning, were found, however, to possess a zoning which prevents the data being used in this way.
Veatchite from the Permian evaporites of Yorkshire
Authors: Stewart F. H. , Chalmers R. A. , Phillips R.
Published: December 2006

Some years ago a few small grains of an unknown mineral were separated by F. H. Stewart from well cuttings from the Permian lower evaporite bed of the Eskdale no. 2 borehole, sunk by the D'Arcy Exploration Company near Aislaby, north Yorkshire. The mineral (not then identified) was mentioned in an account of the mineralogy of this evaporite bed (Stewart, 1949, p. 626). Flame tests suggested that boron and strontium were present, and this was confirmed by Dr. R. L. Mitchell of the Macaulay Institute for Soil Research in Aberdeen, who, by spectrographic work, found that these were the main constituents, and that very much smaller quantities of Ca, Mg, Ba, Na, and K were present.
Two arfvedsonitic rhyolite intrusions from Cloghaneely, Co. Donegal
Authors: Whitten E. H. Timothy
Published: December 2006

Many of the Dalradian and 'Moine' rocks of Donegal, and the Caledonian granites associated with them, have been shown to bear structural and petrographic resemblance to the rocks of similar age in Scotland. In Scotland riebeckite-bearing minor intrusions occur at many localities and include Ordovician, Caledonian, Carboniferous, and Tertiary intrusions. There appears to be no record of analogous rocks containing sodic amphiboles occurring in situ in NW. Ireland. The purpose of this paper is to record the existence of two small intrusions of such rocks in western Cloghaneely, Co. Donegal.
Ferriferous orthoclase from Madagascar
Authors: Coombs D. S.
Published: December 2006

In 1916 Kôzu recorded the fact that a specimen of yellow Madagascar orthoclase, subsequently shown by Seto (1923) to contain 2-93% Fe203, had an optic axial angle of 20° 17' (NaD light) with the optic axial plane parallel to (010). This observation is in apparent conflict with the useful curves relating 2V to composition for alkali-felspars compiled by Dr. O. F. Turtle (1951, 1952). These curves were designed to show how the felspars fall into several more or less distinct series, rather than as an aid to the precise determination of composition, which in fact must be decided by other means. The possibility of transitional forms between the series was clearly recognized (e.g. 1952, p. 565).
The structures of the plagioclase felspars. V. The heat-treatment of lime-rich plagioclases
Authors: Gay P.
Published: December 2006

This work has been primarily concerned with plagioclase felspars within the composition range Ab30An70 to Ab0An100, i.e. felspars with the anorthite-type structure. Some results for less basic specimens will be quoted where appropriate ; a fuller description of the effects of heat-treatments on intermediate plagioclase felspars will be published later.
Truscottite
Authors: Mackay A. L. , Taylor H. F. W.
Published: December 2006

The mineral truscottite was discovered at the Lebong Donok mine, Benkulen, Sumatra, by Hövig in 1914. He considered it to be a hydrated calcium silicate of composition CaO.2SiO2.1/2H2O. Later work by Grutterink suggested a different formula, 2(Ca,Mg)O.3SiO2.2H2O, the water content being reduced to 1-3 molecules after drying at 120°. Grutterink noted that the composition, general character, and optical properties indicated a similarity to gyrolite. Flint, McMurdie, and Wells concluded from X-ray powder photographs that the two species were identical, although they detected quartz as an impurity in the truscottite examined. All known specimens of truscottite come from the original locality, and no further investigations have been reported.
An accessory to the polarizing microscope for the optical examination of crystals
Authors: Vincent H. C. G.
Published: December 2006

Qualitative studies of the optical properties of crystals under the polarizing microscope and refractive index measurements by immersion methods are made on slides placed upon the microscope stage. These procedures have the disadvantage that the crystals have a fixed orientation. Quantitative properties, such as optic axial angles, are measured on an accessory to the microscope, such as the universal stage, which although allowing rotation of the crystal necessitates auxiliary stereographic projection and is often considered laborious in operation and is not widely employed.
The significance of tridymite in igneous and metamorphic petrogenesis
Authors: Black George P.
Published: December 2006

Physico-Chemical data clearly show that the presence of tridymite in a rock indicates the prevalence not only of high temperatures, but also of relatively low pressures during the formation of that rock. Whereas many authors (e.g. Shand, 1927; Larsen, 1936) have used tridymite as an indicator of temperature, the importance of tridymite as an indicator of pressure has been largely overlooked.

Although the presence of tridymite is by itself sufficient to enable the pressure, and hence the depth, at which a rock formed to be estimated within certain limits, the presence of tridymite in association with some other pressure-or temperature-indicating mineral allows much closer limits to be set.
The occurrence of palygorskite near Ipswich, Queensland
Authors: Rogers Lillian N. , Martin A. E. , Norrish K.
Published: December 2006

In the course of an investigation on the determination of soil carbonates a sample of dolomite, from the Ibis dolomite quarry, Mr. Flinders, Queensland, was examined by X-ray diffraction and found to contain palygorskite. As this appears to be the first recognition of the occurrence of the mineral in Australia and as it has a number of commercial uses (e.g. as a drilling mud, catalyst, decolorizer, and absorbent), further work was undertaken.
Rammelsbergite from the southern uplands of Scotland
Authors: Temple A. K.
Published: December 2006

During an investigation of the mineralization of the Leadhills- Wanlockhead lead and zinc mining district, rammelsbergite (NiAs2) was identified as an associate of niceolite (NiAs), reputed to have come from no. 4 level on the west branch of the New Glencrieff vein. The identification was confirmed on further material collected from the dumps at the Glenerieff mine, Wanlockhead, Dumfriesshire, and on specimens from the Scottish Mineral Collection (nos. 1952.5.18; 20; 21).
Transitional optics of some andesines and labradorites
Authors: Muir I. D.
Published: December 2006

Recent optical and structural investigations have shown that ; oth high- and low-temperature forms of plagioclase can exist naturally over the range An0-70, and in the more basic plagioclases (An70_90) Gay (1954) has shown that a structural distinction can be effected although no definite optical differences have yet been established. In the anorthite range slight optical and distinct structural differences have been observed between synthetic plagioelases and crystal lapilli on the one hand and all other natural plagioclases on the other (Gay, 1953).
Australites from Harrow, Victoria
Authors: Baker George
Published: December 2006

Thirty-Four specimens of australites were collected by Miss N. Jones and her brother Mr. Jones, during forty years while working on their property of 2000 acres, on the north bank of the Glenelg river. This is situated 3½ miles due east of Harrow (37° 8' S., 141° 33' E.) in the western district of Victoria, 236 miles north of west of Melbourne. The collection was kindly submitted for examination through Mr. E. D. Gill of the National Museum, Melbourne.
The Rev. William Gregor (1761-1817), discoverer of titanium.
Authors: Russell Arthur
Published: December 2006

In view of the important uses to which the metal titanium has been applied in recent years, it seems fitting that some tribute should be paid to its Cornish discoverer, the Rev. William Gregor, and with this end in view I have collected the following facts concerning this now almost forgotten distinguished early chemist.

The Rev. William Gregor, M.A., chemist and mineralogist, was the younger son of Francis Gregor, member of an old Cornish family of Trewarthenic, Cornelly, CornwalI. Born on December 25, 1761, he was educated at Bristol Grammar School, and it was while there that he first developed a taste for chemistry.
Manganese amphiboles from Chikla, Bhandara district, India
Authors: Bilgrami S. A.
Published: December 2006

The four amphiboles described in this paper were collected during the summer of 1950 from the Sitasaongi mine. This mine, which produces high-grade manganese ore, is situated in the Chikla area, Bhandara district, India. The ore band is 8 to 18 feet thick and is strongly folded and faulted at many places (fig. 1). The most common rock types in the area are: calc-granulites, calc-gneisses, mica-schists, quartzites, gondite (quartz-spessartine-rock), injection gneisses, and pegmatites. The pegmatites are the youngest and cut through the manganese-ore band as well as the country-rocks. All are of Archaean age.
The effect of isomorphous substitutions on the intensities of (001) reflections of mica- and chlorite-type structures
Authors: Brown George
Published: December 2006

A widely used method of quantitative analysis in clay mineralogy . is the comparison of the intensities of X-ray reflections from a socalled standard mineral with the unknown. In the clay minerals where isomorphous substitution is frequent the term 'mineral' generally covers a range of compositions and what is meant by such a term is a group of closely similar minerals. The so-called standard mineral is any member of a group which the particular worker may have in a pure or almost pure condition. If the standard mineral and the mineral in the unknown give different intensities for an equal volume of material the results will be inaccurate.
The hydration of larnite (β-Ca2SiO4) and bredigite (α1-Ca2SiO4) and the properties of the resulting gelatinous mineral plombierite
Authors: McConnell J. D. C.
Published: December 2006

In this paper the formation of a gelatinous hydrate phase from the natural dicalcium silicate minerals larnite and bredigite is described. Detailed study of the gel so formed indicates that the process of hydration is a solid reaction which is effeeted by diffusion. The preferred orientation of the hydrate phase suggests that the hydration is facilitated by a relationship between the structure of the anhydrous silicate and that of the hydrate phase produced.

In this investigation the variations in density, mean refractive index, and chemical composition of the natural gels have been determined and the characteristics of the adsorbed water studied by isothermal dehydration and rehydration. In discussing the mechanism of hydration it has been assumed that this obtains at constant volume. This assumption is based on the study of gel pseudomorphs after single crystals of larnite and bredigite in thin section.
Disordered structural states in the dehydration of goethite and diaspore
Authors: Lima-de-Faria J. , Gay P.
Published: December 2006

Single crystal X-ray studies of the dehydration of goethite to hematite at low temperatures show that satellite reflections occur close to the hematite diffraction spots. At higher temperature these satellites are replaced by diffuse intensity regions, which disappear on further heating. The satellites are situated on each side of hematite spots on reciprocal lattice lines parallel to the c*-axis of the hematite; their spacing corresponds to a periodicity in direct space of about 32 Å. A similar phenomenon is observed on the dehydration of diaspore to corundum, with a spacing for the satellites of about 39 Å.

The mode of occurrence of the satellites, both in position and intensity, could correspond to a sinusoidal or square-wave structure amplitude modulation along the c-axis of the hematite and corundum crystallites, before dehydration is complete.
The Wairarapa Valley, New Zealand, Chondrite
Authors: Battey M. H.
Published: December 2006

The Wairarapa Valley hypersthene-olivine chondrite, found about 1863, has been analysed with the following result: SiO2 35·72, TiO2 0·11, Al2O3 2·91, Cr2O3 0·48, FeO 12·42, MnO 0·28, MgO 23·28, CaO 1·73, Na2O 0·96, K2O 0·20, P2O5 0·31, Fe 12·61, Ni 1·50, Co 0·04, FeS 5·46, Cl 0·07, H2O+ 1·05, H2O− 0·48, less O for Cl 0·03; total 99·58 %. D. 3·65. The phases present are kamacite, taenite, plessite, troilite, magnetite, chromite, olivine Fa16, bronzite Fs15, possibly enstatite, plagioclase An25, and (?) maskelynite An9. The structures of the silicate phases and those disclosed by etching the metal phase are illustrated and described.
Optical determination of aegirine-augite with the universal stage
Authors: King Basil C.
Published: December 2006

The accurate determination of α:[001] and 2V in members of the aegirine-augite series often presents difficulties owing to strong absorption and dispersion, especially as high angles of tilt on the universal stage are often involved. Both of these angles depend on the location of α, and this operation is the one most subject to error.

An alternative procedure is the determination of A:[001], the angle between an optic axis and [001]. This angle is very easily and accurately determined and varies systematically with composition. It can be derived from the values for α:[001] and 2V, while conversely values of α:[001] and 2V can be obtained from A:[001] by reference to standard curves.
Quartz after tridymite in an acid intrusion from Mull
Authors: Skelhorn R. R.
Published: December 2006

The occurrence of tridymite, now inverted to quartz, in a craignurite (allied to granophyre) from Craignure, Mull, is described. An account of the field occurrence and petrology and a new analysis of the craignurite are given. The significance of the occurrence of tridymite is discussed in the light of recent experimental studies.
Strontium in plagioclase feldspars from four layered basic masses in Somalia
Authors: Butler J. R. , Skiba W.
Published: December 2006

The petrological and structural characteristics of four layered basic masses in Somalia are described. Sr contents of feldspars from three of the masses are similar for comparable An contents; Sr varies between 1000 and 1850 p.p.m. and tends to increase as An decreases from An68 to An48. In feldspars from the other mass Sr also increases with decreasing An content (An74 to An56), but is at a much higher general tenure (1650 to 2350 p.p.m.). It is concluded that the four masses were not all part of the same layered intrusion.
Low-temperature thermal effects in natural volcanic glasses due to strain
Authors: Ewart A. , Fieldes M.
Published: December 2006

Sharp exothermic peaks occurring at about 90° C during D.T.A. treatment of natural volcanic glasses are described and are shown to be due to release of external strain. This is probably triggered by loss of surface water. No systematic variation in strain could be found in glass of different geological histories, but strain is found to decrease during natural weathering of volcanic glasses. Differences in weatherability of natural glasses may be related to degree of surface strain.
An improved technique for producing thin rock-sections
Authors: Bishop A. C.
Published: December 2006

The preparation of thin rock-sections using a modified high-speed surface grinding machine is described. The machine is fitted with a new type of jig designed to hold ¼ in. thick glass slides to which the rock slices are mounted for grinding. The machine operates automatically once a cut is set and the large size of the jig enables fifteen 3 in. × 1 in. sections to be produced at one grinding operation without the constant attention of an operator.
Cobaltic hydroxide in nature
Authors: Hey M. H.
Published: December 2006

Natural cobalt hydroxide is CoO.OH, not Co(OH)2 as has recently been asserted; for this mineral the name heterogenite has priority. Copper, frequently present, may be in solid solution as (Co,Cu)(O,OH)OH, or may be as finely divided malachite; for cuprian heterogenite, the name schulzenite has priority.
β-Ferric oxyhydroxide—akaganéite
Authors: Mackay A. L.
Published: December 2006

A new mineral, akaganéite, has been found in limonite deposits and has been shown to be identical with synthetic β-FeOOH. It contains no chlorine. The micro-morphology of β-FeOOH as it occurs as akaganéite and as it is produced by a solid-state transformation from FeCl2.4H2O , by the hydrolysis of dilute FeCl3 solutions, and by the hydrolysis of very concentrated FeCl3 a solutions, has been studied, chiefly by electron microscopy and diffraction. Some modes of colloidal association of the particles of β-FeOOH are described.
The origin of stannite by replacement of cassiterite in the Turkaňk zone of the Kutná Hora ore deposit
Authors: Novák F. , Blűml A. , Tacl A.
Published: December 2006

The trace-element assemblage of the cassiterite of the Turkaňk and Rejsy zones of the Kutná Hora mining district are typical of a hydrothermal sulphide-cassiterite formation. Polished section studies show replacement of cassiterite by pyrrhotine, with stannite as am intermediate zone.
The identity of almeriïte with natroalunite
Authors: Hoyos de Castro A. , Alías L. J.
Published: December 2006

Two specimens of almeriïte from the type locality have been examined by chemical analysis, d.t.a., and X-ray powder photography and shown to be identical with natroalunite. A little illite and kaolinite are present as impurities. X-ray powder data for natroalunite are presented.