bluuebunny/crossref_metadata_2025 huggingface dataset:
A note on the relationship between the precision of classical methods of rock analysis and the concentration of each constituent
Authors: Ahrens L. H.
Published: December 2006

A Granite (G-1) from Westerley, Rhode Island, and a diabase (W-1) from Centerville, Virginia, were recently analysed by some 34 analysts in different countries for the purpose of obtaining thoroughly reliable rock standards for spectrochemical analysis. Most determinations were made by so-called classical methods of chemical analysis. The results of the investigation have been discussed by Fairbairn and others. Fairbairn examined the results statistically and, using the relative deviation (standard deviation expressed as a percentage) as a measure of precision, concluded that precision deteriorated with a decrease in the concentration of a constituent. In the present paper this general observation will be demonstrated quantitatively by means of a graphical presentation, thus providing the petrologist with a guide for rapidly assessing and comparing the precision of classical methods of chemical analysis over considerable concentration ranges.
An occurrence of palygorslcite in the Shetland Isles
Authors: Stephen I.
Published: December 2006

In May 1950 the writer received from Mr. Henry Burgess, of Spiggie, Shetland Isles, a specimen of a material which had been found by a local quarryman. The property of the material which had particularly attracted attention was that when it absorbed water it became soft and pliable and looked like wet leather. The specimen, measuring approximately 4x2X1 inches, had a brownish iron-stained outer skin, and showed slight signs of foliation parallel to its length. Internally it consisted of a white to greyish-white compact material, in which were embedded portions of the syenitie country-rock. This white material has been shown to consist dominantly of the mineral palygorskite (attapulgite).
Investigation of the crystal structure of antigorite
Authors: Zussman J.
Published: December 2006

Selfridge (1936) examined by chemical, optical, and X-ray powder methods a large number of specimens of serpentine minerals (ideal formula H4Mg3Si2O9), many of which were known as antigorite. He found that nearly all gave similar powder photographs, indicating a close structural relationship, but that there were noticeable differences on the basis of which the specimens could be separated into two groups, one giving a photograph similar to that of chrysotile asbestos, and the other containing the varieties called antigorite. Gruner (1937) came to similar conclusions, and in addition he indexed most of the reflections using the cell dimensions a 5.33, b 18.5, c 2 x 7.33 Å., β 93°, remarking in particular on the correspondence between 001 reflections in the two groups.
Rodingite from the Girvan-Ballantrae complex, Ayrshire
Authors: Bloxam T. W.
Published: December 2006

Occurrence and relationships. Altered and garnetized gabbros occur in association with serpentinite occupying the lower south-eastern slope of Byne Hill, one mile to the south of Girvan. The rocks crop out above Balaclava Wood near the footpath from Bynehill Bridge to Craiglea. Although the precise form of the altered gabbros is not very well revealed, they appear to be dikes intrusive into the surrounding serpentinized harzburgite. Contacts with the serpentinite are exposed in two places but are evidently lines of later movement. The relationships of these altered gabbros to the main gabbro mass of Byne Hill are obscure. They are, however, probably contemporaneous, since sporadic garnetization of the main gabbro occurs along its contact with serpentinite farther to the south-west.
Space lattices
Authors: Tomkeieff S. I.
Published: December 2006

The concept of a space lattice is fundamental in crystallography. A space lattice, or more simply a lattice, is an indefinitely extended regular array of points, in which the environment of each point is exactly the same. This implies that if the lattice is (1) translated parallel to itself, or (2) inverted about one of its points, or (3) rotated it will remain precisely the same as it was before such transformations. Such projective transformations as translation, inversion, or rotation are called symmetry operations. A lattice therefore may be said to be invariant in respect to certain specific symmetry operations. It is then said to possess certain symmetry elements.
Grovesite, the manganese-rich analogue of berthierine
Authors: Bannister F. A. , Hey M. H. , Campbell Smith W.
Published: December 2006

A Dark brown (blackish-brown) mineral forms a thin crust on manganese ore on the specimen [B.M. 1944,35] from no. 5 orebody of the Benallt mine, Rhiw, Carnarvonshire, North Wales. This is the specimen on which the first measurable crystals of banalsite were discovered in 1944 (Min. Mag., 1945, vol. 27, pp. 63-64). The mineral occurs as closely-packed, small rosettes, at most 0"5 ram. across, and is partly coated with a thin layer of baryte. An X-ray photograph by Dr. Bannister suggested that the mineral might belong to the chlorite group. Its optical properties were determined and nothing further was done with it at the time.
The determination of composition and thermal history of plagioclase by the X-ray powder method
Authors: Goodyear J. , Duffin W. J.
Published: December 2006

In a recent paper (hereafter referred to as GD) Goodyear and Dufiln (1954) described X-ray powder data for a number of synthetic and chemically analysed plagioclases of composition An0Abl00-Anl00Ab0. Important aspects of this work were a correlation of the X-ray patterns with chemical composition, and a distinction between the pattern of a naturally occurring material of low-temperature origin and that of a synthetic of similar composition. The investigation showed quite clearly that the unit-cell dimensions of a synthetic plagioelase depend but little on composition from An0Abl00 to An70Ab30, whilst they differ from those of the low-temperature modification greatly for albite, to a lessening degree as the composition approaches An70Ab30, and practically not at all in the range An70Ab30-Anl00Ab0.
Projector for interference figures and for direct measurement of 2V
Authors: Vincent H. C. G.
Published: December 2006

The instrument is designed for the study and measurement of the optical characters of crystals and anisotropic materials. The conoscopic phenomena, over a wide area for any selected orientation of the specimen, may be brought into view on a hemispherical screen, without the use of a microscope or lens system. The parts of the interference figure retain their true angular relationships, directly displaying for observation or measurement values of 2V for any angular separation of the optic axes.
Isokite, CaMgPO4F, a new mineral from Northern Rhodesia
Authors: Deans T. , McConnell J. D. C. , Pickup R.
Published: December 2006

The mineral, for which the name isokite is now proposed, occurs in the carbonatite plug which forms Nkumbwa Hill Oat. 10° 10' S. long. 32° 51' E.), 15 miles east of Isoka (pronounced Iso̅ka) in Northern Rhodesia. A preliminary account of this interesting mineral locality has already been published (Reeve and Deans, 1954) and a more detailed account is now in preparation, so that only the main features of the occurrence need be mentioned here. The carbonatite plug or pipe, 0.6 by 1 mile across and rising to a height of 1000 feet above the surrounding country, pierces granitic and micaceous gneisses which are fenitized to a distance of 500 yards from the walls of the pipe, but, unlike the classic carbonatite complexes, no intrusive alkalic rocks are exposed.
Wairakite, the calcium analogue of analcime, a new zeolite mineral
Authors: Steiner A.
Published: December 2006

During the study of hydrothermal alteration of cores recovered Dfrom holes drilled at Wairakei during the exploration for geothermal steam, an unusual zeolite mineral was found. Optical, chemical, and X-ray data indicate that this zeolite is a new mineral, the calcium analogue of analcime. The name wairakite is given to the new mineral after the locality Wairakei in New Zealand. Wairakei is situated in the central part of the North Island, approximately 4 miles north-north-east from Lake Taupo, in an active volcanic region. The material was submitted to Dr. D. S. Coombs, Department of Geology, University of Otago, Dunedin, for an investigation of its X-ray crystallography.
X-ray observations on wairakite and non-cubic analcime
Authors: Coombs D. S.
Published: December 2006

Mr. A. Steiner has kindly invited the present writer to study by X-ray methods the new mineral wairakite described by him in the preceding pages. The material provided includes an incomplete octahedron 15 ram. across with small modifying ieositetrahedron-like faces, and some smaller partial icositetrahedra. Faces are dull and give diffuse reflections oil the optical goniometer, but, by attaching small pieces of glass cover-slip to improve the reflections, interfacial angles approximating to those of the cubic forms {111} and {211} were measured. As pointed out by Mr. Steiner, however, the mineral is birefring'ent, biaxial, and finely twinned. A preliminary small-diameter X-ray powder photograph taken by Mr. N. Wells of the Soil Bureau, Wellington, showed an apparently cubic, analeime-like pattern (personal communication).
Gedrite from Glen Urquhart, Inverness-shire
Authors: Francis G. H.
Published: December 2006

This note describes a hydrous gedrite from Glen Urquhart for which the presence of an appreciable excess of oxygen atoms over the normal 96 per unit cell has been established. This is associated with an approximately equal deficiency of cations. The type of isomorphous replacement here discussed is hitherto unrecorded in the amphibole group.
The structural formula of a hydrous amphibole
Authors: Nicholls G. D. , Zussman J.
Published: December 2006

The majority of amphiboles conform to the general structural formula X2-3Y5Z8O22(OH,F,Cl)2, where X = Na, K, Ca, Y - Mg, Fe″, Mn, A1, Fe‴, Ti, and Z = Si, A1 or Ti. Two X ions occupy the positions filled by Ca in the ideal tremolite structure; the additional X ions are assumed to occur in the 'A' sites which are vacant in tremolite.

For the amphiboles, therefore, the method most commonly adopted for deriving a formula from a chemical analysis is to assume that a total of 24 anions is present in the formula unit.
On the occurrence of the rare copper molybdate, lindgrenite, at Brandy Gill, Carrock Fell, Cumberland
Authors: Kingsbury Arthur W. G. , Hartley J.
Published: December 2006

Lindgrenite, a basic copper molybdate Cu3(MoO4)2(OH)2, was first described in 1935 by Palache from the oxidized zone of the great copper deposit at Chuquicamata, province of Antofagasta, Chile. A second occurrence has been recently described from the Helena mine in the Seven Devils mining district, Adams Co., Idaho, the first recorded in the U.S.A. In this paper we are able to record a third occurrence; this time in Cumberland, adding another species to the list of British minerals.
Movement of screw dislocations in hematite.(With Plates I and II.)
Authors: Seager A. F. , Sunagawa I.
Published: December 2006

The surface structure of the basal pinacoid of crystals of hematite has been studied by phase contrast microscopy, yielding evidence of the movement of dislocations after the cessation of growth. Steps due to such movement are initiated from the centre of growth spirals, and cross the growth fronts without interrupting the growth layers. Viewed from the dislocation the step has the higher side on the left for right-handed spirals and vice versa. In the majority of cases the step is straight, but rarely it is curved or kinked. It is proposed to call such steps ‘dislocation scarps’.

The number and length of dislocation scarps vary considerably in crystals from different localities. These variations probably reflect differences in the stress history of the crystals.
The effect of 'impure' pore fluids on metamorphic dissociation reactions
Authors: Wyllie Peter J.
Published: December 2006

Comparison of experimental data from the systems MgO-CO2-H2O (closed) and MgO-CO2-A (simulating an open system) shows that the effects of H2O and A on the dissociation of magnesite are almost identical; both behave as inert components reducing the partial pressure of CO2. The dissociation temperature at constant total pressure is lowered according to the proportion of inert volatiles in the initial vapour phase. The dissociation is completed at one temperature (univariant) in an open system but in a closed system it proceeds through a temperature interval (divariant) because the vapour phase changes composition. The amount of dissociation remains small until the upper limit of the interval is reached. More complex dissociation reactions in the systems CaO-MgO-CO2-H2O and CaO-SiO2-CO2-H2O are described; they follow similar patterns. Under closed or partially open metamorphic conditions non-reacting pore fluid components (inert) have to be treated as one additional component for application of the mineralogical phase rule. Comparison of the pattern of metamorphic parageneses with the patterns of reactions occurring under known experimental conditions may provide information about metamorphic processes. Metamorphic reactions can be represented within a petrogenetic model with axes P, T, and pore fluid composition varying between H2O and CO2.
Ferrodiorite from the Isle of Skye
Authors: Wager L. R. , Vincent E. A.
Published: December 2006

As a preliminary to an account of the marscoite suite of the Western Redhills Tertiary igneous centre of Skye, a description is given here of one unit, the ferrodiorite. While accepting Harker's hypothesis of the hybrid origin of marscoite (1904, pp. 175–196) we consider that the ferrodiorite, with which marscoite on Marsco is associated, is not itself a hybrid, but one of the parents from which the hybrids were formed. Among Thulean igneous rocks the ferrodiorite has mineralogical and chemical affinities with Hebridean mugearites, on the one hand, and with the ferrogabbros of the Skaergaard intrusion on the other, but is probably significantly different from both.
Heat treatment of chevkinite and perrierite
Authors: Lima-de-Faria J.
Published: December 2006

Standard heat treatments of 700° C for 3 hours, 1000° C for 1 hour. and 1300° C for 1 hour, both in a nitrogen atmosphere and in air, were applied to several samples of chevkinite and perrierite, and X-ray powder photographs were taken of the unheated and the heated materials.

Metamict chevkinites from the Urals, USSR, and from Ifasina, Madagascar, give the chevkinite phase when heated in nitrogen at 1000° C for 1 hour, but when heated in air at 1300° C for 1 hour give the perrierite phase. Perrierites only give the perrierite phase when heated in air or in nitrogen. A criterion for the identification of metamict samples of these two minerals was deduced from these experiments.
Extinction curves and 2V: a stereographic solution
Authors: Tocher F. E.
Published: December 2006

Utilizing the Biot-Fresnel construction in reverse, the magnitude and sign of the optic axial angle of a biaxial crystal are determinable from the stereogram of the extinction curves. Refinements in the determination of the extinction curves include the use of conoscopic observations, and of crystal cylinders instead of irregular fragments or entire crystals. Direct 2V measurements on some of the material investigated by this method show that this indirect and graphical approach permits the location of each optic axis to within ¼° of its true position.
Crystal chemistry of ettringite
Authors: McConnell Duncan , Murdoch Joseph
Published: December 2006

Crystal-chemical calculations are based on three chemically analysed samples of ettringite and their respective unit-cell dimensions and specific gravities. The large hexagonal unit cell is deduced to contain 384 oxygen atoms, 64 cations with co-ordination number 6 or more, and 48 cations with co-ordination number 4 or less. Some substitution of cations with co-ordination number 3 apparently takes place, and any excess above 192 H2O takes place in the form of substitution of (H4O4) for XO4 anionic groups. The isomorphism is extremely complex but can be generalized in simple form as 16[A4(XO4)3(H2O)12], where A represents atoms with six-fold co-ordination (Ca, Na, Al) and X represents atoms with four-fold coordination (S, Si, H4, and possibly some of the Al). It is implied that an isostructural series of silicon-containing calcium aluminium sulphate hydrates might exist, the extreme compositions of which are: 6CaO.Al2O3.3SO3.3SiO2.24H2O and 6CaO.Al2O3.3SO3.30H2O.
Pantelleritic liquids and their phenocrysts
Authors: Carmichael I. S. E.
Published: December 2006

The phenocrysts of four porphyritic obsidians from Pantelleria have been analysed chemically, together with the residual glasses (liquids). Three new analyses of anorthoclase (one partial analysis), two of sodic ferrohedenbergite, one of fayalitic olivine, and two of cossyrite are presented together with their optical properties, and the relationship of these phenocrysts to their liquids is considered.

The experimental studies in the system NaAlSi3O8-KAlSi3O8-SiO2-H2O show that for synthetic liquids of similar composition to the normative salic constituents of the pantelleritic liquids, a potassic alkali feldspar crystallizes, whereas in the pantelleritic liquids phenocrysts of anorthoclase (Ab67–Ab61) occur. It is suggested that sodium metasilicate, which appears in the norms of all the pantelleritic liquids, may be responsible for the divergence in trend between the synthetic feldspar-liquid tie-lines and the pantelleritic feldspar-liquid tie-lines.
Electron-diffraction study of subsidiary maxima of scattered intensity in nepheline
Authors: McConnell J. D. C.
Published: December 2006

A detailed electron and X-ray diffraction study of a suite of nephelines from a wide range of paragenetic environments indicates that, in all cases studied, additional weak maxima of scattered intensity are present. Similar intensity maxima have previously been observed and described in an isolated case by Sahama. Thermal treatment at temperatures as low as 200° C causes these maxima to become noticeably diffuse, implying a structural transformation.
Observations on the rhombic section of a zoned
plagioclase crystal
Authors: Vance Joseph A.
Published: December 2006

A zoned plagioclase crystal from a magmatic quartz-diorite shows two generations of pericline twinning: one growth twinning, the other glide twinning. Plotting the angle of the rhombic section against composition for each set of twins gives curves indicative of an intermediate structural state with respect to the theoretical curves determined by Smith (1958). The curve for the growth twins is closer to the high structural state than that for the glide twins and supports the primary origin of the former. This curve is believed to fix approximately the lowest structural state at which primary pericline twinning can develop in magmatic rocks. The lack of coincidence of the curves for the two generations of twinning indicates partial inversion prior to formation of the glide lamellae, while the position of the curve for these secondary lamellae suggests a genetic relation to inversion. Both rhombic sections are probably relict with respect to the present structural state. The form of the curves confirms the general accuracy of Smith's curves for the maximum high and low structural states.
The ageing of sesquioxide gels. II. Alumina gels
Authors: Mackenzie R. C. , Meldau R. , Gard J. A.
Published: December 2006

Aluminium oxides occur widely in soils and are of considerable pedological significance. The ageing of alumina gels, prepared from aluminium chloride and ammonia, into crystalline hydroxides has been investigated using thermal, X-ray, infra-red, and electron-microscope techniques. At room temperature ageing is more rapid at high pH values. The structure of the original gel particles appears to resemble boehmite and ageing causes the formation of bayerite with small amounts of gibbsite. The morphology of the various mineral types is considered and a mechanism of ageing suggested.
Powellite from Traprain Law, Haddingtonshire, Scotland
Authors: Battey M. H. , Moss A. A.
Published: December 2006

Powellite, appearing to be of primary late-magmatic origin, has been found associated with analcime, apophyllite, and calcite in a geode in phonolite. Data are: D 4·40, ε 1·984, ω 1·971, a 5·20 Å, c 11·43 Å, CaO 27·8, MoO3 61·8 (av.), WO3 11·4 (av.).
The production of wooden replicas of natural crystals
Authors: Brebner G. G.
Published: December 2006

A cutting technique, based on the use of carefully prepared plan projections, has been evolved for the making of unlimited numbers of accurate wooden replicas of natural crystals.
Garronite, a new zeolite, from Ireland and Iceland
Authors: Walkee G. P. L.
Published: December 2006

A new zeolite closely related to phillipsite and gismondine is recorded from thirty localities in the Tertiary basalts of Antrim and eastern Iceland, and the name garronite is proposed. Four chemical analyses indicate a composition of NaCa2·5A16Si10O32.13·5H2O. Garronite differs chemically from phillipsite in having a very low content of potash, and from gismondine in containing less lime, alumina, and water; optically garronite is intermediate between these two zeolites.
Low-potash gismondine from Ireland and Iceland
Authors: Walker G. P. L.
Published: December 2006

Gismondine is recorded from the Tertiary basalts of the North Atlantic region, from a total of some 40 localities in Antrim and Iceland. It occupies a well-marked position in the sequence of zeolite zones in the lavas, and the characteristic associates are chabazite, thomsonite, and phillipsite. Five new chemical analyses of gismondine from these localities show a negligible content of potash, and indicate plagioclase-type substitution, giving a series ranging from near Ca8Al16Si16O64.34H2O to near Na2·5Ca5·5Al13·5Si18·5O64.34H2O. Substitution of NaSi for CaAl leads to a decrease in refringence, birefringence, and density.
Framework structures formed from parallel four- and eight-membered rings
Authors: Smith J. V. , Rinaldi F.
Published: December 2006

Feldspars, paracelsian and danburite, harmotome and phillipsite have alumino-silicate frameworks that consist of three out of the seventeen simplest ways of cross-linking chains of the feldspar type. The four-membered rings that form the feldspar type of chain are parallel and have two adjacent tetrahedra pointing one way and the other two the other way. Chains are produced by sharing oxygen atoms of oppositely-pointing tetrahedra of parallel four-membered rings. Cross-linking of chains produces frameworks containing parallel eight-membered rings. If alternate tetrahedra in the rings point the same way, a new type of chain is produced, and there are four simple ways of joining these chains together to make a framework. If all four tetrahedra in a ring point the same way, only one structure can be developed, which has been proposed already by Barrer et al. for the zeolite Na-P1 and other members of the harmotome family. If three tetrahedra in the ring point the same way, very many simple structures can be constructed, and the seven simplest of these are described. It is suggested from comparison of cell dimensions that gismondine and, perhaps, yugawaralite may belong to this series of hypotheti- cal structures. It is also suggested that some of the complexity and confusion in the harmotome group of zeolites may arise from hitherto unrecognized members of this hypothetical group. Major angular distortions from the ideal shape occur for the naturally-occurring silicates belonging to these structural groups.
Location of argon and water in cordierite
Authors: Smith J. V. , Schreyer W.
Published: December 2006

Evaluation of X-ray powder diffraction data shows that argon atoms (radius 1·9 Å) lie at the centres of the large holes in the cordierite structure. The reflection intensities for hydrous cordierite differ from those for anhydrous cordierite but to a lesser degree than those for argon-bearing cordierite. Although analysis is uncertain, it appears that the smaller water molecules (radius 1·4 Å) do not occupy either the centres of the six-membered rings or the centres of the large cavities. It is possible that they may be attached to the walls of the large cavities or occur partly as hydroxyl groups in the framework. Single-crystal X-ray analysis is necessary to resolve this problem.
Goyazite and florencite from two African carbonatites
Authors: McKie Duncan
Published: December 2006

Florencite with ω 1·653, εd 1·661, G 3·457, a 6·971 ± 0·004 Å, c 16·42±0·13 Å, and rhombohedral unit-cell contents Sr0·42Ce0·52Ca0·14Al2·83(PO4)1·77(SO4)0·10 F0·41(OH)5·24(H2O)0·85 occurs in the Kangankunde carbonatite in Nyasaland, and goyazite with G 3·386, a 6·982±0·001 Å, c 16·54±0·02 Å, and rhombohedral unit-cell contents Ba0·05Sr0·50Ce0·41Ca0·08A2·78(PO4)1·62(SO4)0·19F0·30(OH)5·30(H2O)1·18 on the Wigu carbonatite in Tanganyika. Hydrothermal decomposition experiments in the Wigu material indicate stability below 535 ± 10 °C at pH2O 200 bars and 565 ± 10°C at pH2O 2500 bars ; both minerals exhibit endothermic peaks at 630°C in differential thermal analyses. The crystal chemistry of the goyazite series is discussed in the light of the two new analyses and of newly determined unit-cell dimensions for four other members of the goyazite series. Goyazite, florencite, and gorceixite appear to have crystallized during late-stage replacement processes or under supergene conditions in carbonatites.
Some petrological aspects of order-disorder in feldspars
Authors: Marfunin A. S.
Published: December 2006

The results are presented of some recent feldspar studies that relate the fundamental concepts of order-disorder series to petrological problems. New diagrams have been prepared with coordinates ‘optical properties-chemical composition-structural state’. From direct observations made on natural minerals some conclusions have been reached about the sequence in which the solid-state transformations of ordering, unmixing, and twinning occur in feldspars.

A study has been made of the geological distribution of different structural types of alkali feldspars in single intrusive bodies (Tertiary granite, Palaeozoic syenite, Pre-cambrian charnockite), in magmatic complexes, and in different complexes of the Ukrainian Shield and the Caucasus Geosynclinal Province.
Metamorphic pyroxenes from the Broken Hill district, New South Wales
Authors: Binns R. A.
Published: December 2006

The Archean rocks of the Barrier Ranges, New South Wales, show zones of progressive regional metamorphism of which the highest is characterized by orthopyroxene-bearing basic granulites. Within this zone, further increase in metamorphic grade results in a detectable change in distribution of ferrous iron and magnesium between coexisting orthopyroxene and clinopyroxene, the latter becoming relatively richer in iron. Mutual solid solution between the two pyroxene phases also appears to increase. The value of coexisting pyroxenes as indicators of metamorphic grade is thus established. There are some points of disagreement between the Broken Hill results and previously advanced theories of cation distribution in pyroxenes.
An occurrence of nephrite jade in West Pakistan
Authors: Butler B. C. M.
Published: December 2006

Two pebbles of good quality nephrite from Kohat District are described and the possible origin of the stones is discussed. The discovery is of significance in relation to the unsolved problem of the origin of the raw material of Indian carved jade.
Rosasite, aurichalcite, and associated minerals from Heights of Abraham, Matlock Bath, Derbyshire, with a note on infra-red spectra
Authors: Braithwaite R. S. W. , Ryback George
Published: December 2006

Rosasite and aurichalcite occur with other copper, zinc, and also lead minerals in Masson Cavern, Rutland Cavern, and other workings in the Heights of Abraham, Matloek Bath, Derbyshire. Partial analyses of two specimens each of rosasite and aurichalcite show Cu : Zn ratios typical of the respective species. They appear to have been formed by the action of solutions containing zinc on disseminated chalcopyrite. The infra-red absorption spectra of malachite, rosasite, aurichalcite, and hydrozincite, examined by the mull technique, are shown to fall into two groups corresponding with the structural groups established by X-ray work. Twin absorption maxima at O-H stretching frequencies are present in the spectra of malachite and of rosasite.
Epididymite and milarite—alteration products of beryl from Věžná, Czechoslovakia
Authors: Černý P.
Published: December 2006

Epididymite, determined by means of its optical properties, X-ray powder pattern, and spectrographic analysis, was found in a desilicated pegmatite near Věžná, Western Moravia, Czechoslovakia. It was formed contemporaneously with minor amounts of milarite in a late hydrothermal stage by the action of sodium-rich solutions on beryl. This is the first occurrence of epididymite and milarite as alteration products of beryl and the first findings of epididymite in any other paragenesis than that of alkaline pegmatites. The optical properties of epididymite are re-examined and older data rejected.
The chemistry and mineralogy of the olivine nodules of Calton Hill, Derbyshire
Authors: Hamad S. el D.
Published: December 2006

Chemical analyses, optical data, and cell parameters are given for olivine (Fo90·3 and Fo91·4), orthopyroxene (Ca1·5Mg89·0Fe9·5 and Ca9·8Mg88·6Fe10·6), clinopyroxene (Ca39·6Mg55·8Fe4·6), and chromian spinel from olivine nodules from the Carboniferous basalt of Calton Hill, Derbyshire. Chemical and modal analyses of the nodules and of their host rock are also presented. The distribution of Mg and Fe in the coexisting pyroxenes is fairly similar to that observed by Ross, Foster, and Myers (1954) but differs slightly in that the extension of the pyroxene tie-line intersects the Ca-Mg side of the Ca-Mg-Fe triangle. The clinopyroxene is a normal augite rather than the hydrous augite previously reported (Tomkeieff, 1928). The high chromium content of the spinel and clinopyroxene contrasts with the low value for this element in the host rock, suggesting that these minerals are not differentiates of the basaltic magma: the nodules are considered to represent fragments from a deep-seated peridotite.
X-ray study of woodruffite from Sandur ore deposits, Mysore State, India
Authors: Naganna C. , Bouška Vl.
Published: December 2006

The mineral woodruffite, which has so far been reported from only one locality, Sterling Hill, New Jersey, has been found to occur in the Sandur area. Its physical and chemical characters are given. Indexing of the X-ray powder photograph shows that the mineral is most probably tetragonal with a 8·42, c 9·28 Å.
A continuous monochromatic interference filter
Authors: Harrison R. K. , Day G.
Published: December 2006

A simple form of adjustable monochromatic interference filter, suitable for both transmitted- and reflected-light microscopy, is described and figured.
The occurrence of eclogite on the Lyell Highway, Tasmania
Authors: Spry Alan
Published: December 2006

Eclogite occurring about 20 miles east of Queenstown, Tasmania, is the first example of this kind of rock to be described in detail from Australia. It has the chemical composition of a basic igneous rock and consists of garnet (A115.8Fe‴0.6Fe″10.0Mg7.3Ca5.7Si24O96) and pyroxene (Ca4.5Na2.5Mg3.7Fe″0.7Fe‴0.4Ti0.1Aliv3.7Aliv0.7Si15.3O48)with amphibole, muscovite, zoisite, quartz, rutile, and pyrite. The eclogite consists of lenticular bodies within Precambrian garnetiferous schists.
Phosphate minerals in a calculus from the reticulo-rumen of the sheep
Authors: Ellis S. E.
Published: December 2006

Brushite occurs as radial-concentric layers of prismatic crystals deposited on baked pellets of bentonite impregnated with cobalt oxide, placed in the reticulo-rumen of lambs as a preventive of cobalt-deficiency diseases. Collophane-like whitlockite, apparently pseudormorphous after brushite, occurs underneath the brushite layers, and struvite is found as rare minute crystals between the whitlockite and brnshite layers. Analytical and physical data are given for the first two minerals and the origin of the deposit is discussed.
The determination of the calcite : aragonite ratio in mollusc shells by X-ray diffraction
Authors: Davies T. T. , Hooper P. R.
Published: December 2006

By measuring the integrated line intensity on a Philips' X-ray diffractometer in place of the peak intensity and by paying due regard to the ease with which aragonite converts to calcite during cleaning and grinding operations, the proportion of calcite and aragonite in a pure calcium carbonate shell can be determined to within 1% of the total in less than 30 minutes.
An X-ray investigation of synthetic pyroxenes in the system acmite--diopside-water at 1000 kg/cm2 watervapour pressure
Authors: Nolan J. , Edgar A. D.
Published: December 2006

An X-ray investigation has been made of synthetic pyroxenes in the system acmite-diopside, crystallized at 750° C and 1000 kg/cm2 water-vapour pressure. Lattice parameters of these pyroxenes have been determined by least squares analyses of powder diffraction patterns and show an approximately linear relationship with composition, plotted as weight per cent. A rapid X-ray method has also been devised for the determination of the compositions of pyroxenes of this series.
Order-disorder in sapphirine
Authors: McKie Duncan
Published: December 2006

Yellow sapphirine with a doubled b-axis occurs in enstatite-hornblende-sapphirine rocks at the contact between dolomite marble and yoderite-quartz-talc schist on Mautia Hill, Tanganyika. It has refractive indices α 1·725± 0·002, γ 1·732±0·002, 2Vγ66°, pleochroism a pale yellow, β pale lime green, γ pale pinkish orange, and a composition corresponding to Mg3·67Mn0·04Fe2+0·17Ti0·01Fe3+0·33Als·07Si1·75O20·00. Its unit-cell dimensions are approximately a 9·85 Å, b 28·6Å, c 9·96 Å, β 110° 30′, and its diffraction pattern exhibits diffuse streaks parallel to b*, on which lie diffuse intensity maxima representing the relics of certain types of sharp reflexions of normal sapphirine ; this is interpreted as indicative of partial MgAl ordering. The associated enstatite and hornblende have compositions Mg7·58Mn0·02Fe2+0·02Ti0·01Fe3+0·13Al[6]0·25Al0·41[4]Si7·59O24·00 and K0·04Na0·16Ca1·95Mg4·37Mn0·01Fe0·052+Ti0·04Fe0·253+Al0·42[6]Al0·91[4]Si7·09O22·24(OH)1·76respectively and are accompanied by accessory hematite and pseudobrookite. Preliminary heating experiments have demonstrated the transformation of single crystals of partially ordered Mautia sapphirine to single crystals of a defect spinel phase after 48 hours at 1287° C in air; normal disordered Panrimali sapphirine remains unchanged by similar heat treatment.
The mineralogy and chemistry of the nickel carbonates
Authors: Isaacs T.
Published: December 2006

Nickel carbonate occurs in nature as a hexahydrate (hellyerite) and as a hydroxyhydrate (zaratite), but the anhydrous species is only known as an artificial product. All of the compounds show anomalous properties that have led to confusion in the literature.

Only the calcite structure was found for NiCO3; hydrothermal conditions appear to be essential for its synthesis, and a variation in cell size was found with changes in duration or temperature of synthesis, or both.

Hellyerite probably is [Ni(H2O)6]CO3, which would explain its ease of decomposition and rarity in nature. Zaratite is not a single mineral, but a composite of amorphous and fibrous components. The conditions under which NiCO3might be expected to occur are discussed. Nickel bicarbonate formed in the reactions to produce NiCO3; its X-ray diffraction pattern, indicating cubic symmetry, analysis, and optical properties are given.

The behaviour of nickel in these compounds is best explained in terms of crystal field theory.
Determination of 2V from one extinction curve and its related n0 curve
Authors: Joel N.
Published: December 2006

From the extinction curve of a biaxial crystal mounted on a spindle stage (or one-axis stage goniometer), the related n0 curve can be derived and drawn on the stereogram. The n0 curve is the equivibration curve—or constant-refractive-index curve—that goes through the projection P0 of the spindle-stage axis. After the principal diameters (maximum 2η and minimum 2ζ) of the no curve have been measured, the angle 2V may be calculated by means of the formula cos V = sin ζ/sin η. This method can also be used for determining—or refining—the directions of the principal axes α, β, γ.
The nomenclature of the natural alloys of osmium and iridium
Authors: Hey M. H.
Published: December 2006

An historical review of the nomenclature of the natural Os-Ir alloys suggests that the most suitable names are: For the cubic alloys, osmiridium (Steffens, 1824), i.e. osmian iridium; and for the hexagonal alloys, iridosmine (Breithaupt, 1827), i.e. iridian osmium, for alloys with 20% or more Ir, and native osmium for the very rare alloys with little or no Ir. Iridosmine may, if desired, be divided into two varieties, nevyanskite and sysertskite, following Rose and Haidinger.
A new incident illuminator for polarizing microscopes
Authors: Smith F. H.
Published: December 2006

The customary illumination by a ‘coverglass’ inclined at 45 degrees is replaced by a double reflection. The beam from the horizontal collimating tube is first reflected from a highly reflecting mirror at the back of the unit, then downward from a coverglass placed at the top of the unit. With this arrangement the coverglass is inclined at less than 22½ degrees to the axis of the microscope, with a similar reduction of the angle of incidence. The correction ratio for rotation by upward passage of light through the coverglass is now reduced from 6:5 to the almost negligible value 21:20. There is a corresponding improvement in the homogeneity of extinction over the microscope field.
Olivine composition determination with small-diameter X-ray powder cameras
Authors: Jambor J. L. , Smith Charles H.
Published: December 2006

Olivine composition can be rapidly and accurately obtained by using standard (Straumanis-mounting) 57·3 mm X-ray powder cameras. A determinative curve based on analysed natural olivines has been constructed by plotting the mol. % Fo against the spacing of back-reflection line 174. The regression equation for the composition range Fo100 to Fo30 is

Fo (mol. %) = 4151·46−3976·45 d174

using Fe-Kα1 radiation. The fayalite end (Fo30 to Fo0) of the determinative curve shows a relatively sharp break from a straight-line relationship of d-spacing versus composition. Practical applications of the determinative curve are briefly presented.
Statistical analysis of X-ray data for olivine
Authors: Agterberg F. P.
Published: December 2006

A diagram of the relationship between d174 and % forsterite in olivines is presented in fig. 1 of the preceding paper by Jambor and Smith. In this note, statistical aspects of Jambor and Smith's data are considered in detail and compared to equivalent data by Yoder and Sahama (1957). This analysis leads to the conclusion that the relationship of mol. % Fo and d174 or d130 can be expressed as a straight line for Fo > 30 %. Olivines with Fo < 10 % are not related to this straight line.
A siereographic construction .for determining the optic axes of a biaxial crystal directly ,from a few extinction measurements
Authors: Joel N.
Published: December 2006

It is possible to determine the directions of the optic axes of a biaxial crystal mounted on a spindle stage—and hence the angle 2V and the directions of α, β, γ—from only four measured extinction positions. The method is a generalization of the one proposed by Tocher (1962); but in the present procedure it is not necessary to determine first the optic axial plane.
Reyerite
Authors: Chalmers R. A. , Farmer V. C. , Harker R. I. , Kelly S. , Taylor H. F. W.
Published: December 2006

Reyerite from the original locality in Greenland has been re-examined using chemical analysis, infra-red absorption, X-ray powder and single-crystal diffraction, and thermal weight-loss curves. The unit cell is trigonal with a 9·74, c 19·04 Å, and the space group is probably P3¯. The unit cell contents are probably best represented as KCa14(Si24O60)(OH)5.5H2O, with some minor replacements. The molecular water is lost reversibly below 400° C. There are indications that the crystal structure is based on Si6O18 rings resembling those in beryl, but linked into sheets by additional tetrahedra.

Reyerite closely resembles truscottite, a mineral found originally in Sumatra, but there are distinct differences, especially in the infra-red pattern. It is not yet certain whether or not the two minerals should be considered as distinct species. Synthetic preparations examined resembled truscottite more closely than reyerite.
Spurrite from northern Coahuila, Mexico
Authors: Temple A. K. , Heinrich E. Wm.
Published: December 2006

Spurrite-bearing contact-metasomatic mineral assemblages occur with a few of the many rhyolite stocks intrusive into Georgetown (Cretaceous) limestone in the Encantada district of northern Coahuila, Mexico. The contact-metasomatic suites are found associated only with rhyolites that solidified within the thick Georgetown limestone. Rhyolites that penetrated through the limestone have sharp contacts commonly marked by perlitic contact breccias. The structural form of all the rhyolites indicates intrusion under high pressure.

Three distinct contact-mineral suites have been recognized: Foliated garnetwollastonite rocks occur adjacent to the rhyolite, whereas spurrite is only found further from the intrusive. The inner side of the spurrite-bearing zone is characterized by foliated spurrite-garnet-periclase rocks, whereas the outer side of the spurrite zone consists of a massive, coarse-grained, spurrite-rankinite-periclase rock, which has a sharp contact with the outermost foliated marble zone. At one location, massive spurrite occupies ‘dikes’ radial to the intrusive, which are post-dated by wollastonite-bearing gehlenite-diopside rocks.

It is concluded that the stages of rhyolite emplacement include: First, preliminary high-pressure structural site preparation accompanied by intrusion of rhyolite and metasomatic introduction of Si and Al into preheated cap rock. Then crystallization of the metasomatic zone, under conditions of upward pressure exerted by the rhyolite, to give the features of the spurrite zone; followed by conversion of the inner side of the spurrite zone to a wollastonite-bearing assemblage.
Conical extinction curves: a new universal stage technique
Authors: Joel N. , Tocher F. E.
Published: December 2006

New generalized extinction curves, derived from wave-normals located on a circular cone, are presented. They may be used with the universal stage for the accurate location of up to all three of the indicatrix axes, α, β, γ, of any biaxial crystal, or the optic axis of any uniaxial crystal.
Epidotes of the Borrowdale Volcanic rocks of central Borrowdale
Authors: Strens R. G. J.
Published: December 2006

Epidote and clinozoisite are widely distributed in the andesitic lavas and tuffs of the Borrowdale Volcanic Series. Four main types of occurrence may be distinguished, namely quartz-epidote vein fillings; ‘Shap type’ veins, bordered by pink reaction zones rich in SiO2, Na2O, and K2O; autometasomatized lavas and tuffs; and tuffs subjected to alkali metasomatism. Epidote alone formed in the quartz-epidote veins; clinozoisite is found with epidote in the other types of occurrence.

Epidote and clinozoisite formed in vesicles at pressures of 10–280 kg/cm2, at temperatures of 300–550° C; epidote associated with pre-Bala mineral veins formed in the range 130–550° C at 1000 kg/cm2; epidote around the Caledonian granites probably formed up to 600° C at about 2000 kg/cm2. Clinozoisite crystallized together with epidote in the vesicles, demonstrating a gap in the clinozoisite-epidote solid solution series. Early formed epidote in vesicles is more strongly coloured than late epidote, although the compositions of the earliest and latest fractions are identical.
A petrographic and geochemical study of back-veining and hybridization at a gabbro-felsite contact in Coire Dubh, Rhum, Inverness-shire
Authors: Dunham A. C.
Published: December 2006

Field, petrographic, and chemical data are presented which make it possible to follow the course of back-veining of felsite by a gabbro ring-dyke. The remelted felsite back-veined the chilled margin of the gabbro, then acidified the partly crystalline basic mush within the chilled zone and finally mixed with the mainly liquid basic magma farther inside the dyke to produce hybrids of marscoitic aspect. Spectrographically determined trace-element data, with data on some major elements, illustrate these changes. The veins are shown to have a composition nearer the ternary minimum in the system Ab-Or-Qz-H2O than the parent felsite, while culminations of soda and iron in the acidified gabbros and hybrids suggest that metasomatism has accompanied the mixing of the partly liquid end members. This study confirms the earlier suggestion that the gabbro post-dates the felsite.
Amphiboles in alkaline rocks of Koraput, Orissa
Authors: Bose Mihir Kumar
Published: December 2006

The chemistry and optics of the amphiboles in alkaline rocks of Koraput, Orissa, India, are described. The variation in chemical characters of the amphiboles is consistent with the variation in rock composition. With progressive fractionation the mineral shows increasing replacement of magnesium by iron while Ca is not affected by such replacement. The trend in variation is comparable to that in pyroxenes of alkaline basaltic magmas. The entry of Ti into the structure of amphibole appears to be favoured by alumina activity and concentration of Ti in the magma. Optical characters vary with the iron : magnesium ratio and titanium content of the mineral. The water content of the magma had an important influence on the composition of the mafic minerals in the rocks.
Wairauite—a new cobalt-iron mineral
Authors: Challis G. A. , Long J. V. P.
Published: December 2006

A new cobalt-iron mineral of composition close to CoFe has been found associated with awaruite (Ni3Fe) in the Red Hills serpentinites of the Wairau Valley, South Island, New Zealand. The name wairauite, after this locality, is proposed. Electron-probe analysis of the small grains so far discovered has shown that the nickel content is very low (0·5 ± 0·1 wt. %). Wairauite is optically very similar to awaruite but a tendency to form euhedral grains (octahedron and cube) and a slightly lower refiectivity are an aid to identification. No X-ray data are available at present, but it is suggested that the structure may correspond to that of the ordered CsCl type of the synthetic alloy of the same composition.
A study of the hydrothermal growth of ruby
Authors: Butcher J. , White E. A. D.
Published: December 2006

Experiments have been conducted to determine the optimum conditions for the hydrothermal growth of ruby. The solubility of corundmn in various solutions has been determined and compared with the respective growth obtained in each medium. The discrepancy between solubility and effective growth is discussed.

The need for a high degree of chemical purity has resulted in the development of platinum liners for the autoclaves. The effects of impurities and of other factors on the growth of ruby crystals have been studied. The crystal habit of hydrothermal ruby is also described.