bluuebunny/crossref_metadata_2025 huggingface dataset:
Stability of Al2SiO5 solid solutions
Authors: Strens R. G. J.
Published: December 2006

An ideal solution model has been used to calculate the effect of the substitutions on the stability fields of the Al2SiO5 minerals. The results show that divariant assemblages of andalusite+sillimanite and sillimanite + kyanite solid solutions can coexist over ranges of 0·1 to 0·4 kbar at 527° C, but that kyanite+andalusite would be stable over a much narrower range. On adding (Fe, Mn)3+ to the system, the andalusite/sillimanite curve can be considered to rotate about the invariant point, first eliminating the sillimanite field, and then penetrating the kyanite field. Wide zones of viridine+sillimanite and viridine+kyanite are thus formed.

In view of the ease with which epitaxial nucleation occurs in the Al2SiO5 system, it is considered that extensive metastable growth of andalusite, sillimanite, and kyanite is improbable in nature. Metastable persistence is likely to occur in dry systems, or in the presence of an ‘armour’ of the stable phase, but reaction of millimetre-sized crystals should be completed in geologically short times when aqueous or silicate liquids are present. The combination of the effects of metastable persistence and solid solution seems adequate to account for essentially all the examples of kyanite + sillimanite and kyanite + andalusite, and for many sillimanite +andalusite assemblages. In addition, if small supersaturations develop during metamorphism, simultaneous growth of andalusite + sillimanite could occur over a restricted temperature range.
Copper in various phases of several olivine-hypersthene and olivine-bronzite chondrites
Authors: Hey M. H. , Easton A. J.
Published: December 2006

Determinations of Cu in separate phases of three olivine-hypersthene and one olivine-bronzite chondrites show that it is very strongly concentrated in the taenite; appreciable amounts are present in the olivine, less in the pyroxene plus plagioclase; it is probable that the copper found in the ‘unattracted, attacked’ fraction is present as metallic copper, and that very little is present in the sulphides.
Electronprobe analyses of stannite and related tin minerals
Authors: Springer G.
Published: December 2006

Quantitative electronprobe microanalyses have been made of stannite from various localities. It was found that in general this mineral corresponds in composition to the formula Cu2FeSnS4. However, noticeable deviations in the ratio of the metals can occur and considerable concentrations of zinc may be present.

Some tin minerals related to stannite have also been analysed, namely hexastannite, mawsonite, and an apparently hitherto unknown mineral to which the name rhodostannite is given.
A former association of enstatite and kyanite
Authors: Chinner G. A. , Sweatman T. R.
Published: December 2006

An enstatite-cordierite-sillimanite-quartz rock from a pyroxenegranulite facies terrain in southern Rhodesia gives evidence of at least two stages of recrystallization : an early, high-pressure recrystallization to form the assemblage enstatite-kyanite-quartz, and a later, ‘retrogressive’ recrystallization during which kyanite inverted to sillimanite, and cordierite was formed by reaction. The rock itself has ratios of R2+ : Al : Si that are virtually those of cordierite ; the recent data of Schreyer (1967) may thus be applied to the occurrence. The early kyanite-enstatite recrystallization occurred under pressures in excess of 10 kb, corresponding to depths greater than those of the continental Moho.
Chemical variation in tourmalines from South-west England
Authors: Power G. M.
Published: December 2006

Forty-eight samples of tourmaline from the granitic rocks of south-west England have been analysed by emission spectrography for Fe, Mn, Mg, Ca, Ti, Na, F, Li, Sc, V, Cr, Co, Ni, Cu, Ga, Rb, Sr, Zr, Sn, and Sc. The tourmaline reflects the fractionation trends of the rocks from which it comes in the proportion of Mg, Ca, Ti, and certain trace elements it contains and is considered likely to have been a primary product of the magma. Textural evidence that indicates a later development is interpreted as recrystallization, possibly at low temperature, with little change in chemical composition. Hydrothermal tourmaline has a distinctive chemical composition, being higher in Mg, Ca, Sr, and Sn and lower in Fe, Mn, and F and also tending to have a higher Cr, V, Ni, and Sc content. The chemical composition of the tourmalines is used to show that some quartz-tourmaline rocks are the product of extreme fractionation and are not completely tourmalinized granites. Parti-coloured tourmaline is shown to be the result of hydrothermal growth.
The stability of tobermorite in the system CaO-SiO2-H2O at elevated temperatures and pressures
Authors: Speakman K.
Published: December 2006

Hydrothermal studies in the silica-rich region of the CaO-SiO2-H2O system have given information on the stability field of tobermorite. At saturated steam pressures tobermorite is unstable relative to xonotlite (C6S6H) above 140 °C but between 10 000 and 40 000 lb/in.2 (69 and 276 N/mm2), the decomposition temperature is raised to 285±5 °C. Tobermorite is stable at all compositions between C/S = 0·67 and 1·0 up to this temperature and has a formula close to C5S6H5. Variable compositions reported earlier are thought to be mixtures rather than lime-rich or silica-rich tobermorites.

Data have also been collected on the equilibrium assemblages below C/S = 0·67 and between C/S = 1·0 and 1·5 involving truscottite, gyrolite, xonotlite, foshagite, and hillebrandite.
Colour in charnockites
Authors: Oliver R. L. , Schultz P. K.
Published: December 2006

Microprobe analysis of leached and unleached varieties of a charnockitic rock from Madras supports the contention of Howie (1964) that the characteristic dark greenish colour of such rocks is contained mainly in fine (chloritic ?) veinlets cutting the feldspar and quartz, though a certain amount appears to be contained in exsolved sodium feldspar. Leaching of the darkish colour of the charnockitic rock has not affected the crystallographic state of the potassium feldspar.
The related layered minerals ganophyllite, bannisterite, and stilpnomelane
Authors: Smith Marie Lindberg , Frondel Clifford
Published: December 2006

Two monoclinic minerals formerly classified as ganophyllite have been differentiated on the basis of single-crystal X-ray data. True ganophyllite occurs at the Harstig mine, Pajsberg, Sweden (a, 16·60 ± 0·05 Å;b, 27·04 ± 0·08 Å;c, 50·34 ± 0·15 Å;β, 94° 10′ ± 10′; space groupA2/a), at the Benallt mine, Caernarvonshire, Wales, and in Aroostook County, Maine. Bannisterite, a new mineral, occurs at Franklin, New Jersey (a, 22·20 ± 0·07 Å;b, 16·32 ± 0·05 Å;c, 24·70 ± 0·08 Å;β, 94° 20′ ± 10′; space groupA2/a) and at the Benallt mine, Wales. Both minerals have similar pseudocells:a, 5·53 Å;b, 3·3 Å;c, 25 Å;β, 94° The chemical analysis of ganophyllite from the Harstig mine, Sweden, is: SiO2, 39·67 %; Al2O3, 7·95; Fe2O3, 0·90; MnO, 35·15; CaO, 1·11; MgO, 0·20; PbO, 0·20; K2O, 2·70; Na2O, 2·18; Li2O, trace; H2O, 9·79; total, 99·85. The chemical analysis of bannisterite from Franklin Furnace, New Jersey, is: SiO246·20 %; Al2O3, 4·74; MnO, 23·02; FeO, 6·40; ZnO, 4·67; CaO, 1·52; MgO, 1·99; Na2O, 0·29; K2O, 1·21; H2O, 9·74; total, 99·78.

Both ganophyllite and bannisterite show a structural resemblance to stilpnome-lane from Deer Isle, Maine, in projection on selected zones. All three have a micaceous cleavage parallel to {001} in the orientations here taken. Stilpnomelane is triclinic, pseudotrigonal, and pseudomonoclinic. In the triclinic cell,a=b, 22·05 Å ± 0·06 Å;c, 17·70 ±0·06;α, 124° 49′;β, 95° 58′;γ, 120° 00′ (angles ± 5′). In the trigonal subcell,a′, 3·2 Å;c′, 36·4. Small distorted trigonal subcells for ganophyllite havea′, 3·38 Å;c′37·7, and for bannisterite havea′, 3·264 andc′, 37 Å.
The mineralogy of the potassium-barium feldspar series III: Subsolidus relationships
Authors: Gay P. , Roy N. N.
Published: December 2006

Further data are presented on the properties of natural and synthetic members of this series. Cell constants have been determined for over 50 specimens across the composition range; the activation energy for a low-high transformation in an intermediate hyalophane has been evaluated as 101·5 ± 5·0 kcal/mole; additional single crystal studies have revealed complexities not previously reported.

Although there remain many detailed problems to be resolved, the present studies allow some suggestions concerning the nature of the relationships within the series. Problems of nomenclature and subsolidus relations are discussed together with some structural implications.
Synthesis and study of diaboleïte
Authors: Winchell R. E. , Wenden H. E.
Published: December 2006

Diaboleïte has been synthesized between 25 and 100° C at atmospheric pressure and approximate water vapour partial pressures of 14·7 lb/in2. Under similar conditions at 170° C cumengéite appears to be the stable phase produced from a diaboleïte composition. Synthetic diaboleïte is much simpler morphologically than the natural mineral but the hemimorphic symmetry is more clearly demonstrated morphologically in the artificial specimens. A comparison of X-ray powder data for natural and synthetic diaboleïte shows almost exact detailed correspondence in line position and intensity between 0 and 180° 2θ. The cell dimensions obtained from X-ray powder data are a 5·869 ± 0·002 Å and c 5·495 ± 0·003 Å.
The crystal structure of gersdorffite (III), a distorted and disordered pyrite structure
Authors: Bayliss P. , Stephenson N. C.
Published: December 2006

The crystal structure of gersdorffite (III) has been examined with three-dimensional Weissenberg X-ray diffraction data. The unit cell is isometric with a 5·6849 ± 0·0003 Å, space group PI, and four formula units per cell. This structure has the sulphur and arsenic atoms equally distributed over the non-metal atom sites of pyrite. All atoms show significant random displacements from the ideal pyrite positions to produce triclinic symmetry, which serves to distinguish this mineral from a disordered cubic gersdorffite (II) and a partially ordered cubic gersdorffite (I). Factors responsible for the atomic distortions are discussed.
Ferrian chlorospinel from Carneal, Co. Antrim
Authors: Sabine P. A. , Sergeant G. A. , Young B. R.
Published: December 2006

A Tertiary dolerite plug at Carneal, Co. Antrim has been contaminated by Chalk with the production of calc-silicates and related minerals. In a larnite-spinel-rock the spinel is of the unusual ferrian variety. It has the composition The spinel, which is brown, has: n, 1·862; D, 3·97; a, 8·1905 Å. A chemical analysis and powder data are given, the implications of experimental data are briefly discussed, and the nomenclature is reviewed.
The mineralogical characteristics of calcium-iron olivines
Authors: Wyderko Marta , Mazanek Eugeniusz
Published: December 2006

For the estimation of the properties of calcium-iron olivines in ironore sinters, synthetic mixtures of CaO, FeO, and SiO2 were prepared and melted; the obtained olivines were then examined microscopically and by X-ray powder method. The investigations allowed to state, that with the increase of the basicity of sinters, the relation of Fe : Ca in olivines decreases, which causes the change of their physical, optical, and röntgenometric properties.
Oriented transformations in the system MnO-O-H2O
Authors: Dent Glasser Lesley S. , Smith Ian B.
Published: December 2006

Extensive studies on oriented reactions in the system MnO-O-H2O have revealed surprising symmetry changes, which we have been unable to explain. Orientation relationships are often complicated, but where interpretation is possible, the results support the idea that orientations are controlled by the oxygen frame-work and that considerable migration of manganese occurs.
Subsolidus phase relations in the system ZnWO4-ZnMoO4-MnWO4-MnMoO4
Authors: Chang Luke L. Y.
Published: December 2006

Subsolidus phase relations in the systems ZnWO4-MnWO4, ZnWO4-ZnMoO4, MnMoO4-ZnMoO4, and MnWO4-MnMoO4, were investigated by using the quenching technique. A complete series of solid solutions forms in the system ZnWO4-MnWO4 above 840° C, whereas limited solid solubilities were found in the other three. The various limits of solubility are, at 620° C, 4·0 mole % ZnMoO4 in ZnWO4 and 4·0 mole % ZnWO4 in ZnMoO4, 13·0 mole % ZnMoO4 in MnMoO4 and 12·0 mole % MnMoO4 in ZnMoO4, 9·0 mole % MnMoO4 in MnWO4 and 6·0 mole % in MnWO4 in MnMoO4; and at 1000° C, 15·0 mole % ZnMoO4 in ZnWO4 and 15·0 mole % ZnWO4 in ZnMoO4, 36·0 mole % ZnMoO4 in MnMoO4 and 29·0 mole % MnMoO4 in ZnMoO4, 15·0 mole % MnMoO4 in MnWO4 and 27·0 mole % MnWO4 in MnMoO4.

Subsolidus phase relations in the system ZnWO4-ZnMoO4-MnWO4-MnMoO4 were studied at 900° C. The solubility of molybdenum in the (Zn,Mn)WO4 series increases from both end members to a maximum of 27·0 mole % at the composition Mn35Zn65. Both molybdates also have limited ranges of solid solutions, and a three-phase region occupies the central portion of the system defined by three points with compositions of 41 mole % ZnMoO4, 26 mole % MnMoO4, 33 mole % MnWO4; 57 mole % ZnMoO4, 10 mole % MnMoO4, 35 mole % MnWO4; and 27 mole % ZnMoO4, 34 mole % MnWO4, 39 mole % ZnWO4.
On the infra-red spectrum and thermal decomposition products of thaumasite, Ca3H2(CO3/SO4)SiO4.13H2O
Authors: Kirov G. N. , Poulieff C. N.
Published: December 2006

The infra-red spectrum of untreated thaumasite Ca3H2(CO3/SO4)SiO4.13H2O, as well as the spectra and X-ray diffraction patterns of thaumasite heated in air at 200, 360, 550, 725, 800, 900, and 1150° C were investigated. The release of CO2 and H2O upon heating was followed. It was established that thaumasite changes between 200 and 550° C to a glass-like, amorphous state. Ca2SiO4-polymorphs and anhydrite are formed upon heating at temperatures up to 800° C. From 900° C calcium silicosulphate and anhydrite are the thermal decomposition products. These results are used in the assignment of the IR-absorption bands under 1400 cm−1 of untreated thaumasite, which are shown to be of a composite nature, i.e. attributable to overlapping vibrations of both sulphate and silicate tetrahedra.
Oligoclase-andesine phenocrysts and related inclusions in basalts from part of the Nigerian Cenozoic province
Authors: Wright J. B.
Published: December 2006

The Benue trough is a graben structure containing folded Upper Cretaceous sediments. Mid-Tertiary to Recent rift-valley type vulcanicity in and near the trough was mainly basaltic (in the north at least), salic lavas being now represented mainly by a few eroded plugs. The Nigerian rocks are regarded as a practically extinct sub-province within a larger Gulf of Guinea alkaline province, dominated by the voluminous and still active vulcanicity of the Cameroun rift. The two structures have the same trend as other graben features further south along Africa's western margin.

Large sodic plagioclase crystals in a basalt plug within the Nigerian sub-province have rounded edges and more calcic overgrowths. They probably crystallized at deep crustal levels but are unaccompanied by any of the mafic phases that normally crystallize from basalts under high pressure. However, spinel crystals and olivine nodules found in a nearby plug indicate that the complementary mafic assemblage may be found not far away. Sparse published data on phenocrysts and inclusions in the Jos Plateau lavas offer some support for this suggestion.

Crystallization of sodic feldspars in basalt may have a bearing on the independent genesis of salic liquids, while apatite and magnetite inclusions in them suggest a possible link with carbonatites.
The variation of the 01 reflection in plagioclases
Authors: Hamilton D. L. , Edgar A. D.
Published: December 2006

The position of the 01 X-ray reflection in albite varies with the degree of Al/Si ordering. This is also true for binary plagioclases but the 01 reflection for high-temperature plagioclases is constant and therefore independent of anorthite content. For plagioclases of ternary composition grown in a hydrous silicate melt, the position of the 01 reflection gives a good estimate of the orthoclase content when a determinative curve is used that was originally drawn from data on high-temperature synthetic binary alkali feldspars.
X-ray data, optical anisotropism, and thermal stability of cobaltite, gersdorffite, and ullmannite
Authors: Bayliss P.
Published: December 2006

Data are presented from cobaltite (CoAsS), gersdorffite (NiAsS), and ullmannite (NiSbS) for cell size, compositional zoning, mineralogical association, X-ray diffraction powder intensities, and optical anisotropy. The presence of powder X-ray diffraction reflections 001 and 011 are related to the crystal structure type. The amount of distortion from cubic symmetry is related to the 001 reflection intensity and also to the optical anisotropism strength. These properties are related approximately to the thermal stability of the distorted crystal structure. This thermal stability increases with the substitution of cobalt for nickel, which decreases the cell size. An order-disorder change occurs before the distortion release in non-cubic gersdorffite (P1) with a large cell size, whereas only a distortion release is observed in cobaltite (Pca21) and non-cubic gersdorffite (P1) with a small cell size. Glaucodot (Co,Fe)AsS converted to cobaltite at 620 C. No evidence was found to relate optical anisotropism of pyrite to deviations from cubic symmetry.
The Siena meteorite: Mineralogy and Chemistry
Authors: Baldanza B. , Levi-Donati G. R. , Wiik H. B.
Published: December 2006

The principal data are collected about the fall and the distribution of the fragments of the Siena, Italy, meteorite (11·6°E., 43·1°N.). A complete individual, weighing 110·55 g, is described in some detail. Crust morphology, mineralogical composition, and structure were studied. Optical data were established by microscopical analysis and both thin and polished sections were observed. Compared with available electron-probe analysis they are found in good agreement. The chemical analysis is Fe 12·93, Ni 1·39, Co 0·09, FeS 5·46, SiO2 37·10, TiO2 0·14, Al2O3, 3·91 FeO 11·46, MnO 0·35, MgO 23·81, CaO 1·63, Na2O 0·90, K2O 0·16, P2O5 0·44, H2O+ 0·10, H2O− 0·00, Cr2O3 0·56, total 100·43. Siena is an ordinary chondrite, with relatively ambiguous characteristics and evident features of recrystallization and metamorphism.
The determination of multiple correlations between several variables, with especial reference to the correlation of physical properties and chemical composition
Authors: Hey M. H.
Published: December 2006

If the true values of a number (n) of variables are exactly related by one or more (m) equations but all experimental values are liable to experimental error then, provided the errors of measurement can be assumed to be symmetrically distributed about a zero mean, provided the relations are linear, and provided the assessed probable errors of measurement of the several variables remain in constant ratio from one set of measurements to another, the best estimate of the relations derived fromNsets of measurements will be given by the latent vectors corresponding to themsmallest latent roots of then-square matrix whose terms are Σwiξijξik(summed from (summed fromi= 1 toi=N) for alljandkfrom 1 ton, wherewiis the weight of theith set of measurements and ξijis the standardized value of theith measurement of thejth variable measured from its weighted mean.

It is also shown that the alleged inconsistency of the maximum-likelihood estimate of the variance in such a case is simply a confusion of the root-mean-square residual with the root-mean-square normal residual.

An Autocode computer programme has been written to carry out the necessary operations for correlating the physical properties and chemical properties of an isomorphous series of minerals using this procedure.
Study of minerals from the pegmatites of the Nellore mica-belt, Andhra Pradesh, India Part I. Microcline perthites
Authors: Babu V. R. R. M.
Published: December 2006

The obliquity values of microcline perthites are nearer to maximum microcline type, indicating that they have less than 10% Ab in their lattices, apart from exsolved albite. The perthites are classified based on form as stringlet, string, film, vein, and replacement types. It is concluded that stringlet and string perthites are formed by exsolution along contraction cracks, followed by film as a result of decrease in rate of cooling and increase in water vapour content of the pegmatites, whereas vein and replacement perthites are formed last, by replacement when the pegmatites crystallized in a closed system. Based on the chemical composition of microcline perthites, a temperature of 600 °C is arrived at for unmixing of feldspar to give rise to microcline perthite.
Study of minerals from the pegmatites of the Nellore mica-belt, Andhra Pradesh, India Part II. Muscovite
Authors: Babu V. R. R. M.
Published: December 2006

The muscovites are 2M1 polymorph type; minimum temperature of crystallization of 435 °C is obtained from the molecular percentage of paragonite in muscovite.
Localization and distribution of impurities in blende by cathodoluminescence
Authors: Goni J. , Rémond G.
Published: December 2006

Cathodoluminescence, produced by electronic bombardment in the microprobe, can serve to indicate the nature and distribution of elements present in amounts below the normal detection limit of the probe. This is illustrated by a study of specimens of blende from various localities.
Electrostatic energy for ion clustering in intermediate plagioclase feldspar
Authors: Smyth Joseph R. , Smith Joseph V.
Published: December 2006

Electrostatic calculations estimated the energy of hypothetical ion clustering in intermediate plagioclase feldspars. The calculated energy appears too great to allow segregation of Ca and Na atoms into domains upon annealing without a corresponding movement of Al and Si from an original disordered structure. The calculated energy may be sufficiently small that Ca and Na atoms can disorder partially without movement of Al and Si upon heating a low-plagioclase to high temperatures.
Kaersutite-bearing plutonic xenoliths from Tristan da Cunha, South Atlantic
Authors: Le Maitre R. W.
Published: December 2006

The xenoliths, which are gabbroic in character, consist of kaersutite, titanaugite, plagioclase, and iron ore in variable amounts. Biotite and olivine are also occasionally present. New analyses and trace element data are given for two xenoliths and their coexisting kaersutite, titanaugite, and plagioclase. After discussing several possible origins with the aid of a principal latent vector variation diagram, it is concluded that they represent the accumulation of phases that crystallized from the Tristan magma at depths between 5 and 25 km. Evidence is also presented to show that the parental Tristan magma may be of trachybasalt composition.
A Mössbauer study of biotite weathering
Authors: Rice C. M. , Williams J. M.
Published: December 2006

Fresh and weathered biotites have been studied using Mössbauer, chemical, and X-ray analytical techniques. In the Mössbauer spectra the complete interference of both low-spin ferric lines by one of the high-spin ferrous lines and the existence of high-spin ferric iron in the weathered biotite has been demonstrated. In view of this interference, which appears to be common, allowances must be made in spectral interpretation if chemical analysis reveals ferric iron to be present in detectable amounts. Hypothetical extension of the weathering trends observed suggests that high-spin ferric iron is the only stable iron species in the end product.

During weathering marked loss of ferrous iron occurs, whereas the ferric iron content remains approximately constant. As a result of the instability of ferrous iron in the weathering environment there is a significant rearrangement of the octahedral layer.
Petrofabric analysis of a large microporphyritic chondrule in the Parnallee meteorite
Authors: Dodd R. T.
Published: December 2006

Olivine microphenocrysts in a large microporphyritic chondrule in the Parnallee chondrite show a linear preferred orientation of the long (β = c) axes, which is thought to reflect flowage of a partly crystalline parent magma. The orientation pattern is somewhat disturbed by post-crystallization fracturing.
A chromian hydrogrossular from Jordanów, Lower Silesia, Poland
Authors: Heflik W. , Żabiński W.
Published: December 2006

A new variety of garnet, a chromian hydrogrossular, has been found in a loose block of diopside-albite rock in a quarry of serpentinite in Jordanów, Lower Silesia. Its chemical formula is given. Although the water content of this garnet barely exceeds 1 %, the X-ray, thermal, infra-red spectrophotometric, and optical examinations give evidence that this water, in the form of (OH)4 groupings, substitutes for the SiO4 tetrahedra. The chromian hydrogrossular from Jordanów belongs to the numerous calcium-rich silicates that were formed there during the process of alteration of serpentinites by lime-rich hydrothermal solutions.
Synthesis of aenigmatite
Authors: Thompson R. N. , Chisholm J. E.
Published: December 2006

Aenigmatite with the formula Na4[Fe102+Ti2]Si12O14 has been synthesized hydrothermally, at 700 °C and 1000 bars PH2O, from an oxide starting material. The oxygen fugacity was controlled by means of an iron-wüstite buffer. An indexed X-ray powder pattern of synthetic aenigmatite is given, together with comparative data on two natural samples. One of the aenigmatites, from Kola, U.S.S.R., is known to be triclinic (Kelsey and McKie, 1964). The powder patterns of this and the synthetic aenigmatite are so similar that it is concluded that the latter is also triclinic, at least at room temperature.
Mesonorms of granitic rock analyses
Authors: Parslow G. R.
Published: December 2006

A modification to the CIPW norm, to account for the presence of biotite or muscovite or both in granite rocks, is described. The modification is most significant in norms that have been reduced to three components and plotted on experimental phase diagrams, such as the systems Q-Or-Ab and Or-Ab-An.
X-ray powder data for idoerase
Authors: Domańska E. , Nedoma J. , Żabiński W.
Published: December 2006

An X-ray powder pattern of idocrase (vesuvianite) from Canzoccoli, Italy, has been indexed by the method described by Nedoma (1968a, b). The improved X-ray data collected in the paper can be useful in identifying this mineral and in discussing the influence of diadochic substitutions on the lattice parameters of idocrase.
Crichtonite, a distinct species
Authors: Hey M. H. , Embrey P. G. , Fejer E. E.
Published: December 2006

Confusion over the status of crichtonite is due to the fact that de Bournon included two different minerals in his species: thin hexagonal plates are indeed ilmenite, as has been generally assumed, but the much rarer steep rhombohedra with basal plane are a separate species, with a distinctive X-ray powder pattern (three strongest lines: 3·39 Å,s; 2·875,s; 2·131,S) and a composition (Fe2+,Fe3+,Ti)1·71O3 with Fe2+:Fe3+:Ti near 8:7:33. There is a rhombohedral pseudo-cell containing three oxygens, with α 23° 19′, a 7·117 Å but there is some evidence of twinning, and the true symmetry is probably orthorhombic or lower.
Water in sphere-type opal
Authors: Jones J. B. , Segnit E. R.
Published: December 2006

Surface areas of ‘amorphous’-type opals measured by nitrogen-absorption techniques were not consistent either with the surface area of the spheres of about 2000 Å diameter observable by electron microscopy or with the thermal dehydration data. This apparent inconsistency can be explained in terms of a smaller particulate structure of the order of 100–200 Å shown by higher resolution electron micrographs. This structure also accounts for a marked shrinkage shown in dilatometer curves of this type of opal.
Olivine nodules and related inclusions in trachyte from the Jos Plateau, Nigeria
Authors: Wright J. B.
Published: December 2006

A trachyte plug near Jos contains a suite of inclusions, commonly rounded and of large size, including olivine nodules, pyroxenites, and a variety of basic to intermediate plutonic rocks, as well as albite megacrysts.

The olivine nodules are typical of those found elsewhere in alkaline basic lavas and widely interpreted as upper mantle fragments. Most of the other inclusions contain evidence of crystallization at high pressures, even the syenites, which are interpreted as plutonic equivalents of the trachyte; for the feldspar in them is sanidine-microperthite.

Discovery of this inclusion assemblage in a trachyte provides further support for the thesis that alkaline salic lavas can be generated at sub-crustal depths, by partial melting beneath domically uplifted continental shield areas (Bailey, 1964).

The Nigerian Cenozoic volcanic province lies in an area of regional uplift, and is characterized by scattered small volcanic centres rather than by major eruptive foci. High pressure inclusions are being found at an increasing proportion of these centres, suggesting that the magmas rose directly and rapidly to the surface from the upper mantle levels at which they were all (including the trachyte) generated.
Olivine, pyroxene, feldspar, and spinel in ultramafic nodules from Auckland, New Zealand
Authors: Rodgers K. A. , Brothers R. N.
Published: December 2006

Chemical, optical, and X-ray data are presented for forsteritic olivine, bronzite-enstatite, diopsidic augite, anorthite, and spinel from ultramafic nodules at seven localities in Auckland province. Olivine has a composition range from Fo79–93for large primary crystals to Fo80–100for smaller interstitial grains. Orthopyroxenes (En83–96) carry exsolution lamellae of clinopyroxene parallel to (100); clinopyroxenes are mainly diopsidic augites with exsolved bronzite. The plagioclase (An97) has high-temperature characteristics and a lattice structure probably transitional between primitive and body-centred anorthite. Spinels include chromite, picotite, ceylonite, hercynite, and magnetite. Element distribution indicates that the ultramafic assemblages attained equilibrium at temperatures near 1250 °C and at moderate pressures, corresponding to the melting interval of anhydrous basaltic magmas within the uppermost mantle.
The mineralogy of Egyptian serpentinites and talc-earbonates
Authors: Basta E. Z. , Abdel Kader Z.
Published: December 2006

Optical, d.t.a., X-ray, and chemical analysis investigations were carried out on serpenttinites from various Egyptian localities and on their associated talc-carbonates. The serpentinites were proved to consist of pure antigorite, lizardite, or clinochrysotile, or of mixtures of any pair of these serpentine minerals. Lizardite, which is reported for the first time in Egypt, is found to be of common occurrence. Talc, tremolite, carbonates, chlorite, olivine, biotite, chromite, magnetite, goethite, and stevensite are the main admixtures. The talc-carbonates consist mainly of talc and magnesite, or magnesite, dolomite, and talc together with minor amounts of antigorite, magnetite, goethite, and occasionally a little chlorite or calcite. Spectrographic analyses of some of the magnetically separated serpentines have been carried out and the origin of the Egyptian serpentinites and talc-carbonates is briefly discussed.
The preparation of fused samples in X-ray fluorescence analysis
Authors: Hooper P. R. , Atkins Lynne
Published: December 2006

A rapid fusion technique is described in which the Li2B4O7 bead is polished, not crushed. The reliability of the technique is illustrated by a series of precision tests and analyses of standard rocks, using a 2:1 Li2B4O7 : rock-powder dilution. It is also pointed out that such a low-dilution fusion method may be used for Na2O and trace element analyses with only a small loss in sensitivity relative to the unfused-powder method. Any fusion method has the advantages of greatly reducing absorption effects and eliminating particle-size effects.
Dadsonite (minerals Q and QM), a new lead sulphantimonide
Authors: Jambor J. L.
Published: December 2006

Dadsonite was previously described without a name: (mineral Q) from Yellowknife, N.W.T.; (mineral QM) from Madoc, Ontario, and Pershing County, Nevada. Material from a fourth locality (Wolfsberg, Germany) yields good powder patterns, identical with those of QM, and single crystal data identical with those for Q.

Microprobe analysis of the Nevada and Wolfsberg samples gave, respectively, Pb 49·3, 50·8; Sb 31·7, 31·8; S 20·7, 20·3; sum 101·7, 102·9 %, giving Pb11Sb12·0S29·8 and Pb11Sb11·7S28·4, ideally Pb11Sb12S29 or 11PbS·6Sb2S3. Dadsonite is acicular [010], monoclinic, space group P2, Pm, or P2/m, with a 19·05, b 4·11, c 17·33 Å, β 96° 20′, Z = 1, Sp. gr. 5·76. The strongest lines of the X-ray pattern are 3·78 (7), 3·62 (6), 3·38 (10), 2·84 (7), and 2·79 Å (6).
Sulphosahs of the plagionite group
Authors: Jambor J. L.
Published: December 2006

Three of the members of the plagionite group, fülöppite Pb3S8S15, plagionite Pb5Sb8S17, and semseyite Pb9Sb8S21, show linear correlations of cell volume and density versus PbS:Sb2S3 mol ratios. This relationship can be used better to define the nature of the fourth member of the group, heteromorphite, Pb7Sb8S19. The cell dimensions derived for heteromorphite are a 13·60, b 11·93, c 21·22 Å, β 90° 50′.
Retrogression of eordierite to kyanite and andalusite at Fishtail Lake, Ontario, Canada
Authors: Lal R. K.
Published: December 2006

Cordierite commonly alters to chlorite-sericite, called pinite. Besides pinite alteration, cordierite from the Fishtail Lake shows textural evidence indicating retrogression to kyanite, andalusite, and coarse flakes of chlorite. This is consistent with the experimental data on the stability of cordierite and may be expected to be limited to potash-deficient rocks, such as the cordierite-garnetgedrite bearing gneisses of the area. In common potash-bearing pelitic rocks, retrogression of cordierite results in the formation of sericite and chlorite. In gneisses containing sillimanite and cordierite, the breakdown of cordierite in this way results in the association of the three aluminosilicates (kyanite, andalusite, and sillimanite) in the same rock. The association of kyanite-andalusite in equilibrium probably suggests that the retrogression of cordierite took place close to the univariant line of kyanite-andalusite.
Zeolites of the elinoptilolite–heulandite type in sediments of south-east England
Authors: Brown G. , Catt J. A. , Weir A. H.
Published: December 2006

Clinoptilolite-heulandite is reported from Jurassic, Cretaceous, and Palaeocene sediments in south-east England. It occurs mainly in 1–20 μm size fractions, and is associated with abundant montmorillonite and often also with glauconite and amorphous silica or low-temperature disordered cristobalite-tridymite. Its mode of occurrence and the associated minerals suggest an authigenic origin, but there is no evidence that the source material was volcanic.
The determination of the orthoclase content of homogenized alkali feldspars using the 2̄01 X-ray method
Authors: Jones J. B. , Nesbitt R. W. , Slade P. G.
Published: December 2006

Forty-three natural alkali feldspars have been homogenized and used to correlatewith wt % K2O. The regression of Or onis Or (wt %) = 465·5(Å)-1877·5, and is comparable to that obtained on an exchanged orthoclase (Wright, 1968). A deviation from the Orville (1963, 1967) determinative line for synthetic sanidine-albite is greatest at the high potassium end of the series. The discrepancy is not caused by failure to homogenize or incomplete disorder. The presence of cations other than potassium and sodium, or cation deficiency, or both cannot be discounted as a cause.
Phase relations in some tholeiitic lavas
illustrated by the system
R2O3–XO–YO–ZO2
Authors: Jamieson Brian G.
Published: December 2006

In order to aid the graphical presentation
of analyses of igneous rocks, a pseudo-quaternary
system
R2O3XO-YO-ZO2
has recently been used (O'Hara, 1968, fig. 4). To
test its ability to present the analytical data of
tholeiitic basalts, the analyses of selected lavas
have been projected into the system and then
sub-projected into two planes. Lines, which
represent the loci of liquid compositions in
certain isobaric, pseudo-univariant equilibria,
have been drawn on the basis of the melting
relations of the basalts. After reading the
pseudo-ternary phase diagrams resulting from the
sub-projections, some genetic aspects of the lavas
of Kilauea and Mauna Loa are discussed from a
phase equilibrium standpoint.
Further data on an ‘eclogite’ from the
Sittampundi Complex, India
Authors: Chappell B. W. , White A. J. R.
Published: December 2006

New analyses of a garnet-clinopyroxene
rock (‘eclogite’) and its constituent minerals
from the Sittampundi complex of India are
presented. The rock has a composition comparable
with an alkali-poor tholeiite and this
composition, as well as the garnet (Py 51·5 %; Alm
32·7 %) and pyroxene (Jd 7·4 %; Ts 10·8 %) are
very similar to those from South Harris.

The apparent distribution coefficient
(K′Fe/Mg) for the
garnet-clinopyroxene pair suggests a temperature
of equilibration near 850 °C. Projection of the
experimental data of Green and Ringwood (1967)
down to this temperature suggests a pressure of
about 7–8 kb. This is well below the pressure of
the granulite-eclogite transition.
Contributions to the synthesis of
spessartine analogues
Authors: Hříchová Renata
Published: December 2006

Many syntheses have been carried out in
order to establish the possibility of replacing
manganese in spessartine,
Mn3Al2(SiO4)3,
by various elements (Be, Mg, Ca, Sr, Ba, Pb, Cu,
Ni, Co, Fe2+, Sc, Yt, Zn, Cd)
as well as aluminium by Sc, Yt, Zr, Ti, Cr,
Fe3+ by a solid state
reaction. The syntheses were done by sintering
pellets of the desired composition at about 1100
°C for 5–10 hours under normal pressure. It has
been found that an inert atmosphere creates more
favourable conditions for the syntheses of
spessartine analogues, compared to the results
obtained in the open-air reaction, where often
spinel was obtained. All the reaction products
were submitted to X-ray and chemical analysis and
to IR spectroscopical examination.
The crystal structure of wardite
Authors: Fanfani L. , Nunzi A. , Zanazzi P. F.
Published: December 2006

Wardite,
NaAl3(OH)4(PO4)2.
2H2O, has
a = 7·03 Å,
c = 19·04 Å; space
group
P41212
or
P43212.
Its crystal structure was solved by a
three-dimensional Patterson function computed
using intensity data photographically collected by
the Weissenberg method, and refined by successive
Fourier maps and least-squares cycles to a
R index 0·062 for 316
independent observed reflections.

The wardite structure is formed by layers
of Al and Na coordination polyhedra sharing
vertices and edges. These sheets, parallel to the
a axes, are connected
to each other in the c
direction by PO4 tetrahedra
and H-bonds. This structural feature accounts for
the perfect {001} cleavage of wardite and explains
the change that occurs in lattice parameters when
Al is substituted by Fe in avelinoite. The
relationships with the minerals of the trigonal
families of crandallite, woodhouseite, and
jarosite are also discussed.
Lithiophorite from the Leeht mines,
Tomintoul, Banffshire
Authors: Wilson M. J. , Berrow M. L. , McHardy W. J.
Published: December 2006

The constituent manganese minerals of an
ore body located at the Lecht mines near Tomintoul
include cryptomelane and lithiophorite. The
latter, now known to occur extensively in soils,
was characterized by X-ray, thermal, and electron
microscope techniques. Lithiophorite yields a
distinctive differential thermal curve and this
was studied in some detail. A platy morphology is
revealed under the electron microscope and from
selected-area electron diffraction patterns it was
concluded that the b
parameter of the mineral is 8·73 Å, three times
the value determined by Wadsley (1952). As
suggested by Wadsley, this could arise from the
distribution of lithium ions. Chemical analysis
shows that the Lecht lithiophorite is slightly
unusual in that it has a high iron and zinc
content but is relatively low in cobalt. The
associated cryptomelane contains a significant
amount of thallium.
Bideauxite, a new Arizona mineral
Authors: Williams Sidney A.
Published: December 2006

Bideauxite is a new mineral found in specimens from the Mammoth-St. Anthony mine, Pinal County, Arizona. The composition is Pb2AgCl3(F,OH)2 with Pb, Ag, Cl, F by duplicate wet analyses. Z = 16, G. calc. 6·256, meas. 6·274 (at 24·2 °C). Crystals are isometric hexoctahedral with a 14·132 Å. Space group Fd3m. Crystals show a, o, d, m {113}, μ {114}, n {112}, φ {116}, and {029} in decreasing order of importance. Colourless, transparent with white streak. Isotropic with nD 2·192. le, almost sectile, withc onchoidal fracture. H = 3. Turns pale lavender in strong light. Low M.P. B.P. Decomposes in acids and warm NH4OH. Bideauxite is an oxide zone mineral found with leadhillite, matlockite, and anglesite. May alter to cerussite.
Hodrushite—a new sulphosalt
Authors: Koděra M. , Kupčík V. , Makovický E.
Published: December 2006

Hodrushite, a new sulphosalt of copper and bismuth, was found in the Rosalia ore vein at Banská Hodrušá near Banská Štiavnica, Czechoslovakia. It has chemical composition Cu8·12Bi11·54Fe0·29S22 (as determined by electron-microprobe method) close to Cu8Bi12S22. Symmetry is monoclinic, space group A2/m, lattice constants a 27·21, b 3·93, c 17·58 Å, β 92° 9′, measured density 6·35, calculated density 6·45 g/cm3. Microhardness 200 kg/mm2, anisotropic, weak bireflectance, creamy with pinkish tint, maximum reflectivity about 6000 Å. Crystals needle-shaped and striated along [010], colour steel-grey, quickly tarnishing to bronze. Associated with quartz, hematite, and chalcopyrite. Closely related to cuprobismutite.
A metallographic and microprobe study of the metal phases in the Weekeroo Station meteorite
Authors: Axon H. J. , Smith P. L.
Published: December 2006

The kamacite contains a general precipitation of micrometre-sized particles of exsolved taenite. Larger particles are found decorating Neumann lines and at kamacite grain boundaries. The coexisting kamacite and taenite appear to have nickel contents of 6·4 % and about 53%, which are consistent with a temperature of about 330–60 °C on the binary iron-nickel equilibrium diagram.
Topaz from the Meldon aplite, Devonshire
Authors: Nawaz Chaudhry M. , Howie R. A.
Published: December 2006

Chemical analyses, optical properties, specific gravities, and cell dimensions are presented for six topazes. A linear relationship is confirmed between the b cell dimension and the OH/(OH+F) ratio.
Medanitos and Putinga, two South American meteorites
Authors: Symes R. F. , Hutchison R.
Published: December 2006

Petrographic descriptions, bulk chemistry, and partial analyses of several mineral phases in each stone are presented. Medanitos, previously classed as a eucrite, is now shown to be a howardite: Putinga is an equilibrated olivine-hypersthene chondrite.
Nucleation and crystallization studies of some glasses in the CaO-MgO-Al2O3-SiO2 system
Authors: de Vekey R. C. , Majumdar A. J.
Published: December 2006

Glass-ceramics based on the mineral cordierite have good mechanical and thermal properties. They can be easily prepared from glasses whose compositions lie in the primary phase field of cordierite on the 5 % CaO plane of the CaO-MgO-SiO2-Al2O3 system. For uniform crystallization in the bulk, addition of a suitable nucleating agent is essential. The addition of 10–12 wt % of TiO2 is considered to be suitable for both ternary and quaternary glasses. During controlled heat treatment of these glasses extensive phase separation occurs. The nucleation and crystallization processes that follow have been studied by differential thermal analysis, X-ray diffraction, and light and electron microscopy. Some of the physical and mechanical properties of these glass-ceramics have been measured.
Crystallization of anorthite from CaO–Al2O3–SiO2 glasses
Authors: Bhatty M. S. Y. , Gard J. A. , Glasser F. P.
Published: December 2006

The X-ray powder diffraction pattern of synthetic anorthite crystallized from a CaO-Al2O3-SiO2 glass having the anorthite (1:1:2) molar ratio is identical with that reported in the literature, and also with that of a natural Japanese anorthite specimen. Increasing the CaO or SiO2 content of the parent glasses used for crystallization studies has no measurable effect on that portion of the powder pattern attributable to anorthite. However, glasses containing an excess of Al2O3 ranging from 5 to 10 mol % gave, after crystallization at temperatures below c. 1150 °C distinctively different powder pattern. Several powder reflections that are normally strong, such as , etc., were found to be virtually absent. Moreover, the chemical excess of Al2O3 did not appear as a separate alumina-bearing phase. Upon reheating these anorthites to temperatures above 1200–50 °C or upon crystallizing a fresh portion of alumina-rich glass above 1200-50 °C, only the normal anorthite powder X-ray pattern was obtained; the pattern also contained some reflections due to corundum (α-Al2O3). Examination of the anomalous low-temperature anorthite by electron diffraction shows that the apparent absence of some powder lines is caused by both albite and Carlsbad twinning, which occur on an intimate scale not exceeding a few unit cell repeats. From the unique manner of its occurrence, the twinning is believed to be associated with the inclusion of an excess of Al3+ in the anorthite.
The selection of grain-growth control additives for the sintering of ceramics
Authors: Budworth D. W.
Published: December 2006

The close interrelation between sintering and grain growth is discussed critically, and the necessity for control, but not suppression, of grain growth is established. A distinction between discontinuous and exaggerated grain growth is drawn, and the superiority of grain boundary films as grain-growth control agents is demonstrated. Work on the establishment of tentative criteria for the selection of grain-growth control additives for alumina is reviewed and discussed, and the extension of these ideas to the selection of NaF as a successful aid for magnesia is described.
Sintering and crystal growth of magnesia in the presence of lime and forsterite
Authors: Spencer D. R. F. , Coleman D. S.
Published: December 2006

The densification of pure magnesia was examined along with mixtures containing 0·5 and 1·0 mol % of calcium oxide and forsterite. The sintering behaviour at temperatures between 1400 and 1800 °C was studied and measurements made of changes in shrinkage, porosity, bulk density, and grain size for sintering times of up to 8 h at sintering temperature. It was found that both the 0·5 and 1·0 mol % additions enhanced the sintering of pure magnesia in the temperature range 1500–1700 °C Increased grain growth was found for mixtures containing forsterite but little change occurred for mixtures containing lime. Examination of the grain growth data showed that the mixtures obeyed a relationship: Time at temperature × Constant = (grain size)n, where n = 2 for the grain growth of pure magnesia and mixtures containing lime, but n = 3 for mixtures of magnesia with additions of a silicate such as forsterite. A value of 78 kcal/mole was obtained for the grain growth of pure magnesia, which agrees with other researches.

The extent of the solubility of lime in periclase for each lime-magnesia mixture at each temperature was also examined using electron probe analysis and related to the sintering behaviour observed for these mixtures.