On the relation of chamosite and daphnite to the chlorite group (With Plates XVIII and XIX.)

1939 ◽  
Vol 25 (167) ◽  
pp. 441-465 ◽  
Author(s):  
A. F. Hallimond
Keyword(s):  
Low Temperature ◽  
Simple Formula ◽  
British Museum ◽  
The Other ◽  
Geological Survey ◽  
Chemical Analyses ◽  
X Ray ◽  
Fine Grained ◽  
New Material ◽  
Crystalline Nature

There is a close optical and chemical resemblance between chamosite, the chloritic mineral of the bedded ironstones, and daphnite, a low-temperature vein-chlorite common in some of the Cornish tin mines. New material has made it possible to undertake a fresh comparison of the two minerals: chemical analyses have been made by Mr. C. O. Harvey, chemist to H.M. Geological Survey, and a report on the X-ray measurements is contributed by Mr. F. A. Bannister, of the Mineral Department of the British Museum.The new analysis of chamosite agrees with the simple formula previously assigned: X-ray examination of material from several localities has now established the distinctive crystalline nature of this fine-grained mineral, which differs structurally from ordinary chlorites such as clinochlore. Daphnite, on the other hand, has the ordinary chlorite structure, but the new analysis fully confirms Tschermak's original opinion that it cannot be represented chemically as a mixture of serpentine and amesite.

Russellite, a new British mineral

1938 ◽  
Vol 25 (161) ◽  
pp. 41-55 ◽  
Author(s):  
Max H. Hey ◽  
F. A. Bannister ◽  
Arthur Russell
Keyword(s):  
Chemical Analysis ◽  
British Museum ◽  
Bismuth Tungstate ◽  
X Ray ◽  
Pale Yellow ◽  
Fine Grained ◽  
Alteration Product ◽  
Spectroscopic Examination ◽  
Native Bismuth ◽  
And Tungsten

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

Triferrocenylborane – Molecular Structure in Solution and in the Solid State

1995 ◽  
Vol 50 (2) ◽  
pp. 201-204 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Udo Dörfler ◽  
Wolfgang Milius ◽  
Max Herberhold
Keyword(s):  
Molecular Structure ◽  
Solid State ◽  
Low Temperature ◽  
Single Crystal ◽  
Nmr Spectra ◽  
The Other ◽  
X Ray ◽  
Single Diastereomer ◽  
Structure In Solution ◽  
C Nmr

According to a single crystal X-ray structure determination all three ferrocenyl substituents of triferrocenylborane (1) adopt the same orientation with respect to the BC3-plane [P21/c monoclinic; Z = 4; a = 1353.5(3), b = 1695.6(3), c = 1056.4(2) pm, β = 109.27(3)°]. The simulated X-ray powder pattern of the single crystal is identical with the powder diagram of a macroscopic sample, indicating the presence of a single diastereomer (1a) in the solid state. However, at low temperature (< - 95 °C) in solution, the 13C NMR spectra suggest the presence of the second diastereomer (1b) in which one ferrocenyl group is oriented opposite to the other two with respect to the central BC3-plane.

Beiträge zur Chemie des Bors, 168 [1] Synthese und Struktur von Azadiboriridinen / Contributions to the Chemistry of Boron, 168 [1] Synthesis and Structure of Azadiboriridines

1986 ◽  
Vol 41 (1) ◽  
pp. 32-37 ◽  
Author(s):  
Franz Dirschl ◽  
Elisabeth Hanecker ◽  
Heinrich Nöth ◽  
Wilfried Rattay ◽  
Walter Wagner
Keyword(s):  
Low Temperature ◽  
Structure Analysis ◽  
Ring System ◽  
The Other ◽  
Ring Plane ◽  
X Ray ◽  
Restricted Rotation

Two representatives of the three membered B2N-ring system have been obtained by dehalogenation of diborylamines Me3CN[BHalNR2]2. In solution there is no restricted rotation at the exocyclic BN bond, even at low temperature. In contrast, the X-ray structure analysis of the bis-tetramethylpiperidino derivative 10a reveals alternation of short and long BN bonds; one of the tetramethylpiperidino groups stands nearly coplanar with the B2N-ring system, the other, however, is almost perpendicular to the ring plane. The ring contains a short BB bond (1.612 Å).

Influence of W additions in rapidly solidified nial

1987 ◽  
Vol 45 ◽  
pp. 212-213
Author(s):  
I. E. Locci ◽  
M. V. Nathal
Keyword(s):  
Low Temperature ◽  
Melt Spinning ◽  
Matrix Composition ◽  
X Ray ◽  
Fine Grained ◽  
Free Jet ◽  
High Temperature Structural Material ◽  
Low Temperature Toughness ◽  
Pure Metals ◽  
Rapidly Solidified

The B2 aluminide NiAl has potential as a high temperature structural material, although its lack of low temperature toughness is a major obstacle. One strategy for improving low temperature toughness is by grain refinement. Fortunately, fine grained intermetallics appear to retain their strengths to much higher fractions of their melting point than do pure metals and alloys. The purpose of this study was to investigate the effects of melt spinning and small W additions on the grain size and stability of NiAl.Two alloys of the same matrix composition, equiatomic NiAl, were examined. One also contained 0.5 W at% (NiAl+W). The alloys were cast as ribbon ∼45 pm thick by ∼2.5 mm wide using a free jet melt spinning apparatus. To simulate consolidation conditions, sections of ribbon were annealed for 1 hour at either 1273 or 1573 °K in purified argon. Optical, X-ray and electron analyses of the as-spun and annealed ribbons were performed.

Lithium–aluminium micas from the Meldon aplite, Devonshire, England

1973 ◽  
Vol 39 (303) ◽  
pp. 289-296 ◽  
Author(s):  
M. Nawaz Chaudhry ◽  
R. A. Howie
Keyword(s):  
Low Temperature ◽  
Refractive Indices ◽  
Compositional Variation ◽  
Chemical Analyses ◽  
X Ray ◽  
Octahedral Sites ◽  
Lithium Aluminium ◽  
Structural Types ◽  
Higher Temperature ◽  
The Relationship

SummaryChemical analyses of sixteen lithium-aluminium micas are presented along with their optical, physical, and X-ray data. Compositional variation, substitution relations in structural positions, and octahedral occupancy are discussed. The 2M2 structural types are found to crystallize in volatilerich low-temperature environments whereas the 1M polytypes occur in comparatively volatile-poor and higher-temperature environments. Variation diagrams have been constructed to show the relationship between octahedral sites occupied by and refractive indices and specific gravities.

Carbonate enrichment at the margins of a basic dyke, Ardnamurcha

1974 ◽  
Vol 39 (305) ◽  
pp. 514-524 ◽  
Author(s):  
M. K. Wells ◽  
A. C. S. Smith ◽  
J. F. W. Bowles
Keyword(s):  
Mineral Content ◽  
Microprobe Analysis ◽  
The Other ◽  
Transient Effects ◽  
Basic Dyke ◽  
X Ray ◽  
Fine Grained ◽  
Titaniferous Magnetite ◽  
Oxide Phases ◽  
Opaque Minerals

SummaryA gradational increase in concentration of CO2 towards the margins of a very fine-grained basalt dyke has led to the development of a pale marginal facies, enriched in carbonates, particularly siderite. Increases in CO2 from about 3 % in the interior of the dyke to 8 % at the margins are accompanied by decreases in SiO2 and Fe2O3, increases in Al2O3, and less significant changes in the other major components. Cu, Co, and Zn change only slightly, and Cr, Ni, and Li remain constant. Petrographic variation is considerable, even in the superficially homogeneous interior of the dyke, in which it ranges from a type containing a titanaugite (analysed) to one devoid of pyroxene, but containing conspicuous opaque minerals. Microprobe analysis for Fe and Ti shows that these comprise: cotahedral titaniferous magnetite; rodlets, less than 1 µm thick, of rutile partly altered to, or overgrown by, ilmenite; and sub-opaque patches with a very low Ti/Fe ratio. Plagioclase, An55, is the most abundant and constant crystalline phase in the interior of the dyke, but changes to An20 in the marginal facies. Mineral-content of the latter, deduced from optical, chemical, and X-ray data, also includes siderite, serpentine and clay minerals, leucoxene, and apatite. There is no evidence of quartz, sericite, or calcite.Petrographic evidence shows that variations in concentrations of CO2 and H2O affected phase equilibria from the start of magmatic crystallization. Data on the fO2 required for TiO2 and Fe-oxide phases to co-exist at magmatic temperatures indicate that, initially, the concentrations of CO2 and H2O in the interior of the dyke were higher than the values recorded in analyses of the rocks. From this evidence and the field relationships, it is concluded that the intruding magma was rich in volatiles, which diffused towards the dyke margins and, in part, became trapped as the magma congealed, producing a changed marginal assemblage of minerals. The dyke provides a unique glimpse of influences on a basic magma exerted by what S. J. Shand has aptly termed the ‘fugitive constituents’, the transient effects of which are rarely preserved in the rocks.

Nepheline solid solutions

1959 ◽  
Vol 32 (245) ◽  
pp. 93-109 ◽  
Author(s):  
Gabrielle Donnay ◽  
J. F. Schairer ◽  
J. D. H. Donnay
Keyword(s):  
Low Temperature ◽  
Cell Volume ◽  
Solid Solutions ◽  
Binary Systems ◽  
Calcium Content ◽  
Potassium Content ◽  
Chemical Analyses ◽  
X Ray ◽  
Cell Dimensions

SummaryPublished chemical analyses demonstrate that the nepheline formula should be written KxNayCaz□s-(x+y+z)Alx+y+2zSi16-(x+y+2z)O32, where □ stands for vacant sites. X-ray data are presented for the nepheline phase in four binary systems: Ne-CaAl2O4, Ne-An, Ne-Ab, Ne-Kp. Only in two of these systems do the cell-dimensions change with composition. In the first one, the cell-volume V increases linearly with increasing calcium content; in the last one, two singularities in the curve of V against x divide the phase Na8-xKxAl8Si8O32 into three subphases: subpotassic (0 < x < 0·25), mediopotassic (0·25 < x < 2·00), and perpotassic (2·00 < x < 4·73). Only in the subpotassic range are both high- and low-temperature forms found. Twenty-eight natural nephelines, for which chemical analyses and X-ray data are available in the literature, show that only the potassium content affects cell-dimensions. Although all analysed natural nephelines fall outside the subpotassic range, the re-examination of a Monte Somma specimen studied by Bannister (1931) reveals a few euhedral crystals of subpotassic nepheline in a mediopotassic phase.

The X-ray pattern of low-temperature cristobalite

1944 ◽  
Vol 27 (187) ◽  
pp. 54-55 ◽  
Author(s):  
A. H. Jay
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Open Hearth ◽  
Crystalline Material ◽  
The Other ◽  
Raw Material ◽  
X Ray ◽  
Temperature Heating ◽  
High Temperature Heating ◽  
Roof Brick

Cristobalite is found as the first product in the conversion of quartz following a high-temperature heating, and it constitutes a large percentage of the crystalline material in most manufactured silica bricks. It is present also in fireclay products, the amount being dependent upon the nature of the raw material and the conditions of firing. In the majority of these products the cristobalite is only poorly developed, i.e. the crystals are only perfect over distances of the order of about 1 × 10-6 cm. This value is derived from the diffuseness of the high-order reflections on the X-ray powder photograph. On the other hand, the crystals of cristobalite are well developed in the hot face of an open hearth silica roof-brick.

Low-temperature and high-pressure polymorphs of isopropyl alcohol

CrystEngComm ◽  
2014 ◽  
Vol 16 (32) ◽  
pp. 7397-7400 ◽  
Author(s):  
Joe Ridout ◽  
Michael R. Probert
Keyword(s):  
High Pressure ◽  
Low Temperature ◽  
Single Crystal ◽  
Isopropyl Alcohol ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray

Single-crystal X-ray diffraction has been used to elucidate the structure of two polymorphs of isopropyl alcohol, one grown through in situ cryo-crystallisation, the other through high-pressure crystallisation.

The nomenclature of the halloysite minerals

1947 ◽  
Vol 28 (196) ◽  
pp. 36-44 ◽  
Author(s):  
Douglas M. C. MacEwan
Keyword(s):  
Low Temperature ◽  
Bound Water ◽  
The Other ◽  
Hydrous Mineral ◽  
X Ray ◽  
Basal Reflection

The name ‘halloysite’, first used in 1826 by Berthier, is derived from that of Omalius d'Halloy, who found the mineral in Angleur, Liége, Belgium. In 1935, Mehmel discovered that there were two distinct substances included under the name halloysite, one of which contains loosely bound water and shows a 10 Å. basal reflection on an X-ray diagram, the other none and shows a reflection at about 7 Å. Mehmel preserved the name halloysite for the hydrous mineral, and for the product of its dehydration he proposed the name ‘metahalloysite’. Both substances may occur naturally (though this may not have been known to Mehmel at the time). Previous to this work it had been suggested by Hofmann, Endell, and Wilm that the 10 Å. material on dehydration at a low temperature gave kaolinite. Mehmel showed that this was wrong; and that the error was due to the similarity of the X-ray diagrams of kaolinite and metahalloysite. Hofmann and co-workers, and Mehmel, all tacitly assumed that the name halloysite was correctly applied to the 10 Å. material rather than the 7 Å. material.

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