scholarly journals Eudidymite and epididymite from the Ilímaussaq alkaline intrusion, South Greenland

1966 ◽  
Vol 63 ◽  
pp. 1-21
Author(s):  
E.I Semenov ◽  
H Sørensen
Keyword(s):  
Optical Properties ◽  
Kola Peninsula ◽  
Axial Plane ◽  
Alkali Granite ◽  
Chemical Analyses ◽  
X Ray ◽  
Fine Grained ◽  
Alkaline Intrusion ◽  
Mode Of Occurrence

Eudidymite has been discovered as lamellar or spherulitic aggregates in veins of albitite in alkali granite and in poikilitic nepheline-sodalite syenite (naujaite) in the Ilímaussaq alkaline intrusion, South Greenland. In the veins in granite it is associated with microcline, quartz, albite, arfvedsonite, ægirine, polylithionite, narsarsukite, monazite and elpidite. In naujaite eudidymite is associated with albite, microcline, fluorite, analcime, tugtupite, epididymite, genthelvite, neptunite, schizolite, lithium mica, ægirine, katapleiite, etc. Epididymite occurs as microcrystalline or fine-grained masses associated with analcime, albite, tugtupite, eudidymite leucophane, schizolite, etc. in veins of albitite in naujaite. The optical properties of the two minerals are: eudidymite: nα = 1.545, nγ = 1.549, 2 Vγ = 25°; epididymite: nα = 1.540, nγ = 1.544, 2 Vα = 16-26° with a pronounced crossed axial plane dispersion. Both minerals are polysynthetically twinned. Chemical analyses of the two minerals are recorded. The X-ray powder diagrams are identical with those of epididymite and eudidymite from Lovozero. Eudidymite and epididymite were formed during late albitization of naujaite. Their mode of occurrence recalls that of these two minerals at Lovozero, the Kola peninsula.

scholarly journals On beryllite and bertrandite from the Ilímaussaq alkaline intrusion, South Greenland

1967 ◽  
Vol 68 (5) ◽  
pp. 10-29
Author(s):  
S Andersen ◽  
I Sørensen
Keyword(s):  
Water Content ◽  
Late Stage ◽  
Water Pressure ◽  
Hydrothermal Fluids ◽  
Refractive Indices ◽  
Chemical Analyses ◽  
X Ray ◽  
Alkaline Intrusion ◽  
Mode Of Occurrence ◽  
Partial Water

The two beryllium silicates beryllite and bertrandite and their mode of occurrence are described from the Ilímaussaq alkaline intrusion. Optical and X-ray data are presented for the two minerals together with chemical analyses of two beryllite samples. The data for bertrandite correspond closely to those given for bertrandite from other localities. The identification of the beryllite is based on the similarity in X-ray data with the Lovozero type mineral. Pronounced differences from the latter are found in the refractive indices which are 1.50 < n < 1.52, and in the water content which varies in different samples from Ilímaussaq. The two minerals are associated with the beryllium minerals epididymite, eudidymite, chkalovite and sorensenite. The beryllium minerals are found in analcite veins and pockets formed in a late stage of the development of the complex. It is argued that differences in the partial water pressure of hydrothermal fluids govern the formation of the two minerals.

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.

scholarly journals A generalized photon-tracking approach to simulate spectral snow albedo and transmissivity using X-ray microtomography and geometric optics

2021 ◽  
Author(s):  
Theodore Letcher ◽  
Julie Parno ◽  
Zoe Courville ◽  
Lauren Farnsworth ◽  
Jason Olivier
Keyword(s):  
Optical Properties ◽  
Coarse Grained ◽  
East Central ◽  
X Ray ◽  
Fine Grained ◽  
Potential Applications ◽  
Visible Wavelengths ◽  
Tracing Techniques ◽  
Bidirectional Reflectance Distribution ◽  
Snow Samples

Abstract. A majority of snow radiative transfer models (RTM) treat snow as a collection of idealized grains rather than a semi-organized ice-air matrix. Here we present a generalized multi-layer photon-tracking RTM that simulates light transmissivity and reflectivity through snow based on x-ray microtomography, treating snow as a coherent structure rather than a collection of grains. Notably, the model uses a blended approach to expand ray-tracing techniques applied to sub-1 cm3 snow samples to snowpacks of arbitrary depths. While this framework has many potential applications, this study's effort is focused on simulating light transmissivity through thin snowpacks as this is relevant for surface energy balance applications and sub-nivean hazard detection. We demonstrate that this framework capably reproduces many known optical properties of a snow surface, including the dependence of spectral reflectance on snow grain size and incident zenith angle and the surface bidirectional reflectance distribution function (BRDF). To evaluate how the model simulates transmissivity, we compare it against spectroradiometer measurements collected at a field site in east-central Vermont. In this experiment, painted panels were inserted at various depths beneath the snow to emulate thin snow. The model compares remarkably well against the spectroradiometer measurements. Sensitivity simulations using this model indicate that snow transmissivity is greatest in the visible wavelengths and is limited to the top 5 cm of the snowpack for fine-grained snow, but can penetrate as deep as 8 cm for coarser grain snow. An evaluation of snow optical properties generated from a variety of snow samples suggests that coarse grained low density snow is most transmissive.

Davidlloydite, ideally Zn3(AsO4)2(H2O)4, a new arsenate mineral from the Tsumeb mine, Otjikoto (Oshikoto) region, Namibia: description and crystal structure

2012 ◽  
Vol 76 (1) ◽  
pp. 45-57 ◽  
Author(s):  
F.C. Hawthorne ◽  
M. A. Cooper ◽  
Y. A. Abdu ◽  
N. A. Ball ◽  
M. E. Back ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Optical Properties ◽  
Direct Methods ◽  
Crystal Structure Analysis ◽  
Width Ratio ◽  
Calculated Density ◽  
Triclinic Space Group ◽  
X Ray ◽  
Fine Grained ◽  
Mohs Hardness

AbstractDavidlloydite, ideally Zn3(AsO4)2(H2O)4, is a new supergene mineral from the Tsumeb mine, Otjikoto (Oshikoto) region, Namibia. It occurs as elongated prisms (∼10:1 length-to-width ratio) that are flattened on {010}, and up to 100 × 20 × 10 μm in size. The crystals occur as aggregates (up to 500 μm across) of subparallel to slightly diverging prisms lying partly on and partly embedded in fine-grained calcioandyrobertsite. Crystals are prismatic along [001] and flattened on {010}, and show the forms {010} dominant and {100} subsidiary. Davidlloydite is colourless with a white streak and a vitreous lustre; it does not fluoresce under ultraviolet light. The cleavage is distinct on {010}, and no parting or twinning was observed. The Mohs hardness is 3 – 4. Davidlloydite is brittle with an irregular to hackly fracture. The calculated density is 3.661 g cm–3. Optical properties were measured with a Bloss spindle stage for the wavelength 590 nm using a gel filter. The indices of refraction are α = 1.671, β = 1.687, γ = 1.695, all ±0.002; the calculated birefringence is 0.024; 2Vobs = 65.4(6)°, 2Vcalc = 70°; the dispersion is r < v, weak; pleochroism was not observed. Davidlloydite is triclinic, space group P1, with a = 5.9756(4), b = 7.6002(5), c = 5.4471(4) Å, α = 84.2892(9), β = 90.4920(9), γ = 87.9958(9)°, V = 245.99(5) Å3, Z = 1 and a:b:c = 0.7861:1:0.7167. The seven strongest lines in the X-ray powder diffraction pattern [listed as d (Å), I, (hkl)] are as follows: 4.620, 100, (011, 10); 7.526, 71, (010); 2.974, 49, (200, 01); 3.253, 40, (021, 120); 2.701, 39, (10, 002, 1); 5.409, 37, (001); 2.810, 37, (210). Chemical analysis by electron microprobe gave As2O5 43.03, ZnO 37.95, CuO 5.65, H2O(calc) 13.27, sum 99.90 wt.%. The H2O content and the valence state of As were determined by crystal structure analysis. On the basis of 12 anions with H2O = 4 a.p.f.u., the empirical formula is (Zn2.53Cu0.39)Σ2.92As2.03O8(H2O)4.The crystal structure of davidlloydite was solved by direct methods and refined to an R1 index of 1.51% based on 1422 unique observed reflections collected on a three-circle rotating-anode (MoKα radiation) diffractometer equipped with multilayer optics and an APEX-II detector. In the structure of davidlloydite, sheets of corner-sharing (As5+O4) and (ZnO4) tetrahedra are linked by ZnO2(H2O)4 octahedra. The structure is related to that of parahopeite.

scholarly journals Impact of beryllium microstructure on the imaging and optical properties of X-ray refractive lenses

2020 ◽  
Vol 27 (1) ◽  
pp. 44-50
Author(s):  
Ivan Lyatun ◽  
Peter Ershov ◽  
Irina Snigireva ◽  
Anatoly Snigirev
Keyword(s):  
Optical Properties ◽  
Direct Consequence ◽  
Fourth Generation ◽  
X Rays ◽  
Transmission Microscopy ◽  
X Ray ◽  
Fine Grained ◽  
Speckle Patterns ◽  
Materials Used ◽  
Almost All

Beryllium is one of the most transparent materials to hard X-ray radiation and, as a direct consequence, it is the main material for the fabrication of X-ray refractive optics and instrumentation for synchrotron radiation sources and free-electron laser facilities. However, it is known that almost all beryllium currently in use is polycrystalline material. In this paper, the influence of the microstructure of different beryllium grades on the optical properties of X-ray refractive lenses is studied. The experiments were performed at the ESRF ID06 beamline in X-ray coherent transmission microscopy mode in the near- and far-fields. Two sets of refractive lenses made of beryllium O-30-H and IS-50M grades with different internal microstructure were used. It was found that both beryllium grades have a strongly inhomogeneous structure, which inevitably produces speckle patterns under coherent illumination in imaging experiments. It was shown that fine-grained beryllium O-30-H is better suited for imaging applications, whereas beryllium IS-50M with a relatively large grain microstructure is more appropriate for focusing and collimation of X-rays. A discussion on the requirements for X-ray optical materials used at the third- and fourth-generation synchrotrons is also presented.

Priderite, a new mineral from the leucite-lamproites of the west Kimberley area, Western Australia

1951 ◽  
Vol 29 (212) ◽  
pp. 496-501 ◽  
Author(s):  
K. Norrish
Keyword(s):  
Optical Properties ◽  
Western Australia ◽  
New Mineral ◽  
X Ray Diffraction ◽  
The West ◽  
X Ray ◽  
Fine Grained

During an analysis by X-ray diffraction techniques of some fine-grained leucite-lamproites from the west Kimberley area of Western Australia the author became interested in the rntile in these rocks. Although rutile had been repeatedly observed under the microscope (1, 2), its presence could not be confirmed using X-ray diffraction methods. At the author's request, Professor R. T. Prider supplied a small amount of the mineral which had been identified as rutile. A study of this mineral showed it to be a new mineral similar to rutile in its optical properties.

Structural and optical properties of Tin Oxide and Indium doped SnO2 thin films deposited by thermal evaporation technique

2016 ◽  
Vol 12 (3) ◽  
pp. 4394-4399
Author(s):  
Sura Ali Noaman ◽  
Rashid Owaid Kadhim ◽  
Saleem Azara Hussain
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Tin Oxide ◽  
Thermal Evaporation ◽  
Pure Sno2 ◽  
X Ray Diffraction ◽  
Structural And Optical Properties ◽  
X Ray ◽  
Evaporation Technique ◽  
Sno2 Thin Films

Tin Oxide and Indium doped Tin Oxide (SnO2:In) thin films were deposited on glass and Silicon  substrates  by  thermal evaporation technique.  X-ray diffraction pattern of  pure SnO2 and SnO2:In thin films annealed at 650oC and the results showed  that the structure have tetragonal phase with preferred orientation in (110) plane. AFM studies showed an inhibition of grain growth with increase in indium concentration. SEM studies of pure  SnO2 and  Indium doped tin oxide (SnO2:In) ) thin films showed that the films with regular distribution of particles and they have spherical shape.  Optical properties such as  Transmission , optical band-gap have been measured and calculated.

The Coordination Chemistry of Phosphoryl Compounds Containing the — N(CH3)2 Group, Part VIII

1972 ◽  
Vol 27 (7) ◽  
pp. 759-763 ◽  
Author(s):  
M. W. G. De Bolster ◽  
W. L. Groeneveld
Keyword(s):  
Coordination Chemistry ◽  
General Formula ◽  
Ligand Field ◽  
Chemical Analyses ◽  
X Ray ◽  
Physical Measurements ◽  
Ligand Field Spectra ◽  
Chloride Adduct ◽  
Ligand Field Parameters ◽  
Group Part

A number of new solvates and adducts containing bisphenyldimethylaminophosphine oxide is reported. The solvates have the general formula M[(C6H5)2P(O)N(CH3)2]42+(anion-)2, in which M = Mg, Ca, Mn, Fe, Co, Ni, Cu, Zn and Cd, and the anions are ClO4- and BF4-. The adducts have the general formula M[(C6H5)2P(O)N(CH3)2]2Cl2, where M stands for the same series of metals.The compounds are characterized and identified by chemical analyses and physical measurements.Ligand-field and vibrational spectra have been investigated; values for the ligand-field parameters are reported. It is concluded that coordination takes place via the oxygen atom of the ligand.X-ray powder patterns were used in combination with ligand-field spectra to deduce the coordination around the metal ions.The interesting behaviour of the nickel (II) chloride adduct upon heating is discussed and it is shown that both a square pyramidal and a tetrahedral modification exists.

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