Cell parameters refinements showing an influence of the chemical nature of the grain surface on the crystalline characteristics of fine grained powders

1998 ◽  
Vol 08 (PR5) ◽  
pp. Pr5-85-Pr5-89
Author(s):  
P. Sarrazin ◽  
F. Bernard ◽  
G. Calvarin ◽  
J. C. Niepce ◽  
B. Thierry
Keyword(s):  
Chemical Nature ◽  
Cell Parameters ◽  
Fine Grained ◽  
Grain Surface

Heklaite, KNaSiF6, a new fumarolic mineral from Hekla volcano, Iceland

2010 ◽  
Vol 74 (1) ◽  
pp. 147-157 ◽  
Author(s):  
A. Garavelli ◽  
T. Balić-Žunić ◽  
D. Mitolo ◽  
P. Acquafredda ◽  
E. Leonardsen ◽  
...  
Keyword(s):  
Powder Diffraction ◽  
Quantitative Chemical Analysis ◽  
Unit Cell Parameters ◽  
Orthorhombic Space Group ◽  
Synthetic Compound ◽  
Calculated Density ◽  
X Ray ◽  
Cell Parameters ◽  
Fine Grained ◽  
The Ideal

AbstractHeklaite, with the ideal formula KNaSiF6, was found among fumarolic encrustations collected in 1992 on the Hekla volcano, Iceland. Heklaite forms a fine-grained mass of micron- to sub-micron-sized crystals intimately associated with malladrite, hieratite and ralstonite. The mineral is colourless, transparent, non-fluorescent, has a vitreous lustre and a white streak. The calculated density is 2.69 g cm–3. An SEM-EDS quantitative chemical analysis shows the following range of concentrations (wt.%): Na 11.61–12.74 (average 11.98), K 17.02–18.97 (average 18.29), Si 13.48 –14.17 (average 13.91), F 54.88–56.19 (average 55.66). The empirical chemical formula, calculated on the basis of 9 a.p.f.u., is Na1.07K0.96Si1.01F5.97. X-ray powder diffraction indicates that heklaite is orthorhombic, space group Pnma, with the following unit-cell parameters: a = 9.3387(7) Å, b = 5.5032(4) Å, c = 9.7957(8) Å , V = 503.43(7) Å3, Z = 4. The eight strongest reflections in the powder diffraction pattern [d in Å (I/I0) (hkl)] are: 4.33 (53) (102); 4.26 (56) (111); 3.40 (49) (112); 3.37 (47) (202); 3.34 (100) (211); 2.251 (27) (303); 2.050 (52) (123); 2.016 (29) (321). On the basis of chemical analyses and X-ray data, heklaite corresponds to the synthetic compound KNaSiF6. The name is for the type locality, the Hekla volcano, Iceland.

scholarly journals Margarite pseudomorphs after corundum, Qôrqut area, Godthåbsfjord, West Greenland

1983 ◽  
Vol 112 ◽  
pp. 95-99
Author(s):  
R.F Dymek
Keyword(s):  
Chemical Data ◽  
Maximum Temperature ◽  
West Greenland ◽  
Cell Parameters ◽  
Fine Grained ◽  
Retrograde Reaction ◽  
Fine Grained Material ◽  
Dispersed Material

Margarite (end member CaAI2Si2AI2O1O) is reported as nodular aggregates of fine-grained material partly replacing corundum and as fine dispersed material replacing biotite in an inclusion of migmatitic plagioclase-rich gneiss within the Qôrqut granite. Muscovite replaces biotite in the same sample. A retrograde reaction in the presence of volatiles is suggested in which biotite + plagioclase + corundum go to an assemblage containing margarite + muscovite + epidote. Cell parameters and chemical data are presented. A maximum temperature for the reaction of - 5800 at 5 Kb is suggested.

scholarly journals An innovative approach for provenancing ancient white marbles: the contribution of x-ray diffraction to disentangling the origins of Göktepe and Carrara marbles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
F. Antonelli ◽  
F. Nestola
Keyword(s):  
Low Cost ◽  
X Ray Diffraction ◽  
Routine Procedure ◽  
Unit Cell Parameters ◽  
Strontium Content ◽  
X Ray ◽  
Cell Parameters ◽  
Fine Grained ◽  
Laboratory Techniques ◽  
Crystallographic Feature

AbstractThe paper presents a very efficient, quick, low-cost and minimally micro-destructive approach to discriminating between Roman artefacts sculpted with Göktepe (Aphrodisia, Turkey) or Carrara (Apuan Alps, Italy) white marbles by using a standard X-Ray Powder Diffractometer (XRPD) and a refinement of the unit cell parameters and volume of calcite. At present, the routine way of differentiating between these two almost indistinguishable by-eye marbles is based on the typically higher strontium content of calcite in the Microasiatic lithotype, a unique geochemical-crystallographic feature with respect to all other non-Göktepe fine-grained white marbles used in classical times. The XRPD approach has been verified by testing eighteen samples of known composition, nine from Carrara and nine from Göktepe quarries, which had already been analysed with other laboratory techniques. The applicability of the method to archaeological artefacts was confirmed by an archaeometric study performed on some famous Roman sculptures of the National Archaeological Museum of Venice and from Hadrian’s Villa at Tivoli. The results show that Göktepe/Carrara discrimination is always possible and that this XRPD approach can potentially become a useful and low-cost routine procedure to solve provenance issues.

Nordgauite, MnAl2(PO4)2(F,OH)2·5H2O, a new mineral from the Hagendorf-Süd pegmatite, Bavaria, Germany: description and crystal structure

2011 ◽  
Vol 75 (2) ◽  
pp. 269-278 ◽  
Author(s):  
W. D. Birch ◽  
I. E. Grey ◽  
S. J. Mills ◽  
A. Pring ◽  
C. Bougerol ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Optical Properties ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
New Mineral ◽  
Unit Cell Parameters ◽  
Triclinic Space Group ◽  
Cell Parameters ◽  
Fine Grained ◽  
Synchrotron Xrd

AbstractNordgauite, MnAl2(PO4)2(F,OH)2·5H2O, is a new secondary phosphate from the Hagendorf-Süd pegmatite, Bavaria, Germany. It occurs as white to off-white compact waxy nodules and soft fibrous aggregates a few millimetres across in altered zwieselite—triplite. Individual crystals are tabular prismatic, up to 200 μ long and 10 μ wide. Associated minerals include fluorapatite, sphalerite, uraninite, a columbite—tantalite phase, metastrengite, several unnamed members of the whiteite—jahnsite family, and a new analogue of kingsmountite. The fine-grained nature of nordgauite meant that only limited physical and optical properties could be obtained; streak is white; fracture, cleavage and twinning cannot be discerned. Dmeas. and Dcaic. are 2.35 and 2.46 g cm–3, respectively; the average RI is n = 1.57; the Gladstone-Dale compatibility is —0.050 (good). Electron microprobe analysis gives (wt.%): CaO 0.96. MgO 0.12, MnO 14.29, FeO 0.60, ZnO 0.24, A12O3 22.84, P2O5 31.62, F 5.13 and H2O 22.86 (by CHNX less F=O 2.16, total 96.50. The corresponding empirical formula is (Mn0.90Ca0.08Fe0.04Zn0.01Mg0.01)-Σi.04Ai2.0i(PO4)2[F1.21,(OH)0.90]Σ2.11·5.25H2O. Nordgauite is triclinic, space group P1̄, with the unit-cell parameters: a = 9.920(4), b = 9.933(3), c = 6.087(2) Å, α = 92.19(3), β = 100.04(3), γ = 97.61(3)°, V = 584.2(9) Å3 and Z = 2. The strongest lines in the XRD powder pattern are [d in Å (I) (hkl)] 9.806 (100)(010), 7.432 (40)(l1̄0), 4.119 (20)(210), 2.951 (16)(031), 4.596 (12)(21̄O), 3.225 (12)(220) and 3.215 (12)(121). The structure of nordgauite was solved using synchrotron XRD data collected on a 60 μm × 3 μm × 4 μm needle and refined to R1 = 0.0427 for 2374 observed reflections with F > 4σ(F). Although nordgauite shows stoichiometric similarities to mangangordonite and kastningite, its structure is more closely related to those of vauxite and montgomeryite in containing zig-zag strings of corner-connected Al-centred octahedra along [011], where the shared corners are alternately in cis and trans configuration. These chains link through corner-sharing with PO4 tetrahedra along [001] to form (100) slabs that are interconnected via edge-shared dimers of MnO6 polyhedra and other PO4 tetrahedra.

scholarly journals Mineralogie křemenných žil ložiska cínových rud Hřebečná u Abertam v Krušných horách (Česká republika)

2021 ◽  
Vol 29 (1) ◽  
pp. 131-163
Author(s):  
Jiří Sejkora ◽  
Petr Pauliš ◽  
Michal Urban ◽  
Zdeněk Dolníček ◽  
Jana Ulmanová ◽  
...  
Keyword(s):  
Coarse Grained ◽  
Powder Diffraction Data ◽  
Vein Quartz ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Fine Grained ◽  
Mineral Phases ◽  
Supergene Processes ◽  
Krušné Hory Mountains

An extraordinary rich mineral assemblage (more than 35 determined mineral species) has been discovered in quartz greisen mineralization found at dump material of the abandoned Mauritius mine. This mine is situated about 1 km N of the Hřebečná village, 16 km N of Karlovy Vary, Krušné hory Mountains, Czech Republic. The studied mineralization with its textural and mineralogical character differs significantly from the usual fine-grained greisens mined in this area. The primary mineralization is represented by coarse-grained quartz and fluorapatite with sporadic zircon, monazite-(Ce), xenotime-(Y) and very rare cassiterite. Besides common sulphides (arsenopyrite, chalcopyrite, pyrite, sphalerite, tetrahedrite-group minerals), Bi-sulphosalts (aikinite, bismuthinite, berryite, cuprobismutite, emplectite, wittichenite) were determined. Members of the tetrahedrite group also contain increased amounts of Bi - in addition to Bi-rich tennantite-(Zn) and tennantite-(Fe), microscopic zones represented by the not approved Bi-dominant analogue of tennantite („annivite-(Zn)“) were also found. The primary mineralization was intensively affected by supergene processes. Chalcopyrite and sphalerite are replaced by Cu sulphides - especially anilite and digenite, and more rarely by geerite, spionkopite and covellite. Some of the fluorapatite grains in the vein quartz were decomposed and mrázekite, mixite, libethenite, pseudomalachite, hydroxylpyromorphite, metatorbernite as well as rare dzhalindite crystallized in the resulting cavities. However, the most abundant supergene phases are the minerals of the alunite supergroup - crandallite, goyazite, plumbogummite, svanbergite and waylandite. The detailed descriptions, X-ray powder diffraction data, refined unit-cell parameters and quantitative chemical composition of individual studied mineral phases are presented.

Peisleyite, a new sodium aluminium sulphate phosphate

1982 ◽  
Vol 46 (341) ◽  
pp. 449-452 ◽  
Author(s):  
E. S. Pilkington ◽  
E. R. Segnit ◽  
J. A. Watts
Keyword(s):  
South Australia ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Aluminium Sulphate ◽  
X Ray ◽  
Cell Parameters ◽  
Fine Grained ◽  
White Material ◽  
The Ideal

AbstractA new sodium aluminium sulphate phosphate has been named peisleyite. It has the ideal formula Na3Al16(SO4)2(PO4)10(OH)17 · 20H2O. It occurs as fine-grained, compact, brittle, white material on dumps at Tom's Phosphate Quarry, near Kapunda, South Australia. Strongest X-ray diffraction lines are 12.63 Å (100) 010, 7.82(35) 11, 5.41(35) 004, 7.59(30) 111. Unit cell parameters are a 13.31 ± 0.006, b 12.62 ± 0.006, c 23.15 ± 0.01 Å, β 110.0°±0.03°, Z = 2.

scholarly journals The radioactivity and the chemical nature of additives as factors determining the photocatalytic activity of TiO2

2012 ◽  
Vol 10 (6) ◽  
pp. 1850-1858
Author(s):  
Maria Milanova ◽  
Petya Kovacheva ◽  
Radina Kralchevska ◽  
Jovo Kolev ◽  
Joana Zaharieva ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Chemical Nature ◽  
Sol Gel ◽  
Solar Irradiation ◽  
X Ray Diffraction ◽  
Cell Parameters ◽  
Degradation Rate Constant ◽  
Reported Data ◽  
Sol Gel Synthesis ◽  
Tio2 Phase

AbstractMicrocomposites consisting of TiO2 and ThF4 or UO3 (0.5–2% of the TiO2 mass) are produced by sol-gel synthesis of TiO2 in presence of the respective additives. X-ray diffraction study reveals small effect of the latter on TiO2 phase composition and cell parameters and significant influence on the crystallite size and UV/Vis reflectance spectra. The photocatalytic tests in presence of TiO2-ThF4 microcomposites under UV and solar irradiation show a non-monotonic increase of the Malachite Green degradation rate constant with the increase of ThF4-content. No changes in the photocatalytic activity are observed in the presence of UO3 but the latter composites exhibit activity in darkness. The results are compared with previously reported data on the performance of TiO2-ThO2 photocatalyst with the same radioactivity and suggest that both radioactivity and the chemical nature of the dopants are responsible for the photocatalytic performance of TiO2-based composites containing radioactive substances.

Měděná mineralizace z Horní Halže u Měděnce v Krušných horách (Česká republika)

2021 ◽  
Vol 29 (2) ◽  
pp. 351-368
Author(s):  
Jiří Sejkora ◽  
Petr Pauliš ◽  
Roman Gramblička ◽  
Zdeněk Dolníček ◽  
Jana Ulmanová ◽  
...  
Keyword(s):  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Fine Grained ◽  
Copper Mineralization ◽  
Mineral Phases ◽  
Hydrothermal Stage ◽  
Supergene Processes ◽  
Mine Dump ◽  
The Ideal

An interesting copper mineralization has been discovered in fragments of hydrothermal quartz gangue found in dump material of the abandoned unnamed gallery 1.5 km S from Horní Halže (now part of the Měděnec village), the Krušné hory Mts., Czech Republic. The primary mineralization represented by fine-grained quartz, hematite, pyrite and probably also djurleite was intensively affected by supergene processes. Djurleite and pyrite are partly replaced by Cu sulphides - roxbyite, anilite, spionkopite and covellite. The origin of association bornite/half-bornite/anilite found in some samples can be analogous, although in this case it cannot be ruled out that it may be the result of decomposition of the original solid solution (against the ideal bornite clearly enriched in Cu) formed in the hydrothermal stage. The formation of other Cu minerals (malachite, brochantite, libethenite and pseudomalachite) and goethite is already clearly bound to supergene conditions, part of malachite and brochantite was then formed by (sub)recent weathering of Cu-sulphides in the mine dump material. The detailed descriptions, X-ray powder diffraction data, refined unit-cell parameters and quantitative chemical composition of individual studied mineral phases are presented.

Grguricite, CaCr2(CO3)2(OH)4.4H2O, a new alumohydrocalcite analogue

2020 ◽  
Vol 84 (5) ◽  
pp. 778-784
Author(s):  
Michael S. Rumsey ◽  
Mark D. Welch ◽  
John Spratt ◽  
Annette K. Kleppe
Keyword(s):  
Diffraction Data ◽  
Formula Unit ◽  
X Ray Diffraction ◽  
Cation Composition ◽  
Close Match ◽  
X Ray ◽  
Cell Parameters ◽  
Fine Grained ◽  
Crystalline Aggregates ◽  
Water Contents

AbstractThe occurrence and characterisation of a new member of the dundasite group are reported. Grguricite, ideally CaCr2(CO3)2(OH)4⋅4H2O, is the Cr analogue of alumohydrocalcite, CaAl2(CO3)2(OH)4⋅4H2O and occurs as lilac crusts of very fine-grained crystalline aggregates in the Pb–Ba–V mineralisation found at the Adeghoual Mine, Mibladen, Morocco (32°46′0″N, 4°37′59″W). The identification was based upon a close match with the powder X-ray diffraction data for alumohydrocalcite, the confirmation of anion components identified by Raman spectroscopy and the cation composition determined by electron-probe microanalysis. The empirical formula based upon 14 oxygen atoms per formula unit is Ca0.84Pb0.03Cr1.65Al0.39Mg0.02(CO3)2(OH)4⋅4H2O, with carbonate, hydroxyl and water contents set to those of the alumohydrocalcite stoichiometry. The fine-grained nature of the crystals (c. 0.5 μm × 0.1 μm × 5 μm) precluded a single-crystal X-ray study and both density and optical determinations. Grguricite is triclinic with space group P${\bar 1}$. Unit-cell parameters refined from the powder diffraction data are: a = 5.724(2), b = 6.5304(9), c = 14.646(4) Å, α = 81.682(1), β = 83.712(2), γ = 86.365(2)°, V = 537.8(2) Å3 and Z = 2. The five strongest peaks in the powder pattern are [dhkl, Å (I/Imax)(hkl)]: 6.222(100)(011), 3.227(87)(020), 6.454(63)(010), 2.883(58)(005, 023, 121) and 7.208(45)(002). The mineral is named after Australian geologist Ben Grguric.

Distinguishing among schoepite, [(UO2)8O2(OH)12](H2O)12, and related minerals by X-ray powder diffraction

1997 ◽  
Vol 12 (4) ◽  
pp. 230-238 ◽  
Author(s):  
Robert J. Finch ◽  
Frank C. Hawthorne ◽  
Mark L. Miller ◽  
Rodney C. Ewing
Keyword(s):  
Powder Diffraction ◽  
Unit Cell ◽  
Powder Diffraction File ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Fine Grained ◽  
Fine Grained Material ◽  
Two Phases ◽  
Atomic Parameters

We have calculated X-ray powder-diffraction data for schoepite, [(UO2)8O2(OH)12](H2O)12, using unit-cell and atomic parameters from the crystal structure (a14.337,b16.813,c14.781,Z=4,Dx=4.87gcm−3). Schoepite crystallizes in space groupP21cabut is strongly pseudo- centrosymmetric, and observed reflections (Irel>0.1%) conform to space groupPbca. The six strongest reflections for schoepite are [d(Å),hkl(relative intensity)] 7.365,002(100), 3.253,242(55), 3.626,240(36), 3.223,402(25), 3.683,004(20), 2.584,244(18). The calculated intensities of reflections that distinguish space groupPbcafrom space groupPbna(the space group of metaschoepite), i.e.,h0lwithhodd andleven, are weak, and may not be evident in experimental powder patterns. Theaaxis of schoepite (14.34 Å) is significantly longer than that of synthetic metaschoepite (13.98 Å), and the two phases can best be distinguished by their unit-cell parameters. However, potential overlap of the strongest reflections can make identification and unit-cell determination difficult, especially for fine-grained material. Natural samples commonly contain intergrowths of schoepite, metaschoepite, and dehydrated schoepite. The calculated powder pattern for schoepite agrees well with data reported for natural schoepite (PDF 13-241) but shows discrepancies with the data from synthesis products. Data for “synthetic schoepite” indicate that this product was a mixture. Powder data labeled “paraschoepite” in the Powder Diffraction File do not correspond to the mineral of that name.

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