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  • 1
    Electronic Resource
    Electronic Resource
    The crystal structure of hiortdahlite I (1985)
    Springer
    Mineralogy and petrology 34 (1985), S. 297-310 
    Details
    ISSN: 1438-1168
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Zusammenfassung Die Kristallstruktur des Hjortdahlits I (triklin, $$P\bar 1$$ ,a=11,0149(9),b=10,9409 (9),c=7,3534(3) Å, α=109,350(3), β=109,879(4), γ=83,434(4)o wurde unter Verwendung von 2910 Reflexen bestimmt und aufR 1=0.058 bzw.R 2=0,055 verfeinert. Das Ergebnis der Strukturbestimmung bestätigte, daß Hjortdahlit jene Züge zeigt, die der ganzen Mineralreihe in der Cuspidin-Gruppe gemeinsam sind, nämlich “Oktaeder-Wände”, die vier Kolonnen breit sind, parallel zuc verlaufen und über gemeinsame Ecken sowie über Si2O7-Gruppen miteinander verknüpft sind. Die Kationenverteilung in den Oktaeder-Wänden und die Lokalisation der Fluor-Anionen wurden bestimmt und diskutiert. Die kristallchemische Formel, welche aus dem Studium der Struktur erhalten wurde, lautet (Na3,2Ca0,8)Ca8Zr2M2(Si2O7)4O2,8F5,2, worin M eine gemischt besetzte Punktlage mit der durchschnittlichen Ladung drei bedeutet.
    Notes: Summary The crystal structure of hiortdahlite I (triclinic, $$P\bar 1$$ ,a=11.0149(9),b=10.9409(9),c=7.3534(3), α=109.350(3), β=109.879(4), γ=83.434(4)) was determined and refined using 2910 reflections toR 1=0.058 andR 2=0.055. The results of the structure determination confirmed that hiortdahlite presents the features common to the whole series of minerals in the cuspidine group, namely “octahedral walls”, four columns large and running parallel toc, interconnected by corner sharing and through Si2O7 groups. The cation distribution in the polyhedral walls and the location of the fluorine anions were determined and discussed. The crystal-chemical formula obtained from the structural study is (Na3.2Ca0.8)Ca8Zr2M2(Si2O7)4O2.8F5.2 where M represents a mixing site with average charge three.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01082969
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  • 2
    Electronic Resource
    Electronic Resource
    The crystal structure of Hiortdahlite II (1987)
    Springer
    Mineralogy and petrology 37 (1987), S. 25-35 
    Details
    ISSN: 1438-1168
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Zusammenfassung Die Kristallstruktur des Hjortdahlits II [triklin P1,a = 11,012(6),b = 10,342(3),c = 7,359(3)Å, a = 89,92(2), β = 109,21 (5),y= 90,06(3)°] wurde mit 1793 Reflexen bestimmt und aufR 1 = 0,069 bzw.R 2 = 0,066 verfeinert. Das Ergebnis der Strukturuntersuchung zeigt, daß der Hjortdahlit II jene Baueinheiten enthält, welche die ganze mit Cuspidin und Låvenit verwandte Mineralgruppe auszeichnen: äoktaederwände", die vier Reihen breit sind und längsc verlaufen, sowie Si2O7-Gruppen. In Hjortdahlit II sind die Baueinheiten nach derselben Topologie wie in Låvenit verknüpft. Die besondere Verteilung der oktaedrisch koordinierten Kationen, die in der Arbeit bestimmt und diskutiert wird, ist für die Symmetrieerniedrigung nach P 1 verantwortlich.[▭
    Notes: Summary The crystal structure of Hiortdahlite II [triclinic P1,a = 11.012(6),b = 10.342(3),c = 7.359 (3) Å,a = 89.92(2)°, β = 109.21(5)°,y = 90.06(3)°], was determined and refined using 1793 reflections toR 1 = 0.069 and R2 = 0.066. The results of the structural study indicated that hiortdahlite II presents the modules which characterize the whole family of minerals related to cuspidine and låvenite, namely “octahedral walls”, four columns large and running alongc, and Si2O7 groups. In hiortdahlite II the modules are connected according to the same topology realized in låvenite. The peculiar octahedral cations distribution, which is determined and discussed in this work, is responsible for the descent in symmetry to P1.[▭
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01163156
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  • 3
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    Micrometeorites from the Transantarctic Mountains (2008)
    National Academy of Sciences
    Details
    Publication Date: 2008-11-14
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 4
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    Crystal-chemical study of ecdemite from Harstigen, a new natural member of the layered lead oxyhalides group (2019)
    Schweizerbart
    Details
    Publication Date: 2019
    Description: 〈span〉Ecdemite from Harstigen, Värmland, Central Sweden, was studied through Raman and FTIR spectroscopy, electron-microprobe techniques, synchrotron powder and single-crystal diffraction. The ideal mineral formula proposed by Palache, Pb〈sub〉6〈/sub〉Cl〈sub〉4〈/sub〉As〈sub〉2〈/sub〉O〈sub〉7〈/sub〉, is confirmed. In contrast to previous suggestions, however, the present study demonstrates that the mineral is monoclinic, with space-group type 〈span〉P〈/span〉2〈sub〉1〈/sub〉 and unit-cell parameters 〈span〉a〈/span〉 = 10.828(4) Å, 〈span〉b〈/span〉 = 10.826(2) Å, 〈span〉c〈/span〉 = 6.970(1) Å, β = 113.26°(2). The crystal-structural study of ecdemite shows that the mineral can be considered as made up of regularly alternating Cl layers and litharge-like defective layers, also hosting As cations, with the representative formula {Pb〈sub〉2〈/sub〉[Pb〈sub〉4〈/sub〉O](AsO〈sub〉3〈/sub〉)〈sub〉2〈/sub〉}〈sup〉4+〈/sup〉, in a 1:1 ratio. These features indicate that ecdemite can be considered as a new member of the layered lead oxyhalides group.〈/span〉
    Print ISSN: 0935-1221
    Electronic ISSN: 1617-4011
    Topics: Geosciences
    Published by Schweizerbart
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  • 5
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    Gabrielsonite revisited: crystal-structure determination and redefinition of chemical formula (2018)
    Schweizerbart
    Details
    Publication Date: 2018
    Description: 〈span〉A reinvestigation of gabrielsonite from the holotype specimen from Långban, central Sweden, using single-crystal synchrotron X-ray diffraction, electron-microprobe techniques and Fourier-transform infrared (FTIR) spectroscopy, Raman and Mössbauer spectroscopies show that the mineral is an anhydrous Fe〈sup〉3+〈/sup〉-bearing arsenite and not a hydrous Fe〈sup〉2+〈/sup〉-bearing arsenate, as originally proposed. The revised ideal chemical formula of gabrielsonite is PbFe〈sup〉3+〈/sup〉(As〈sup〉3+〈/sup〉O〈sub〉3〈/sub〉)O. The mineral is related to the descloizite supergroup, but it differs through the valencies of the non-Pb cations Fe (M〈sup〉3+〈/sup〉〈span〉vs.〈/span〉 M〈sup〉2+〈/sup〉) and As (3 + 〈span〉vs.〈/span〉 4 +) and through lower coordination of Pb (4 〈span〉vs.〈/span〉 7–8) and As (3 〈span〉vs.〈/span〉 4). The redefinition of gabrielsonite (proposal 17-G) has been approved by the Commission on New Minerals, Nomenclature and Classification (CNMNC) of the International Mineralogical Association.〈/span〉
    Print ISSN: 0935-1221
    Electronic ISSN: 1617-4011
    Topics: Geosciences
    Published by Schweizerbart
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  • 6
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    CRYSTAL CHEMISTRY OF MINERALS OF THE WOHLERITE GROUP FROM THE LOS ARCHIPELAGO, GUINEA (2012)
    Mineralogical Association of Canada
    Details
    Publication Date: 2012-06-01
    Description: As part of the SYNTHESYS European project, a suite of samples from the nepheline syenites of the Los Archipelago, Guinea, was studied in order to characterize the crystal chemistry of the minerals belonging to the wöhlerite group. Chemical and X-ray studies permitted the identification of four different mineral species: låvenite, normandite, wöhlerite, and hiortdahlite I. The identification of hiortdahlite II reported by Robles et al . (2001) seems to be questionable. Låvenite and normandite occur in the agpaitic suite, in association with analcime, catapleiite, fluorite, mosandrite, sérandite, sphalerite, and villiaumite; wöhlerite and hiortdahlite I are associated with britholite-(Ce), magnetite, titanite, and zircon. All the studied låvenite and normandite crystals are intermediate terms in the låvenite-normandite series. Wöhlerite shows the highest Mn content ever recorded for this species. Hiortdahlite I is the poorest in terms of both Zr and Na content and the richest in Ca and F among the known occurrences of "hiortdahlite". The crystal structures of these four phases were refined, with R factors ranging from 1.9% (for Mn-rich wöhlerite) to 7.3% (for hiortdahlite I). The wide range in Zr-Ti ratios observed in the låvenite-normandite series using new data and all available chemical data, not reported in other Zr-Ti minerals, seems to be related to the contemporaneous substitution of Mn by Ca. The comparison of the geometry of (Nb,Ti)- and Zr-centered polyhedra, including all the available structural studies of the wöhlerite group, indicates it is possible to make a distinction between (Nb,Ti)-dominant and Zr-dominant sites in this mineral family.
    Print ISSN: 0008-4476
    Topics: Geosciences
    Published by Mineralogical Association of Canada
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  • 7
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    Crystal-chemical study of ecdemite from Harstigen, a new natural member of the layered lead oxyhalides group (2019)
    Schweizerbart
    Details
    Publication Date: 2019
    Description: 〈span〉Ecdemite from Harstigen, Värmland, Central Sweden, was studied through Raman and FTIR spectroscopy, electron-microprobe techniques, synchrotron powder and single-crystal diffraction. The ideal mineral formula proposed by Palache, Pb〈sub〉6〈/sub〉Cl〈sub〉4〈/sub〉As〈sub〉2〈/sub〉O〈sub〉7〈/sub〉, is confirmed. In contrast to previous suggestions, however, the present study demonstrates that the mineral is monoclinic, with space-group type 〈span〉P〈/span〉2〈sub〉1〈/sub〉 and unit-cell parameters 〈span〉a〈/span〉 = 10.828(4) Å, 〈span〉b〈/span〉 = 10.826(2) Å, 〈span〉c〈/span〉 = 6.970(1) Å, β = 113.26°(2). The crystal-structural study of ecdemite shows that the mineral can be considered as made up of regularly alternating Cl layers and litharge-like defective layers, also hosting As cations, with the representative formula {Pb〈sub〉2〈/sub〉[Pb〈sub〉4〈/sub〉O](AsO〈sub〉3〈/sub〉)〈sub〉2〈/sub〉}〈sup〉4+〈/sup〉, in a 1:1 ratio. These features indicate that ecdemite can be considered as a new member of the layered lead oxyhalides group.〈/span〉
    Print ISSN: 0935-1221
    Electronic ISSN: 1617-4011
    Topics: Geosciences
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  • 8
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    Crystal structure study of a cobaltoan dolomite from Kolwezi, Democratic Republic of Congo (2015)
    International Union of Crystallography (IUC)
    Details
    Publication Date: 2015-02-22
    Description: A structural study has been undertaken on a cobaltoan dolomite, with chemical formula CaMg0.83Co0.17(CO3)2 (calcium magnesium cobalt dicarbonate), from Kolwezi, Democratic Republic of Congo. Pale-pink euhedral cobaltoan dolomite was associated with kolwezite [(Cu1.33Co0.67)(CO3)(OH)2] and cobaltoan malachite [(Cu,Co)2(CO3)(OH)2]. A crystal with a Co:Mg ratio of 1:5.6 (SEM/EDAX measurement), twinned on (11 -2 0) was used for crystal structural refinement. The refinement of the structural model of Reeder & Wenk [Am. Mineral. (1983), 68, 769–776; Ca at site 3a with site symmetry -3; Mg site at site 3b with site symmetry -3; C at site 6c with site symmetry 3; O at site 18f with site symmetry 1] showed that Co is totally incorporated in the Mg site, with refined occupancy Mg0.83Co0.17, which compares with Mg0.85Co0.15 from chemical data. The Co substitution reflects in the expansion of the cell volume, with a pronounced increasing of the c cell parameter.
    Keywords: crystal structuredolomitecobaltoanKolwezi
    Electronic ISSN: 1600-5368
    Topics: Chemistry and Pharmacology , Geosciences
    Published by International Union of Crystallography (IUC)
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  • 9
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    Parapierrotite from the Monte Arsiccio mine (Apuan Alps, Tuscany, Italy): occurrence and new data on its crystal-chemistry (2019)
    Schweizerbart
    Details
    Publication Date: 2019
    Description: 〈span〉A new finding of parapierrotite from the Monte Arsiccio mine, Apuan Alps, Tuscany, Italy, is reported here. Parapierrotite was identified in two different samples, as striated prismatic crystals, black in colour, ranging from 0.05 to 0.5 mm in length. In the studied specimens, parapierrotite is associated with sphalerite, zinkenite, tetrahedrite, and routhierite or with stibnite, protochabournéite, and routhierite. Chemical analysis indicated the presence of a Pb-bearing variety of parapierrotite; the electron microprobe data are (average of 15 spot analyses – in wt%): Tl 17.06(33), Pb 3.64(55), As 0.09(7), Sb 56.07(38), S 23.94(13), total 100.80(34). On the basis of ΣMe = 6 atoms per formula unit, the chemical formula of Pb-bearing parapierrotite from the Monte Arsiccio mine is Tl〈sub〉0.89(1)〈/sub〉Pb〈sub〉0.19(3)〈/sub〉(Sb〈sub〉4.91(13)〈/sub〉As〈sub〉0.01(1)〈/sub〉)〈sub〉Σ4.92〈/sub〉S〈sub〉7.96(36)〈/sub〉, ideally Tl〈sub〉0.9〈/sub〉Pb〈sub〉0.2〈/sub〉Sb〈sub〉4.9〈/sub〉S〈sub〉8〈/sub〉. Its crystal structure study gave a monoclinic unit cell, space group 〈span〉Pn〈/span〉, with 〈span〉a〈/span〉 = 8.1005(14), 〈span〉b〈/span〉 = 19.4385(9), 〈span〉c〈/span〉 = 9.0359(4) Å, β = 92.041(3)°, 〈span〉V〈/span〉 = 1421.9(3) Å〈sup〉3〈/sup〉, 〈span〉Z〈/span〉 = 4. The crystal structure was refined to 〈span〉R〈/span〉〈sub〉1〈/sub〉 = 0.046 on the basis of 10 461 reflections with 〈span〉F〈/span〉〈sub〉o〈/sub〉 〉 4σ(〈span〉F〈/span〉〈sub〉o〈/sub〉) and 265 refined parameters. Parapierrotite belongs to the pierrotite–parapierrotite homeotypic pair. The refinement of the crystal structure of this Pb-bearing variety allowed the description of the mechanism favouring the hosting of Pb in one of the two (010) walls of (Tl,Sb) atom pairs of this Tl sulfosalt.〈/span〉
    Print ISSN: 0935-1221
    Electronic ISSN: 1617-4011
    Topics: Geosciences
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  • 10
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    Crystal structure determination and Rietveld refinement of rosasite and mcguinnessite (2006)
    De Gruyter
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    Publication Date: 2006-06-01
    Print ISSN: 0930-486X
    Topics: Geosciences , Physics
    Published by De Gruyter
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