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  • 1
    Electronic Resource
    Electronic Resource
    The hydrogen bond system in natrochalcite-type compounds — an FTIR spectroscopic study of the H3O2 unit (1997)
    Springer
    Mineralogy and petrology 61 (1997), S. 223-235 
    Details
    ISSN: 1438-1168
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Zusammenfassung FTIR Spektroskopie wurde zur Untersuchung des Schwingungsverhaltens des Wasserstoff-Brückenbindungssystems der H302 Gruppe herangezogen, die mit stark variierenden O-H... 0 Abständen in Verbindungen des Natrochalcit-Typs, MeCu2(H3O2)(ZO4)2 (Me = Na, K; Z = S, Se) auftritt. Absorptionsbanden von Pulverund polarisierten Einkristallspektren nicht deuterierter und teilweise deuterierter Natrochalcit-Phasen, werden den Streck- und Knickschwingungen klar getrennter OH− und H2O Gruppen zugeordnet. Diese Ergebnisse weisen auf einen nichtzentrosymmetrischen Aufbau der H3O 2 − -Gruppe hin und bestätigen das Auftreten einer sehr starken Wasserstoffbrücke mit einer aufgespaltenen Position des Wasserstoffatoms.
    Notes: Summary FTIR spectroscopy was used to study the vibrational behaviour of the hydrogen bond system of the H3O2 unit, present with widely varying O-H...O distances in natrochalcite-type compounds, MeCu2(H3O2)(ZO4)2 (Me = Na, K; Z=S, Se). Absorption bands of powder and polarized single-crystal spectra of non-deuterated and partially deuterated natrochalcite phases are assigned to stretching and bending modes of clearly divided OH− and H2O groups. These results are indicative for a not centro-symmetric configuration of the H3O2 unit and confirm the presence of a very strong hydrogen bond with a split hydrogen atom position.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01172486
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  • 2
    Electronic Resource
    Electronic Resource
    A reflected light investigation of ruthenium (1986)
    Springer
    Mineralogy and petrology 35 (1986), S. 27-32 
    Details
    ISSN: 1438-1168
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Zusammenfassung Die Reflexionsspektren von Ruthenium wurden von 400 bis 700 nm mit polarisiertem Licht in Luft und in Öl für den ordentlichen und den außerordentlichen Strahl gemessen. Der Charakter der Bireflexion wechselt bei ca. 500 nm von negativ (bei kürzeren Wellenlängen) nach positiv. Die Absorptionskoeffizienten, Brechungsindizes und Absorptionskonstanten wurden berechnet, mit Literaturwerten verglichen und mit der HCP-Struktur von Ruthenium in Bezichung gesetzt.
    Notes: Summary The reflectance spectra of ruthenium were measured from 400 to 700 nm in air and in oil with polarized light for the ordinary and the extraordinary ray. The character of the bireflectance changes at about 500 nm from negative (at shorter wave lengths) to positive. Absorption coefficients, indices of refraction and absorption indices were calculated, compared to literature values and related to the HCP structure of ruthenium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01081916
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  • 3
    Electronic Resource
    Electronic Resource
    Precambrian blacksands as precursors of magnetite and Ilmenite bearing chlorite-micaschists, Bohemian Massif, Austria (1990)
    Springer
    Mineralogy and petrology 43 (1990), S. 147-160 
    Details
    ISSN: 1438-1168
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Zusammenfassung Eine Serie prdkambrischer Chlorit-Glimmerschiefer im Moravikum der Böhmischen Masse enthält bis zu 20 Vol.% feinkörnigen Magnetit und Ilmenit. Die Gesteine sind durch hohe Gehalte an Fe, Ti and V (durchschnittlich 13 Gew.%, 1.6 Gew.% und 200 ppm), die cine starke positive Korrelation untereinander aufweisen, charakterisiert. Die SiO2-Gehalte betragen ≈ 60 Gew.%; dies wird, gemeinsam mit relativ hohen K- und niedrigen Ca- und Mg-Werten, als Hinweis auf Metapelite und -psammite angesehen. Gelegentlich wurden reliktische Lagen von Magnetit und Chlorit, wie auch reliktische Titano-Magnetite beobachtet. Der Magnetit enthält bis zu jeweils 0.5 Gew.% V2O3 und Cr2O3, und bis zu t.2 Gew.% TiO, Die Ilmenite zeigen bis zu 5 Gew.% MnO. Die ungewöhnliche Gesamtzusammensetzung der Metasedimente, die reliktisch gebänderten Strukturen und die Zusammensetzung der Magnetite (verglichen mit Magnetiten verschiedenster Genese) legen einen klastisch-sedimentären Ursprung der, wahrscheinlich von einem basischen Magmatit abgetragenen, Erzminerale nahe. Folglich wird der Einfluß eines präkambrischen “Blacksands” im Ausgangsgestein vorgeschlagen und mit unterschiedlichen “Blacksands” aus der Literatur verglichen.
    Notes: Summary A complex of Precambrian chlorite-micaschists in the Moravian zone of the Bohemian massif contains up to 20 vol.% of fine grained magnetite and ilmenite. The rocks are characterized by high Fe, Ti and V contents (averages: 13 wt %, 1.6 wt% and 200 ppm), showing a strong positive correlation. SiO2 contents amount to 60 wt.%; together with relatively high K and low Ca and Mg values this is considered to be evidence for metapelites and -psammites. Relictic sedimentary layers of magnetite and chlorite, as well as relictic titano-magnetites were occasionally observed. Magnetite contains up to 0.5 wt.% V2O3 and Cr2O3 each, and up to 1.2 wt.% TiO2. Ilmenites show up to 5 wt.% MnO. The unusual bulk chemistry of the metasediments, the relictic layered structures and the composition of the magnetites (in relation to magnetites of different genesis) suggest a clastic sedimentary origin of the ore minerals, eroded probably from some basic magmatic complex. Hence a Precambrian black-sand is proposed as a precursor rock and compared with different blacksands known from the literature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01164308
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  • 4
    Electronic Resource
    Electronic Resource
    Optical anisotropy of zoned magnetites due to form birefringence (1995)
    Springer
    Mineralogy and petrology 52 (1995), S. 107-111 
    Details
    ISSN: 1438-1168
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Zusammenfassung Fünf Anschliffe von zonar gebauten Magnetiten aus Skarn-Lagerstätten zeigten unter dem Erzmikroskop optische Anisotropie-Erscheinungen, obwohl Röntgen-Pulverauf-nahmen kubischen Magnetit ergaben. Mittels hochauflösender Erzmikroskopie (Öl-Immersion, monochromatisches Licht) wurden extrem feine Zonierungen mit etwas unterschiedlichem Reflexionsvermögen beobachtet. Rasterelektronenmikroskopie (SEM) von angeätzten Proben bestätigte eine Zonendicke zwischen einigen Yin und 100 nm. EDX Analysen zeigten Unterschiede in der Zusammensetzung dieser Zonen, die von fast reinem Magnetit bis zu CaO-, MgO-, A12O3-, SiO2-Gehalten von insgesamt 4 Gew.% reichen. Offensichtlich fiihren die extrem diinnen, parallelen Zonierungen mit unterschiedlicher Zusammensetzung, und folglich unterschiedlichen optischen Konstanten (Reflexion, Absorption, Lichtbrechung) zu optischer Anisotropie durch Formdoppelbrechung.
    Notes: Summary Five polished samples of zoned magnetites from skarn deposits showed optical anisotropy effects under the ore microscope, though X-ray powder diffraction investigations indicated cubic magnetite. Using high magnification ore microscopy (oil immersion lenses, monochromatic light), extremely fine zones with slightly different reflectivity were observed. Scanning electron microscopy (SEM) of etched samples confirmed zones with a thickness between a few μm and 100 nm. EDX analyses showed differences in the composition of these zones, ranging from almost pure magnetite to contents of CaO, MgO, A12O3, SiO2 up to 4 wt.% in total. Thus, the extremely thin, parallel zones of magnetite, with slightly different compositions and different optical constants (reflectivity, absorption, refraction), obviously lead to optical anisotropy due to form birefringence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01163129
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  • 5
    Electronic Resource
    Electronic Resource
    Crystal chemistry and optics of bazzite from Furkabasistunnel (Switzerland) (1995)
    Springer
    Mineralogy and petrology 52 (1995), S. 113-126 
    Details
    ISSN: 1438-1168
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Zusammenfassung Die Kristallstruktur eines blauen Bazzits (Raumgruppe P6/mcc, Z = 2,a = 9.501(1),c = 9.178(1) Å) mit der Zusammensetzung Be3(Sc1.25Fe3+ 0.43Mg0.32Mn0.03Al0.02)Σ2=2.05 Si6)O18[Na0.32(n H2O)] wurde von Röntgeneinkristalldaten mit 422 Reflexen zu R = 2.2% verfeinert. Die Struktur ist die des Berylltyps mit der Besonderheit, daß die Oktaeder entlang der c-Achse stark zusammengedrückt sind. Die oktaedrischen Me-O Abstände im Bazzit betragen 2.080 Å, im Gegensatz zu 1.904Å im Beryll. Die Stauchung der Oktaeder im Bazzit führt zu einer längeren a-Achse als im Beryll (9.209 Å). Zweiwertige Kationen (vor allem Mg) in oktaedrischer Koordination werden durch Na auf (0, 0, 0), in den strukturellen Kanalen, neutralisiert. Polarisierte Einkristall-IR-Spektren zwischen 400 and 8000 cm−1 zeigen, daß H2O Moleküle in den strukturellen Kanalen mit dem H-H Vektor senkrecht zur c-Achse orientiert sind. Die IR-Spektren weisen außerdem mehr Absorptionsbanden auf, als für den H2O Typ II bekannt sind, sodaß entweder mehr als eine H2O Spezies oder sogar OH-Gruppen sehr wahrscheinlich sind. Brechungsindizes am gleichen Bazzit wurden auf einem Spindeltisch mit der Wellenlängen-Temperatur Variationsmethode gemessen und ergaben no = 1.6279(3), ne = 1.6066(5) bei 589 nm und 25 °C. Die Doppelbrechung A = 0.0210 ist deutlich höher als für einen nahezu Endgliedberyll (A = 0.0047). Diese hohe Doppelbrechung des Bazzits wird durch die elektronische Polarisierbarkeit von oktaedrischem Sc und Fe verursacht, die no starker ansteigen läßt als ne. Übergangselemente im Bazzit sind auch für die höhere Dispersion der Brechungsindizes als im Beryll verantwortlich.
    Notes: Summary The crystal structure of blue bazzite (space group P6/mcc, Z = 2, α = 9.501(1),c = 9.178(1) Å) with the composition Be3(Sc1.25Fe3+ 0.43Mg0.32Mn0.03Al0.02)Σ=2.05 Si6O18[Na0.32(n H2O)] was refined from X-ray single-crystal data with 422 unique reflections to R = 2.2%. The structure is of the beryl type with octahedra strongly compressed parallel to the c-axis. The octahedral Me-O distance in bazzite is 2.080 A compared to 1.904 Å in beryl. The flattening of octahedra leads to a larger a cell dimension in bazzite compared to beryl (9.209 A). Two-valent cations (mainly Mg) in octahedral coordination are charge balanced by Na at (0, 0, 0) in the structural channels. Polarized single-crystal IR-spectra recorded between 400 and 8000 cm−1 indicate that H2O in the structural channels is oriented with the H-H vector perpendicular to thec-axis. The IR-spectra show more absorption bands than known for type II H2O in beryl thus the existence of more than one H2O species or even OH-groups is very likely. Refractive indices of the same bazzite were measured using a spindle-stage and employing the wavelength-temperature variation method yielding no = 1.6279(3), ne = 1.6066(5) for 589 nm at 25°C. The birefringence Δ = 0.0213 is significantly larger than the one of near end-member beryl (Δ = 0.0047). This high birefringence of bazzite is related to the electronic polarizability of octahedral Sc and Fe which increase no at a stronger rate than ne. Transition metals in bazzite are also responsible for a higher refractive index dispersion than found for beryl.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01163130
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  • 6
    Electronic Resource
    Electronic Resource
    Jankovićite, Tl5Sb9(As, Sb)4S22, a new TI-sulfosalt from Allchar, Macedonia (1995)
    Springer
    Mineralogy and petrology 53 (1995), S. 125-131 
    Details
    ISSN: 1438-1168
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Zusammenfassung Ein bislang unbekanntes Thallium-Antimon-Arsen-Sulfosalz wurde mittels Erzmikroskopie (inklusive quantitativer Reflexionsmessungen) und Elektronenstrahl-Mikrosonde in Proben aus der TI-Sb-As-Sulfid-Lagerstätte Allchar in Macedonien entdeckt. Die chemische Formel lautet Tl5Sb9(As,Sb)4S22, aus Röntgen-Einkristallaufnahmen und Pulverdiffraktogrammen konnten folgende Gitterkonstanten bestimmt werden: ao = 7.393(4) Å, bo = 8.707(2) _Å, co = 17.584(3) Å, a = 103.81(1)°, β = 91.79(1)°, γ = 109.50(1)°; Raumgruppe $$P\bar 1$$ , Z = 1. Das neue Mineral, sowie der neue Mineralname “Jankovićit” wurden durch die IMA/CNMMN anerkannt.
    Notes: Summary A hitherto unknown TI-sulfosalt, containing antimony and arsenic, was discovered by ore microscopy (including quantitative reflectance measurements) and electron microprobe analysis in samples from the Allchar TI-Sb-As sulfide ore deposit (Macedonia). The chemical formula is TI5Sb9(As,Sb)4S22, X-ray single crystal and powder diffration data gave the lattice parametersα o = 7.393(4) Å, b0 = 8.707(2) Å, co = 17.584(3) Å,α = 103.81(1)°,β = 91.79(1)°,γ = 109.50(1)°; space group $$P\bar 1$$ , Z = 1. The new mineral and the new mineral naine “jankoviéite” have been approved by the IMA/CNMMN.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01171951
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  • 7
    Electronic Resource
    Electronic Resource
    “Dreieck”, a simple BASIC-program for plotting triangular concentration diagrams on IBM (XT/AT)-compatible personal computer systems (1990)
    Springer
    Mineralogy and petrology 41 (1990), S. 257-258 
    Details
    ISSN: 1438-1168
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01168499
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  • 8
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    The origin of black colouration in onyx agate from Mali (2012)
    Mineralogical Society of Great Britain and Ireland
    Details
    Publication Date: 2012-02-01
    Description: Natural onyx agate from Mali was investigated in an integrated mineralogical and chemical study to reveal the origin of the unusual black colouration. Detailed studies by polarizing microscopy, scanning electron microscopy and micro-Raman spectroscopy showed that the colour of the dark bands is related to the incorporation of small particles of carbon (low-crystalline graphite) up to 200 nm in size into the cryptocrystalline silica matrix. The dark bands have carbon contents of 1.88 wt.%. The location of the graphite particles is closely related to the primary structural banding in the chalcedony. Cathodoluminescence data shows that the banding is interrupted by small fissures containing secondary hydrothermal quartz. The carbon isotope composition (d13C value of -31.1±0.2‰) of the carbonaceous material points to an organic precursor. Both the direct hydrothermal formation of graphite from methane under elevated temperature and the graphitization of organic precursors by secondary hydrothermal or metamorphic overprint are possible explanations for the colour of the dark bands. The graphitization of organic precursors results in an intense electron spin resonance line at geff = 2.0026.
    Print ISSN: 0026-461X
    Electronic ISSN: 1471-8022
    Topics: Geosciences
    Published by Mineralogical Society of Great Britain and Ireland
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  • 9
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    Perettiite-(Y), Y3+2Mn2+4Fe2+[Si2B8O24], a new mineral from Momeik, Myanmar (2015)
    Schweizerbart
    Details
    Publication Date: 2015-12-02
    Description: The new mineral perettiite-(Y), end-member formula Y 3+ 2 Mn 2+ 4 Fe 2+ [Si 2 B 8 O 24 ], from pegmatites in the region of Momeik, north of Mogok, Myanmar, occurs as yellow needles enclosed in phenakite crystals. The mineral was named after the mineralogist and gemologist Dr. Adolf Peretti. The empirical formula using LA-ICP-MS data (based on 24 O pfu ) is Y 2.06 Ln 0.53 Zr 0.02 Th 0.01 Mn 3.24 Ca 0.38 Fe 0.71 Mg 0.07 Al 0.11 Li 0.22 Si 1.95 B 7.44 Be 0.31 O 24 . Calculation of the H 2 O content using IR absorption data yields a maximum hydroxyl/water content equivalent to 0.1 wt.% H 2 O. The strongest lines in the powder pattern [ d in Å ( I meas. ) ( hkl )] are 4.63 (52) (010), 4.08 (28) (301, 103), 3.74 (20) (210), 3.05 (100) (113, 311, 303), 2.64 (67) (410, 014), 2.54 (60) (313), 2.12 (23) (600, 006), 1.87 (33) (420, 024), 1.84 (52) (415, 323), 1.57 (20) (026, 620), 1.44 (25) (133, 331). The perettiite-(Y) crystals show a tetragonal X-ray diffraction pattern but the structure could only be solved as a 50/50 pseudo-merohedral orthorhombic twin with the a and c axes having the same length. The structure, refined to R 1 = 0.017 (space group Pmna with a = 12.8252(5), b = 4.6187(2), c = 12.8252(5) Å, V = 759.71(5) Å3, Z = 2), is characterized by two eight-coordinated sites: one dominated by Y and lanthanoids (Ln) and the other by Mn 2+ (with additional Ca 2+ and Y 3+ ). An octahedral site is occupied by (Fe 2+ , Mg) with additional Li + . These cation sites form an interlayer between two tetrahedral sheets of Si 2 B 8 O 24 composition. Boron shows minor replacement by beryllium. Arrangement of 4-, 5- and 8-membered rings within (010) form the borosilicate tetrahedral sheets. Perettiite-(Y) is brittle, with irregular fracture and (010) cleavage; the estimated Mohs hardness is ~ 7. Using the empirical formula, the density was estimated to be 4.533 g cm –3 . Perettiite-(Y) is biaxial, α = 1.82(1), = 1.84(1) (589 nm).
    Print ISSN: 0935-1221
    Electronic ISSN: 1617-4011
    Topics: Geosciences
    Published by Schweizerbart
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  • 10
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    The origin of black colouration in onyx agate from Mali (2012)
    Mineralogical Society of Great Britain and Ireland
    Details
    Publication Date: 2012-02-01
    Description: Natural onyx agate from Mali was investigated in an integrated mineralogical and chemical study to reveal the origin of the unusual black colouration. Detailed studies by polarizing microscopy, scanning electron microscopy and micro-Raman spectroscopy showed that the colour of the dark bands is related to the incorporation of small particles of carbon (low-crystalline graphite) up to 200 nm in size into the cryptocrystalline silica matrix. The dark bands have carbon contents of 1.88 wt.%. The location of the graphite particles is closely related to the primary structural banding in the chalcedony. Cathodoluminescence data shows that the banding is interrupted by small fissures containing secondary hydrothermal quartz. The carbon isotope composition (d13C value of -31.1±0.2‰) of the carbonaceous material points to an organic precursor. Both the direct hydrothermal formation of graphite from methane under elevated temperature and the graphitization of organic precursors by secondary hydrothermal or metamorphic overprint are possible explanations for the colour of the dark bands. The graphitization of organic precursors results in an intense electron spin resonance line at geff = 2.0026.
    Print ISSN: 0026-461X
    Electronic ISSN: 1471-8022
    Topics: Geosciences
    Published by Mineralogical Society of Great Britain and Ireland
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