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International Journal of Geosciences
Number of Followers: 9

This is an Open Access Journal

Open Access journal
ISSN (Print) 2156-8359 - ISSN (Online) 2156-8367
Published by Scientific Research Publishing

[243 journals]

A word of the Editor-in-Chief
- Abstract: Plášil JK; Vol. 66, issue 3, page: 137
Ferraioloite from the Sítio do Castelo mine, Folgosinho (Guarda,
Portugal), description and Raman spectroscopy
- Abstract: Tvrdý J, Sejkora J, Rosseel P, Dolníček Z; Vol. 66, issue 3, pages 139 - 146
  A zinc phosphate corresponding to ferraioloite with low Mg and high Na cation contents in interlayer space was identified in samples from the Sítio do Castelo mine, Folgosinho (Guarda, Portugal). It occurs as sky-blue, pearly lustrous, radial or irregular aggregates up to 1 mm in size composed of very thin elongated flaky crystals. The mineral is monoclinic, space group I2/m, with unit-cell parameters refined from X-ray powder diffraction data: a = 25.417(7), b = 6.342(4), c =15.186(5) Å, β = 90.02(4)°, V = 2448.0(17) Å3. The chemical composition generally agrees with published data for ferraioloite, but differs significantly in elements present at sites assumed to be in the interlayer of the crystal structure. The corresponding empirical formula based on 8 (PO)4 and 4 (OH) groups pfu is (Mg0.16Na0.15Ca0.09K0.01)Σ0.41 Mn4.22(Fe2+1.64Fe3+1.15Al1.47)Σ4.26 Zn3.87(PO4)8(OH)4(H2O)20. The Raman spectra and tentative assignment of observed bands are given. The most prominent bands are attributed to stretching and bending vibrations of phosphate tetrahedra and complex metal-centered polyhedra. Bands of O-H stretching vibrations are weak, and bending vibrations of water molecules were not observed. The origin of the mineral is related to in-situ supergene weathering of zwieselite-triplite and isokite-fluorapatite assemblages with admixtures of sphalerite.
Rapidcreekite of anthropogenic origin - ’korkinoite’ from burnt mine
dump in the Chelyabinsk coal basin, South Urals, Russia: crystal structure
refinement, thermal behavior and spectroscopic characterization
- Abstract: Avdontceva MS, Zolotarev AA, Krivovichev SV, Krzhizhanovskaya MG, Bocharov VN, Shilovskikh VV, Zolotarev AA, Rassomakhin MA; Vol. 66, issue 3, pages 147 - 156
  Anthropogenic rapidcreekite, Ca2(SO4)(CO3)·4H2O, from burnt dumps of coal mines in the Chelyabinsk coal basin, South Urals, Russia, previously described as ’korkinoite’, has been studied by single-crystal X-ray diffraction, high-temperature powder X-ray diffraction, infrared (IR) and Raman spectroscopy. The mineral is orthorhombic, Pcnb, a = 15.5334(6) Å, b = 19.2379(7) Å, c = 6.1625(3) Å, V = 1841.54(13) Å3. The crystal structure is based upon heteropolyhedral sheets parallel to (100) and can be described as produced from the crystal structure of gypsum by chemical twinning. The Ca1 and Ca2 sites are coordinated by six O atoms and two H2O molecules each. The CaO8 polyhedra form chains parallel to the с axis, connected via CO3 groups and SO4 tetrahedra to form a two-dimensional arrangement. The sheets are linked to each other by means of the hydrogen bonding network. The main bands of the IR and Raman spectra correspond to symmetric and asymmetric vibrations in the SO42- tetrahedra and CO32- groups. The OH- stretching region possesses high-intensity peaks. ’Korkinoite’ is stable up to 200 °C. Thermal expansion has a strong anisotropic character in the ab and bc planes and is almost isotropic within the ac plane. The thermal expansion coefficients are approximately the same at room temperature and 200 °C (×10-6 °C-1): (αa = 53.7, αb = 11.6, αc = 52.0, αv = 117.3 (25 °C); αa = 53.2, αb = 11.6, αc = 51.6, αv = 116.4 (200 °C)). The maximal thermal expansion is along [100] (perpendicular to the plane of the layers). Both ’korkinoite’ (anthropogenic rapidcreekite) and rapidcreekite are structurally related to gypsum due to the unit-cell twinning induced by replacing one-half of sulfate groups in gypsum by carbonate ions in rapidcreekite. These structural relations determine the similarity of thermal behavior of gypsum and rapidcreekite with strongly anisotropic expansion within the sheet of Ca polyhedra and sulfate or sulfate and carbonate groups. The current study confirms that ’korkinoite’ is identical to rapidcreekite, except for the insignificant differences in the chemical composition.
Bismuth, lead-bismuth and lead-antimony sulfosalts from the granite-hosted
hydrothermal quartz veins at the Elisabeth mine, Gemerská Poloma,
Spišsko-gemerské rudohorie Mts., Slovakia
- Abstract: Števko M, Sejkora J; Vol. 66, issue 3, pages 157 - 173
  An interesting assemblage of bismuth and complex lead-bismuth and lead-antimony sulfosalts have been identified in samples from hydrothermal quartz veins hosted in S-type granitic rocks at the Elisabeth mine near Gemerská Poloma, Slovakia. We provide the first detailed study of the chemical composition of sulfosalts from the hydrothermal veins directly related to the specialized (Sn-W-F enriched) Gemeric granites. Bismuthinite derivates (bismuthinite and phases with naik ranging from 21.3 to 23.7 and 30.3), minerals of the kobellite-tintinaite series (with Sb/(Sb+Bi) atomic ratio ranging considerably between 0.13 and 0.71), giessenite-izoklakeite series (with Sb/(Sb+Bi) from 0.26 to 0.33) as well as Pb-Sb sulfosalts (mainly jamesonite, boulangerite, robinsonite and their Bi-rich varieties) are common. Rare Bi-enriched rouxelite, bournonite and minerals of the tetrahedrite group were also observed. The two distinct types of sulfosalts associations were distinguished, each related to the different type of host rock and with variable Bi/Sb ratio. The first is represented predominantly by Bi-rich sulfosalts (bismuthinite derivates, kobellite, giessenite-izoklakeite) and occurs in the quartz veins hosted in P-enriched leucogranite. The second association is developed only in hydrothermal quartz veins hosted in porphyric granites and except of Bi (bismuthinite derivates) also significant amounts of Sb-rich sulfosalts (tintinaite, boulangerite, robinsonite, jamesonite, rouxelite, bournonite and tetrahedrite-(Zn) to tetrahedrite-(Fe)) are present.
Crystal structure of undersubstituted Sb-rich vikingite Vik40,
Ag2.85Pb12.35(Bi9.52Sb1.27)Σ=10.80S30: site population and comparison
with structure of vikingite Vik50, Ag3.5Pb11.0Bi11.5S30
- Abstract: Pažout R, Dušek M; Vol. 66, issue 3, pages 175 - 184
  Crystal structure of Sb-rich vikingite with lillianite substitution percentage L% below 50 % from Kutná Hora ore district, Czech Republic, was solved and refined from single-crystal diffraction data to determine the site populations of metal sites concerning a) the decreasing “lillianite“ substitution 2 Pb2+ = Ag+ + Bi3+; b) Sb content not known in vikingite from other localities throughout the world. Vikingite is monoclinic, C2/m, with a = 13.5394(10), b = 4.0992(3), c = 25.506(3) Å, β = 95.597(8)°, V = 1408.9(2) Å3, Z = 1, Dc = 7.0412 g/cm3. The structural formula derived from the refinement is Ag2.85Pb12.35(Bi9.52Sb1.27)Σ=10.80S30, corresponding to Vik40.0. The structure of vikingite is composed of thinner slabs (4L) of four octahedra Me2-Me1-Me1-Me2 and thicker slabs (7L) of seven octahedra Me4-Me5-Me6-Me7-Me6-Me5-Me4 separated by Pb atoms Me3 in trigonal prismatic coordination. The refinement showed differences between the structures of Vik40 and the previously published structure of Vik50. The drop of L% below 50 % shows most profoundly in the marginal octahedral site Me2 of the thinner 4L slabs, which becomes a Bi-Pb-Ag site with 28.6 % of silver next to 50 % of Bi and 21.4 % of Pb. The central Me1 site from 4L slabs which is almost a pure Bi site in Vik50 (0.97 Bi + 0.3 Ag) becomes a Bi-Pb site with minor Sb (0.54 Bi + 0.06 Sb + 0.40 Pb) in Vik40. The Sb for Bi substitution was found to take place in the semimarginal site Me5 (0.74 Bi + 0.26 Sb) in the thicker 7L slabs, which is a pure Bi site in Sb-free Vik50. Another important change against Vik50 occurs in central octahedral site Me6 (pure Pb site in Vik50), which becomes despite the decrease in Bi content with decreasing L%, a Pb-Bi mix site. The correctness of the refined structural model was verified and the occupancies of mixed sites were fine-tuned employing charge distribution calculations in program ECoN21. In Vik40 weighted average bond lengths RAV of the marginal sites Me2 and Me4 and of the central site Me1 are significantly larger than in Vik50, reflecting the lower Ag content and the presence of Pb, while the Bi site Me5, which is partly substituted by Sb and the site Me6 with minor Bi at the expense of Pb exhibit adequately shortened RAV values.

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