Ammonioalunite, ammoniojarosite and their solid-solution series found on a burning coal dump at Czerwionka, Upper Silesian Coal Basin, Poland, were examined using powder X-ray diffraction, electron probe microanalysis, inductively coupled plasma mass spectrometry, infrared spectroscopy and thermal analysis methods. The minerals occur as yellow, fine-grained crusts and botryoidal masses in the outer part of a sulphate crust found ∼1 m below the surface. The crust is composed mainly of godovikovite and tschermigite that formed by interaction of sour fire gases or solutions and waste materials beneath the surface of the burning coal dump at temperatures of at least 80—100°C. The crystals often reveal oscillatory zoning due to different Al and Fe contents in thin bands, from near end-members to extensive solid solutions. Our analyses suggest the existence in nature of a complete solid solution between ammonioalunite and ammoniojarosite. They also carry essential amounts of chlorine.

ABSTRACT:Parafiniuk, J., Siuda, R. and Borkowski, A. 2016. Sulphate and arsenate minerals as environmental indicators in the weathering zones of selected ore deposits, Western Sudetes, Poland. Acta Geologica Polonica, 66 (3), 493-508. Warszawa.The results of a complex investigation of the sulphate and arsenate assemblages forming in the weathering zone of selected ore deposits in the Sudetes are presented. The development of the weathering zone has been characterised in the polymetallic ore deposits at Miedzianka-Ciechanowice and Radzimowice, and the pyrite deposit at Wieściszowice, which differ in the chemical compositions of the ore and barren minerals and the hydrological conditions. Secondary sulphate and arsenate mineral assemblages vary significantly among the ore deposits under study. Their crystallization is discussed, taking into consideration the stability of particular minerals and the paths of their transformation. It is shown that these minerals have great potential as indicators of weathering processes. A significant role for microorganisms in the formation of the weathering zone of the ore deposits under study is also proven.

X-ray diffraction studies of crystals under pressure and quantitative experimental charge density analysis are among the most demanding types of crystallographic research. A successful feasibility study of the electron density in the mineral grossular under 1 GPa pressure conducted at the CRISTAL beamline at the SOLEIL synchrotron is presented in this work. A single crystal was placed in a diamond anvil cell, but owing to its special design (wide opening angle), short synchrotron wavelength and the high symmetry of the crystal, data with high completeness and high resolution were collected. This allowed refinement of a full multipole model of experimental electron distribution. Results are consistent with the benchmark measurement conducted without a diamond-anvil cell and also with the literature describing investigations of similar structures. Results of theoretical calculations of electron density distribution on the basis of dynamic structure factors mimic experimental findings very well. Such studies allow for laboratory simulations of processes which take place in the Earth's mantle.

On the basis of a multipole refinement of single-crystal X-ray diffraction data collected using an Ag source at 90 K to a resolution of 1.63 Å, a quantitative experimental charge density distribution has been obtained for fluorite (CaF). The atoms-in-molecules integrated experimental charges for Ca and F ions are +1.40 e and -0.70 e, respectively. The derived electron-density distribution, maximum electron-density paths, interaction lines and bond critical points along Ca...F and F...F contacts revealed the character of these interactions. The Ca...F interaction is clearly a closed shell and ionic in character. However, the F...F interaction has properties associated with the recently recognized type of interaction referred to as `charge-shift' bonding. This conclusion is supported by the topology of the electron localization function and analysis of the quantum theory of atoms in molecules and crystals topological parameters. The Ca...F bonded radii - measured as distances from the centre of the ion to the critical point - are 1.21 Å for the Ca cation and 1.15 Å for the F anion. These values are in a good agreement with the corresponding Shannon ionic radii. The F...F bond path and bond critical point is also found in the CaF crystal structure. According to the quantum theory of atoms in molecules and crystals, this interaction is attractive in character. This is additionally supported by the topology of non-covalent interactions based on the reduced density gradient.

No abstract

Stable isotope ((13)C, (18)O, (34)S) and trace element (Sr(2+), Mg(2+), Mn(2+), Ba(2+), Na(+)) investigations of elemental sulfur, primary calcites and mixtures of aragonite with secondary, post-aragonitic calcite from sulfur-bearing limestones have provided new insights into the geochemistry of the mineral forming environment of the native sulfur deposit at Machów (SE-Poland). The carbon isotopic composition of carbonates (δ(13)C = -41 to -47‰ vs. PDB) associated with native sulfur (δ(34)S = + 10 to + 15‰ vs. V-CDT) relates their formation to the microbiological anaerobic oxidation of methane and the reduction of sulfate derived from Miocene gypsum. From a comparison with experimentally derived fractionation factors the element ratios of the aqueous fluids responsible for carbonate formation are estimated. In agreement with field and laboratory observations, ratios near seawater composition are obtained for primary aragonite, whereas the fluids were relatively enriched in dissolved calcium during the formation of primary and secondary calcites. Based on the oxygen isotope composition of the carbonates (δ(18)O = -3.9 to -5.9‰ vs. PDB) and a secondary SrSO(4) (δ(18)O = + 20‰ vs. SMOW; δ(34)S = + 59‰ vs. V-CDT), maximum formation temperatures of 35°C (carbonates) and 47°C (celestite) are obtained, in agreement with estimates for West Ukraine sulfur ores. The sulfur isotopic composition of elemental sulfur associated with carbonates points to intense microbial reduction of sulfate derived from Miocene gypsum (δ(34)S ≈ + 23‰) prior to the re-oxidation of dissolved reduced sulfur species.

Page s193 s193 Upon complex thermolysis in hydrogen the nanoalloy Pd 0.5 Rh 0.5 is formed (Fm-3m space group, a = 3.847 Å). The thermolysis final temperature is 400 ºC, the average particle size is 20 nm.

Newly discovered assemblages of numerous ore minerals disseminated in schists, amphibolites and mylonites at their contacts with a dolomite lens exploited at Rędziny, in the northeastern Bohemian Massif, Western Sudetes, Poland, was used in an evaluation of the thermochemical conditions under which specific, and in some cases rare, phases formed. Arsenopyrite, cassiterite and associated base-metal sulfides crystallized at temperatures lower than 550°C. The Ag-bearing sulfosalts pavonite, benjaminite, makovickyite, gustavite, berryite, matildite, giessenite, izoklakeite, cosalite, freibergite and tetrahedrite crystallized along with Ag-bearing galena in the temperature range ca. 350-280°C. They preceded the Cu-Pb-Bi(Sb) sulfosalts wittichenite, bournonite, aikinite-group minerals, emplectite and Ag-poor tennantite, which crystallized from about 300°C to even below 200°C. Kësterite and černýite crystallized at temperatures about 350°C, černýite occurring only in Zn-depleted environments. Ferrokësterite and petrukite, occurring with Zn-enriched chalcopyrite as inclusions within (Fe,Cd,Cu,Sn)-enriched sphalerite, are products of decomposition at 340-270°C of a higher-temperature (Zn,Cd,Cu,Fe,Sn) sulfide. Chatkalite formed as a metastable phase at the SnO 2 -SnS equilibrium at temperatures of about 270-260°C; stannoidite crystallized from 270°C to 250-240°C, at which point mawsonite began to crystallize. Unknown Sn-bearing sulfides, with compositions varying between Cu 4 Fe 3 SnS 8 and Cu 10 SnS 8 , crystallized at probably still lower temperatures. Bismuth sulfides (bismuthinite and an unknown Pb-Bi-S phase), sulfoselenides (ikunolite) and sulfotellurides (tetradymite, joséite-A, joséite-B and an unknown Bi-Te-S phase) crystallized under varying conditions: tetradymite at about 300°C, ikunolite at 270-240°C, bismuthinite from about 300 to 220°C, and joséite-A and joséite-B clearly below 240°C. SOmmAIRENous utilisons les assemblages de plusieurs minéraux de minerais disséminés dans les schistes, les amphibolites et les mylonites au contact avec une lentille de dolomite exploitée à Rędziny, dans le secteur nord-est du massif Bohémien, Sudètes occidentales, Pologne, pour évaluer les conditions thermochimiques régissant les conditions de formation de ces minéraux, dont quelques-uns sont assez rares. L'arsénopyrite, la cassitérite et les sulfures des métaux de base associés ont cristallisé à une température inférieure à 550°C. Les sulfosels argentifères pavonite, benjaminite, makovickyite, gustavite, berryite, matildite, giessenite, izoklakeïte, cosalite, freibergite et tétraédrite ont cristallisé avec la galène argentifère dans l'intervalle ca. 350-280°C. Ces minéraux ont précédé les sulfosels à Cu-Pb-Bi(Sb) wittichenite, bournonite, minéraux du groupe de l'aikinite, emplectite et tennantite à faible teneur en Ag, qui ont cristallisé entre environ 300°C jusqu'à même moins de 200°C. La kësterite et la černýite ont cristallisé à environ 350°C, la černýite étant limitée aux milieux dépourvus de Zn. La ferrokësterite et la p...