Sphaeromorphic algal cysts, most probably of the prasinophyte Tasmanites, and acanthomorphic acritarch vesicles, most probably Solisphaeridium, occur in a single 20 cm thick bed of micritic limestone in the lower part of the Middle Devonian (Givetian) Tully Formation near Lock Haven, Pennsylvania. Specimens are composed of authigenic calcite and pyrite crystals about 5–10 μm in length. Some spe...

Well-shaped single crystals of binary AuSn2 were obtained as a side product during the synthesis of LiAu3Sn4. The structure of AuSn2 has been studied by X-ray diffractometer data: Pbca, Z = 8, a = 689.8(1), b = 701.1(1), c = 1177.3(2) pm, wR2 = 0.0533, 1234 F2 values, and 29 variables. The gold atoms show a distorted octahedral coordination by tin at Au–Sn distances ranging from 272 to 283 pm. ...

Os minerais naturais pirita e chalcopirita tem sido usados como sensores em eletrodos indicadores usando acetronitrila e propionitrila como solventes. Os resultados mostram vantagens excepcionais da pirita e chacopirita como sensores eletroquímicos e também a possibilidade de aplicação desses eletrodos para determinações em solventes não aquosos onde eletrodos de vidro mostram dificuldades. O c...

This study investigates removing ash and pyrite sulphur from bitumen by column flotation process. Central composite design (CCD) of response surface methodology (RSM) was applied for modeling and optimization of the percentage of ash and pyrite sulphur removal from bitumen. The effects of five parameters namely the amounts of collector and frother agents, particle size, wash water rate and feed...

We investigate sub-bandgap absorption in pyrite FeS 2 single-crystals, using both natural and synthetic crystals. Both types of crystals show non-negligible magnitudes of sub-bandgap absorption. To test whether the origin of the residual sub-bandgap absorption is partially due to a lower bulk bandgap than previously thought, we conduct temperature-dependent electrical measurements on natural an...

Five acidophilic protozoa (three flagellates, one ciliate and one amoeba) were isolated from acid mine water and a coal biotreatment plant, and grown in mixed cultures with acidophilic bacteria. Cultures were routinely maintained in ferrous sulphate media: in media containing pyrite or pyritic coal, protozoa grew in cultures containing coarse-grain (61-200 pm) but not fine-grain (c 61 pm) miner...

The mineralogic residence and abundance of trace metals is an important environmental issue. Data from the USGS coal quality database show that potentially toxic elements, includingHg, As,Mo, Se, Cu, and Tl are enriched in a subset of coal samples in the BlackWarrior Basin of Alabama, USA. Although the coal as-mined typically is low in these elements, localized enrichments occur in high-pyrite ...

Abstract: Nanoscale FeS2 was synthesized via a simple hydrothermal method and was decorated by hydrothermal carbonization (FeS2@C). The structural properties of the synthesized materials detected by X-ray diffraction (XRD), together with the morphologies characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that the hydrothermal carbonization o...

The study of chemical composition of waters in the abandoned open pyrite mine at WieSciszowice (the Rudawy Janowickie Mts., the W Sudetes, SW Poland) has been canied out with the aim of detennining the conditions of mobi1i7..ation and solubility of aluminium. Both the ion activities and the saturation of water samples with respect to mineral phases have been calculated using the WATEQ4F compute...

Ultrahigh-pressure phase boundary between solid and liquid SiO2 is still quite unclear. Here we present predictions of silica melting curve for the multimegabar pressure regime, as obtained from first principles molecular dynamics simulations. We calculate the melting temperatures from three high pressure phases of silica (pyrite-, cotunnite-, and Fe2P-type SiO2) at different pressures using th...