Volume 46 (2015): Issue 1-2 (June 2015)

In the Permian rhyodacite quarry at Zalas near Krakow, southern Poland, thallium-bearing Mn oxides occur in a small fault zone cutting Middle Jurassic sandy limestone poorly encrusted by an oxidized polymetallic mineralization. The encrustation comprises sulphides (pyrite, chalcopyrite, chalcocite, covellite, galena, marcasite), native bismuth, hematite, goethite, cuprite, mottramite, iodargyrite, unrecognized Cu sulphates and Bi oxychlorides as supergene minerals, barite and rare tiny grains of gold. It is most likely connected with rejuvenation of Early-Paleozoic faults during the Alpine orogeny on the Oligocene–Miocene boundary. Rare Tlbearing Mn oxides occur in an outside zone of the encrustations, filling small fractures and voids in limestone forming the fault breccia. Tl contents, reaching 20.82wt% as Tl₂O, exceed by more than two orders of magnitude those reported in similar minerals before, making the oxides unique on a world scale. The Tl-bearing Mn oxides from Zalas reflect intensive weathering of an older Tl-bearing sulphide mineralization in an arid climate, involving saline fluids delivered to the groundwater system as the nappe structure of the Carpathians was developing during the Sava tectonic phase Oligocene/Miocene boundary.

The green colour of prasiolite, defined as naturally occurring transparent macrocrystalline α-quartz with primary colouration, results from the optical absorption centred at ~13,660 cm⁻¹ and attributed to the Fe_VI²⁺→Fe_VI³⁺ intervalence charge transfer (Platonov et al. 1992). However, optical absorption spectroscopy of blue-green to green quartz from Rakowice Wielkie, Sudetes, south-western Poland, shows that its primary colouration results from the combination of this band and absorptions at ~18,500 cm⁻¹ and ~16,250 cm⁻¹. The first is assigned to a hole centre Fe⁴⁺_s(Fe³⁺_s-e⁻) combined with an electron centre Fe²⁺_I6(Fe³⁺_I6+e⁻), while the second from AlO₄⁴⁻ defects. The quartz is blue-green if the 18,500 cm⁻¹ prevails and becomes pale green if the 16,250 cm⁻¹ band predominates. These colours seem to represent intermediate colour varieties between amethyst and prasiolite. We also suggest that spectral features of coloured quartz varieties might be useful indicators of changes in the physical- and chemical characteristics of the mineral-forming fluids.

Several types of coal waste (freshly-dumped waste, self-heated waste and waste eroded by rain water), river sediments and river water were sampled. The aim was to identify the types of phenols present on the dumps together with their relative abundances. Gas chromatography-mass spectrometry (GC-MS) analyses of a large number of samples (234) statistically underpin the phenol distributions in the sample sets. The largest average relative contents (1.17-13.3%) of phenols occur in the self-heated samples. In these, relatively high amounts of phenol, C1- and C2-phenols reflect the thermal destruction of vitrinite. In fresh coal waste, C2- and C3-phenols that originated from the bacterial/fungal degradation and oxidation of vitrinite particles are the most common (0.6 rel.%). Water-washed coal waste and water samples contain lower quantities of phenols. In the river sediments, the phenols present are the result of bacterial- or fungal decay of coaly organic matter or are of industrial origin.

We report on the occurrence of peculiar Ba- and Ti-enriched dark mica in metasedimentary rocks that underwent high-pressure metamorphism in the diamond stability field followed by decompression to granulite facies conditions. The mica occurs as well-developed preserved laths in a quartzofeldspathic matrix. The mean concentrations of BaO and TiO₂ in the mica are 11.54 and 7.80wt%, respectively. The maximum amounts of these components are 13.38wt% BaO and 8.45wt% TiO₂. The mean crystallochemical formula can be expressed as (K_0.54Ba_0.39Na_0.02Ca_0.01)_Σ0.96(Fe_1.37Mg_0.85Ti_0.50Al_0.29Mn_0.01Cr_0.01)_Σ3.03(Si_2.59Al_1.41)_Σ4.00O₁₀(OH_1.30O_0.66F_0.02S_0.01)_Σ1.99, with oxyannite, oxy-ferrokinoshitalite and siderophyllite as dominating end-members. Based on the petrographical observations, it is proposed that the dark mica was formed at a rather late stage in the evolution of the parental rock, i.e. under granulite facies conditions.