Volume 41 (2010): Issue 1-2 (January 2010)

This report presents the results of petrographical and mineralogical (optical microscopy, SEM/EDS) study of xenotime derived from the Upper (Middle?) Cambrian rocks (Wiśniówka Sandstone Fm.) of the abandoned Podwiśniówka mine pit. This is the first work on this mineral from the Holy Cross Mts. The authigenic xenotime occurs primarily as overgrowths around/on zircon in siliciclastic rocks. Moreover, this mineral is characterized by the large size of the overgrowths reaching 50 μm long and 20 μm wide. The presence of pyritecoated zircon/xenotime aggregates indicates that the xenotime formed prior to hydrothermal quartz-pyrite mineralization. The apparent lack of xenotime and vein pyrite in the tuff-bearing series, compared to the other two series displaying hydrothermal signature (pyrite, hematite, nacrite, jarosite), as well as considerable variations of the xenotime overgrowths in size and morphology, and their dominant irregular patchy-zonal microtexture may provide evidence for direct precipitation of this mineral from hydrothermal fluids.

Fine-grained aggregates of lithiophorite are associated with cryptomelane, romanèchite, birnessite and graphite in the Precambrian Eastern Ghats manganese ore deposit of Nishikhal, south Orissa, India. High-cobalt lithiophorite is reported for the first time from the manganese ores. The mode of occurrence and the chemical composition of the lithiophorite are discussed. Along with manganese and aluminium, the lithiophorite contains appreciable quantities of CoO (1.59-8.56%) together with trace amounts of Cu, Ni, Zn, Ti, Ca, Mg, Na, K and P. The Nishikhal lithiophorite is a transition metal-rich lithiophorite.

Radioactive veins in shear zones of the El-Seboah granite in Egypt with anomalous concentrations of Nd, Ce, Zr, Y, Nb, Sm, Th and U were studied by petrographic microscopy, x-ray diffraction, ⁵⁷Fe Mössbauer and wet chemical methods. The veins are composed essentially of quartz, aegirine-augite and minor K-feldspar ± α-iron oxide (hematite) ± γ-iron oxide hydroxide (goethite). They likely represent late-stage felsic melt that was quenched and devitrified at high temperature to yield crystals and crystallites, and then subjected to low temperature alteration during which most of the K feldspar transformed to kaolinite and opal. Mössbauer parameters of the samples indicate that the existing Fe-bearing minerals are primary, with appreciable ordering in the Fe sites. The bulk-sample iron (ΣFe) contents are extremely high (12.3-22.4%). The extent of oxidation of the Fe has been found to be 100% by Mössbauer spectroscopy and 95.36-99.69% by a chemical method. These conditions of Fe enrichment and strong oxidation suggest that the veins are extreme differentiates of granite magmas where high states of oxygen fugacity prevailed.

A new association of ore minerals has been found in the Lower and Middle Triassic rocks in the vicinity of the village of Woźniki in the NW part of the Upper Silesian district. In addition to the typical Zn-Pb-Fe association in dolomites, copper sulphides have been detected in the sandstones and conglomerates of the Lower Bunter. Copper mineralization occurs in the sandstone matrix and is represented by bornite, chalcopyrite, chalcocite, tetrahedrite and covellite. High admixtures of zinc in Cu sulphides and admixtures of copper in Zn-Pb sulphides suggest a common source for the metal-transporting fluids and a single period of sulphide crystallization.

An effective remediation strategy for a polluted site should take the absolute amount of the pollutant(s) into account. Here, we present an elemental budget for As, Sb and Fe in two tailing impoundments of the former Sb-Au deposit near Pezinok, Slovakia. The two impoundments contain 5,740×10³ kg As, 6,360×10³ kg Sb and 50,105×10³ kg Fe. An estimated total Au content in the impoundments is 132 kg. The most abundant minerals in the tailings are quartz, illite, and chlorite. The content of carbonates in the tailings is 3.5-10.5 wt% calcite equivalent and we estimate that the carbonates are sufficiently abundant to buffer the pH at circumneutral values, up to the point when all pyrite decomposes. The possible courses of action are i) do nothing, ii) build an active barrier to capture the released As and Sb, iii) isolate the impoundments from rain and ground water and iv) use the impoundments as a source of Sb and redeposit the waste in a safer form. The simplest approach is to do nothing, which seems to be the most likely course of events, given the current economic, political and societal state of the Slovak Republic. Although this action costs nothing in the short term, it may cause significant damage to the environment, especially to the alluvial sediments and associated water resources in the long term.

The Upper Ordovician sedimentary succession of southeast Ireland is riddled with almost synsedimentary igneous intrusions. A study was required to determine any effects of these intrusions on Kübler Index (KI) so that further sampling for a regional study could be undertaken and the results would be unbiased. Sampling was carried out on the low-grade metapelites (Southeast Ireland) around the rhyolitic and doleritic intrusions, which were intruded into the still soft sediment. Clay mineralogy was determined using X-ray diffractometry and KI values were measured; SEM and whole rock elemental analyses were applied to complement the results of the XRD work. KIs immediately around rhyolitic intrusions were observed in all cases to be lower than the regional KI, however this was not seen around doleritic intrusions. SEM work shows illite grain sizes following the KI trend and K2^O were noted to be highest where KI was lowest. Rare earth elements (REEs) show some mobilization which also follows the KI trend. This is considered to be a residual effect of hydrothermal fluids / volatiles hosted by the rhyolites but not encountered in the dolerites. Chlorite crystallinity is not affected as it most likely crystallized after the hydrothermal event. The KI is often used as a proxy for illite crystallinity in studies of low grade metamorphism but is influenced by many parameters and care should be taken when applying this technique to studies of regional metamorphism.