Peter Bacik

BACKGROUND A significant proportion of anthropogenic dust particles are present in the atmosphere. In particular, these include industrial and municipal dust, black carbon from fossil fuels and biomass. Mineralogical research of dust particles in the air is important for knowing their impact on public health in hazardous work environments (not only in Slovakia). In the recent past (in 2000-2010), research of dust fallouts from mining and processing of mineral resources was carried out. Specifically, it was focused on the Lubeník and Jelšava area, where the environment and population were adversely affected by mining activities and magnesite (MgCO3) processing treatment. METHODS The dust obtained from the plastic containers at the sampling stations was filtered in distilled-water wash. Afterwards the dust dispersion, respirable fraction and chemical composition were determined by analytical methods. The mineralogical characteristics of the particles were determined by X-ray powder di...

The Sieggraben structural complex occupies a middle position in the Austroalpine basement nappe system in the Eastern Alps. Investigated area is located at the southeastern part of Austria between the Steinbach and Gschorrholz villages (approximately 150 km south of Vienna). The aim of this paper is to characterize petrographic and mineral chemical composition of meta-harzburgites and meta-pyroxenites. Identified mineral assemblage from selected microstructures of massive to sheared meta-pyroxenite and meta-harzburgite is composed of Ol, Opx, Cpx, zoned Amp, Chl, serpentine group minerals Atg/Ctl, spinel group minerals Spl, Hc and rare Tlc. Meta-harzburgites and meta-pyroxenites are members of a subduction complex.

Faceted tourmaline gemstones obtained from commercial sources as elbaites were studied with non-destructive spectroscopic methods. We applied Raman spectroscopy for mineral identification and UV/Vis/NIR spectroscopy for de - termination of chromophores. We identified the most of samples as fluor-elbaite to elbaite by Raman spectroscopy except one sample which has likely fluor-dravitic to fluor-uvitic composition. In green elbaitic tourmalines divalent iron is the most significant chromophore. Yellow-green and pink elbaitic tourmaline are coloured by Mn in divalent and trivalent form, respectively. The green colour of dravitic to uvitic tourmaline is the result of absorption caused by V.

The Sieggraben structural complex is located in the Eastern Alps and went through complicated tectonothermal evolution. Lithotypes are represented by metabasic rocks, metacarbonates, metapelites, and serpentinites. Metabasites consist of amphiboles and eclogites. The whole unit underwent two MP/HP metamorphic stages - a D1 prograde burial stage and a D2 exhumation stage. The D1 prograde burial stage resulted in the forming of Omp with over 30 % of Jd component, Am1, Pl1. P-T conditions of the D1 stage were calculated at 610-650 °C (Grt-Cpx geothermometer) and 16-17 kbar (Grt-Cpx- Pl-Qtz geobarometer). The D2 exhumation stage resulted in the forming of Am2, Pl2, and Cpx2 mineral association. P-T conditions of the D2 stage were set to 700 °C at 12 kbar by Grt-Bt geothermometer and Grt-Pl-Ky-Qtz geothermobarometer. Previously published P-T path was recalculated using new geothermobarometry calculations.

The Sieggraben structural complex occupies a middle position (the former Middle Austroalpine Unit) in the Austroalpine basement nappe system in the Eastern Alps. It is reported as a part of the Upper Austroalpine Unit and is located in the Rosalien Mountains between the Sieggraben and Schwarzenbach villages (approximately 80 km south of Vienna). Our main goal is to precisely determine the petrography and mineral chemistry of lensoidal metaultramafic bodies in metapelites (micaschists to gneisses, migmatitic gneisses), metabasites (eclogites, amphibolites, metagabbros), impure metacarbonates to calc-silicate rocks (marbles), crosscut by veins of granitic orthogneisses (leucocrate metagranites, metapegmatites) in a pre-Alpine basement complex. Mineral assemblages from representative microstructures of massive to strongly schistose metaultramafics were studied by polarized-light microscopy and mineral chemical compositions were determined by Cameca SX-100 electron microprobe. Part of t...

This work presents the results of investigation of the primary minerals and their weathering products of two tailing ponds near the villages of Rudňany and Slovinky in eastern Slovakia. The tailings are near-neutral or slightly alkaline (pH = 7.2–8.8) because the acidity generated by the decomposition of the sulfides is efficiently neutralized by the abundant carbonate minerals. The most frequent primary gangue minerals are siderite, quartz, barite, and muscovite. The prevailing primary sulfide minerals in both tailing ponds are pyrite and chalcopyrite; less common are tetrahedrite and arsenopyrite. The most frequent secondary and tertiary ( i.e. , formed in the tailings, not in the oxidation zone of the deposits) minerals at both localities are iron oxides, either goethite or poorly crystalline hydrous ferric oxide. Other minerals (cuprite, malachite, delafossite; identified by X-ray microdiffraction or Raman spectroscopy) are minor or rare and occur only in Slovinky. The iron oxide minerals are enriched in a suite of elements, including Cu, Si, Ca, Zn, As, Mg, and Mn. The transformations of the poorly crystalline hydrous ferric oxide to goethite and maturation of goethite is controlled by both high-valence tetrahedral cations (Si, As, P) and lower-valence octahedral cations (Cu), as shown by the measurements of the size of coherently diffracting domains in goethite and the chemical composition of goethite. The iron oxide minerals, by virtue of their adsorption capacity, prevent separate minerals of many metals and metalloids (Cu, Ca, As, Sb) from nucleating and growing, and therefore control the entire neutral mine drainage (NMD) system. Geochemical modeling of the discharged waters shows that all common Cu and ferric arsenate minerals are strongly undersaturated, confirming the central role of iron oxide phases in the NMD system.

ABSTRACT This contribution reviews and affords new insights into the crystal chemistry of gadolinite-datolite group (GDG) silicates by re-examination of published and unpublished analytical data. More than 200 electron microprobe analyses (EMPA) and data from both single-crystal and powder X-ray diffraction of 53 samples of GDG silicates were collected to study site occupancy effects on local and long-distance geometry of the crystal structure. Results were achieved by statistical analysis and bond-length and bond-angle calculations. Here, crystal-structure geometry and site occupancy dependence is manifested in the GDG chemical composition and lattice parameters. While the substitution of B for Be at the tetrahedral Z site has the greatest impact on the size of the a parameter, variations in W-site occupancy result in a change in the size of the b parameter. Moreover, the degree of variability in the occupancy of the W site appears to influence the layer-stacking order, which differs between well ordered datolite and weakly ordered gadolinite-subgroup (GSG) minerals. This is documented by c parameter variability. The relationship between the X-site occupancy and lattice parameters is explained by the Jahn-Teller effect, which induces bond-length and angular distortion of the XO6 octahedron. In addition, the structural arrangement of the X site excludes large cation (such as Ca, Bi, and REE) occupancy without any significant impact on the size of the XO6 octahedron. Consequently, the formula for minasgeraisite-(Y) with the originally proposed Ca occupancy of the X site is questionable, since no significant difference from hingganite lattice parameters was observed. Thus the mineral requires further structural refinement. The structural arrangement of GDG silicates suggests that two dominant substitution vectors control their chemical composition: CaB(REE)−1Be−1 and Fe2+O2(OH)−2. However, both substitutions are more widespread in GSG minerals than in datolite subgroup (DSG) minerals. This may result from different geochemical properties of their genetic environment. However, there can be structural factors concerning X, W, and Z site occupancy which differentiate the far more chemically variable GSG from DSG.

The paper deals with sodium sulphate crystallization in pore spaces of Thassos marble and presents the 3D visualization of intergranular fractures causing a deterioration of the specimen by the salt crystallization. Cylindrical marble specimen with diameter 20 mm and length 50 mm has been submitted to 15 cycles of the dipping in 14 % solution of mirabilite (Na2SO4·10 H2O) according to the STN EN 12370 standard methodical test. Using electron methods (polarization microscopy, SEM – Scanning electron microscopy, XRD – X-ray diff raction, EMPA – Electron-microprobe analysis) and by monitoring of selected physical parameters (changes in weight and changes in P-waves velocities), in fi rst the mineral composition and microstructure of the marble have been characterized and consequently the eff ects induced by cyclic activity of sodium sulphate with the marble have been analysed. Mercury intrusion porosimetry (MIP) method has been used for specifi cation of the porosity and detail pore st...

The examined sample of Ca-skarn (calc-silicate rock) from the locality Dolinkovský Hill of Modra-Harmónia is geologically incorporated into Pezinok group crystalline basement of Malé Karpaty Mts. It represents a contact metamorphism product of granite intrusion Modra massif. 3D distribution of titanite inclusions was studied in 6 mm garnet porphyroblast. X-ray microtomography method and other supporting identification methods (polarized light microscopy, scanning electron microscopy, electron microprobe analysis and microRaman spectroscopy) were used for 3D visualization and volume distribution of titanite inclusions in garnet. Garnet grain has typical rhombic dodecahedron crystal shape. In terms of composition it’s dominantly represented by grossular component with a lower share of andradite component. Faint chemical zoning is reflected by the increase in the share of andradite component at the expense of grossular component. Slightly variable chemical composition of titanite is af...

A pavement brick taken from a Romanesque part of the church in Pác, in the Trnava County, Slovakia, was investigated by x-ray diffraction analysis (XRD) and thermal analyses as differential thermal analysis (DTA), thermogravimetry (TG) and thermodilatometry (TD). It was found that the brick contained dehydroxylated illitic clay, calcite and quartz. As revealed, dehydroxylation was completely finished and no redehydroxylation was observed. Partial decomposition of calcite was also found. The estimated firing temperature is between 600 °C and 700 °C.

ABSTRACT We report pyrrhotite, anhydrite and dolomite crystal rods in fluorapatite occurring in silicate-bearing carbonate rocks associated with UHP eclogites in the Tromsø Nappe of the Scandinavian Caledonides in Norway. The apatite-rich rock (up to 10 vol. %) is composed of Mg-rich calcite-dolomite exsolutions, almandine-grossular garnet, low-jadeite clinopyroxene, magnesiohornblende, phlogopite, and accessory minerals represented mainly by zircon, Fe-Ti oxides and allanite. Fluorapatite occurring as euhedral crystals in the carbonate matrix and as inclusions in garnet and clinopyroxene shows up to 45 mol. % of the hydroxylapatite component, traces of CO32–, probably CN and small amounts of the britholite and ellestadite components. Pyrrhotite occurs as crystallographically oriented rods parallel to the c axis of the host hydroxyl-bearing fluorapatite either as a dense trellis or in the form of scarce inclusions. Precipitation of pyrrhotite in the fluorapatite was probably facilitated by a volatile sulphur phase (e.g., H2S), which was enclosed within the apatite nano-channels and interacted with Fe in apatite. Anhydrite and dolomite rods have also been identified in the apatite, pointing to the presence of HCO3 in the fluids. The anhydrite is also trapped by exsolved dolomite from calcite in the carbonate matrix. Crystallisation of anhydrite, and probably also the associated pyrrhotite, at about 550–650 °C was deduced from calcite–dolomite thermometry. At these amphibolite-facies, post-UHP conditions rapid pyrrhotite precipitation in the host apatite is presumed. Relaxation of the fluorapatite structure in the a-axis direction during decompression facilitated the formation of the oriented inclusions in apatite.

Conference title - 9. Vyrocny predvianocny seminar Slovenskej geologickej spolocnosti--9th Annual seminar of the Slovak Geological Society, Copyright - GeoRef in Process, Copyright 2013, American Geosciences Institute. After editing and indexing, this record will be added to Georef., Language of summary - Undetermined, Pages - 488, ProQuest ID - 885335969, SubjectsTermNotLitGenreText - alteration; aluminum; andesites; argillization; Biely Vrch Mountain; Central Europe; chemical composition; chlorine; correlation coefficient; crystal chemistry; Europe; halogens; hydrothermal alteration; igneous rocks; Javorie Mountain; metals; metasomatism; propylitization; ring silicates; silicates; Slovakia; statistical analysis; tourmaline group; volcanic rocks, Last updated - 2012-12-13, CODEN - MSLOBI, Corporate institution author - Bacik, P; Ozdin, D; Uher, P; Kodera, P; Nemeth, Zoltan; Plasienka, Dusan; Simon, Ladislav; Kohut, Milan; Iglarova, Lubica; Moravcova, Martina, DOI - 600528-4; 0369-2...

ABSTRACT Optical and crystal-chemical changes in two beryl varieties after the heat treatment were determined using a wide spectrum of analytical methods. Studied aquamarines are generally more enriched in Fe (up to 0.25 apfu) and alkali (up to 0.08 apfu) than yellow beryls (up to 0.07 apfu Fe, up to 0.04 apfu alkali). The determined c/a ratio of 0.997-0.998 classified all our studied beryls as “normal” beryls. While no crystal structure changes were observed in samples heated to 700°C, those heated to 900 and 1100°C exhibited cracks and fissures. Reduced Fe occurred in samples heated between 300 and 700°C and subsequent oxidation from 900 to 1100°C induced changes in their colour and clarity. The Fe-bearing beryl colour is controlled by the position of the absorption edge and the presence of a broad band attributed to Fe2+ in the NIR region. Blue colour results from the absorption edge located deeper in the UV region and the presence of broad band in the NIR region. Shift of absorption edge to the visible region at the presence of the broad band gives a yellow colour. Although our studied beryls are enriched in H2O I molecule due to their low alkali content, the H2O II molecule is also present. The following two dehydration processes were observed; (1) release of one double-coordinating H2O II molecule at 300-500°C, and (2) total dehydration at 900-1100°C. The observed cracks and fissures likely resulted from channel water release in large beryl crystals.

ABSTRACT The initial to advanced stage of monazite breakdown was identified in a granitic orthogneiss from the pre- Alpine basement in the Veľký Zelený Potok Valley (the Veporic Unit, Western Carpathians, central Slovakia). Monazite-(Ce) formed during Variscan metamorphism of the original Cambrian to Ordovician granitic rock. Two younger, Permian post-magmatic hydrothermal, and Cretaceous metamorphic-hydrothermal events caused a breakdown of the monazite to secondary egg-shaped coronal structures (100 to 500 μmin diameter) with concentric newly-formed mineral phases. Two principal breakdown stages and newly formed mineral assemblages are recognizable: (1) partial to complete replacement of primary monazitewith an internal apatite+ThSiO4 (huttonite or thorite) zone and an external allanite-(Ce) to clinozoisite zone; (2) hydroxylbastnäsite-(Ce) partly replacing apatite+ThSiO4 and allanite to clinozoisite aggregates. The monazite breakdown was initiated by fluid sources differing in composition. Stage (1) originated due to post-magmatic hydrothermal fluids, whereas stage (2) indicates an input of younger, CO2-bearing metamorphic-hydrothermal fluids.

The pre-Caledonian NYF Skoddefjellet pegmatite in Wedel Jarlsberg Land, Svalbard, contains xenotime-(Y) that is partly replaced by fluorapatite-hingganite-(Y) reaction coronas. Hingganite-(Y) contains up to 2.0 wt.% of Gd2O3, 4.7 wt.% of Dy2O3, 3.3 wt.% of Er2O3 and 5.5 wt.% of Yb2O3. Such unusual, previously undescribed, xenotime-(Y) breakdown was caused by Ca- and F-bearing fluids interacting with the pegmatite. The occurrence of hinnganite-(Y) as a breakdown product of xenotime-(Y) implies that a Be-bearing phase (beryl in this case) was also involved in the reaction. There are few Ca-bearing primary phases in the pegmatite, indicating that the source of fluid was probably located in the generally Ca-richer host rocks (metasediments), though the fluid composition was modified during metasomatism of the pegmatite (i.e. beryl dissolution).

ABSTRACT Baroque bricks were investigated by DTA, TG, EGA, TDA, and XRD. The analyses showed that the brick consisted of dehydroxylated illite, quartz, and calcite. Dehydroxylation as a consequence of the former rehydroxylation was not found probably because of protection of the bricks by plaster. Between the temperatures 600 and 800 °C, (a) intensive mass loss in TG, (b) endothermic minimum in DTA, (c) intensive escape of CO2 in EGA, and (d) contraction of the sample in TDA were observed. All these events belong to decomposition of calcite. As follows from these results, the maximum firing temperature was about 700 °C. The bricks have relatively high porosity ~43 % and specific surface area ~18.6 m2 g−1.

Oxy-schorl (IMA 2011-011), ideally Na(Fe2+2Al)Al6Si6O18(BO3)3(OH)3O, a new mineral species of the tourmaline supergroup, is described. In Zlatá Idka, Slovak Republic (type locality), fan-shaped aggregates of greenish black acicular crystals ranging up to 2 cm in size, forming aggregates up to 3.5 cm thick were found in extensively metasomatically altered metarhyolite pyroclastics with Qtz+Ab+Ms. In Přibyslavice, Czech Republic (co-type locality), abundant brownish black subhedral, columnar crystals of oxy-schorl, up to 1 cm in size, arranged in thin layers, or irregular clusters up to 5 cm in diameter, occur in a foliated muscovite-tourmaline orthogneiss associated with Kfs+Ab+Qtz+Ms+Bt+Grt. Oxy-schorl from both localities has a Mohs hardness of 7 with no observable cleavage and parting. The measured and calculated densities are 3.17(2) and 3.208 g/cm3 (Zlatá Idka) and 3.19(1) and 3.198 g/cm3 (Přibyslavice), respectively. In plane-polarized light, oxy-schorl is pleochroic; O = green to bluish-green, E = pale yellowish to nearly colorless (Zlatá Idka) and O = dark grayish-green, E = pale brown (Přibyslavice), uniaxial negative, ω = 1.663(2), ɛ = 1.641(2) (Zlatá Idka) and ω = 1.662(2), ɛ = 1.637(2) (Přibyslavice). Oxy-schorl is trigonal, space group R3m, Z = 3, a = 15.916(3) Å, c = 7.107(1) Å, V = 1559.1(4) Å3 (Zlatá Idka) and a = 15.985(1) Å, c = 7.154(1) Å, V = 1583.1(2) Å3 (Přibyslavice). The composition (average of 5 electron microprobe analyses from Zlatá Idka and 5 from Přibyslavice) is (in wt%): SiO2 33.85 (34.57), TiO2 <0.05 (0.72), Al2O3 39.08 (33.55), Fe2O3 not determined (0.61), FeO 11.59 (13.07), MnO <0.06 (0.10), MgO 0.04 (0.74), CaO 0.30 (0.09), Na2O 1.67 (1.76), K2O <0.02 (0.03), F 0.26 (0.56), Cl 0.01 (<0.01), B2O3 (calc.) 10.39 (10.11), H2O (from the crystal-structure refinement) 2.92 (2.72), sum 99.29 (98.41) for Zlatá Idka and Přibyslavice (in parentheses). A combination of EMPA, Mössbauer spectroscopy, and crystal-structure refinement yields empirical formulas (Na0.591Ca0.103□0.306)∑1.000(Al1.885Fe2+1.108Mn0.005Ti0.002)∑3.000(Al5.428Mg0.572)∑6.000(Si5.506Al0.494)∑6.000O18 (BO3)3(OH)3(O0.625OH0236F0.136Cl0.003)∑1000 for Zlatá Idka, and (Na0.586Ca0.017K0.006□0.391)∑1.000(Fe2+1.879Mn0.015 Al1.013Ti0.093)∑3.00(Al5.732Mg0.190Fe3+0.078)∑6.000(Si5.944Al0.056)∑6.000O18(BO3)3(OH)3(O0.579F0.307OH0.115)∑1.000 for Přibyslavice. Oxy-schorl is derived from schorl end-member by the AlOFe–1(OH)–1 substitution. The studied crystals of oxy-schorl represent two distinct ordering mechanisms: disorder of R2+ and R3+ cations in octahedral sites and all O ordered in the W site (Zlatá Idka), and R2+ and R3+ cations ordered in the Y and Z sites and O disordered in the V and W sites (Přibyslavice).

Green to grayish green tourmaline crystals (up to 10 cm across), with distinct optical zoning, occurs with quartz, blocky albite and muscovite in the Forshammar granitic pegmatite, central Bergslagen province, Sweden. Tourmaline contains inclusions of zircon and xenotime-(Y), and it is cut by veinlets of muscovite and hydroxylbastnäsite-(Ce). Microanalytical and structural data (from the rim) indicate that the tourmaline can be classified as a dravite with moderate Al–Mg disorder at the Y and Z sites. Tourmaline displays chemical zoning that reflects the distribution of Fe, Mg, Al, Ca and Na. The Mg/(Mg+Fe) value is high; it decreases from core (∼0.85) to intermediate zone (0.76–0.79), but increases in the rim and vein dravite (0.93). The core has the highest proportion of X-site vacancy and Al content, whereas the intermediate zone is the most enriched in Fe and Na. The rim is slightly depleted in Al and has the highest Na compared to inner zones. Tourmaline veins crosscut the pre-existing tourmaline and are relatively more enriched in Na and Ca. The main compositional variations are driven by AlX□Mg−1Na−1 and AlOMg−1(OH)−1 substitutions. The Forshammar dravite shows the highest known concentrations of REE from pegmatite tourmaline, ≤1200 ppm REE, ≤210 ppm La, ≤670 ppm Ce; the chondrite-normalized patterns reveal high LaN/YbN (32 to 464) values and strongly negative Eu anomalies (Eu/Eu* = 0.005 to 0.05). The contents of Ti, Mn, Y and REE generally increase at the boundary of the intermediate zone and rim, whereas the contents of Zn, Ga and Sn decrease from the core to the rim. The core is likely a product of an early magmatic process during the late Svecofennian pegmatite formation (∼1.8 Ga) as suggested by oscillatory zoning of trace elements. The intermediate zone, rim and tourmaline veins originated during the late magmatic to hydrothermal stage. Hydroxylbastnäsite-(Ce) and muscovite are apparently the final products of the hydrothermal process.

Radial aggregates of blue-grey tourmaline were found in plagioclase-muscovite-scapolite metaevaporite layers in dolomite marble near Prosetín (Olešnice Unit, Moravicum, Czech Republic). It occurs in association with plagioclase (An15-37), muscovite, scapolite, phlogopite, vermiculite, pumpellyite-(Al), and clinozoisite. Electron-microprobe analyses of tourmaline show dravitic composition with very high content of Mg (1.92 to 2.77 apfu), Al (up to 6.71 apfu), low content of Fe (up to 0.39 apfu) and variable amounts of vacancies (0.09 to 0.47) and Ca (0.03 to 0.29 apfu) in the X-site. Some analyses correspond to “oxy-dravite” and some others almost attain magnesio-foitite compositions. The proportion of X-site vacancy decreases from the crystal cores to their rims while Ca content increases. Generally, charge excess due to the high Al-contents is balanced either by an increasing X-site vacancy or by deprotonization of WOH; the WO2- content calculated from charge-balanced formula attains 0.71 apfu. Lattice parameters [a = 15.9116(6) Å; c = 7.1987(4) Å] and calculated average bond lengths ( = 1.995 Å;  = 1.929 Å) indicate a relatively high Al-Mg disorder. Three main substitution mechanisms are inferred to operate in the studied magnesian tourmalines: (1) CaMg(NaAl)-1, mainly in Ca-enriched dravite, (2) X  Al(NaMg)-1 in nearly magnesio-foititic compositions, and (3) AlO(MgOH)-1 in “oxy-dravitic” members. The tourmaline is relatively poor in trace elements; only Ti, Sr, and Ga exceed 100 ppm according to LA-ICP-MS study. There is a pronounced positive correlation between Sr and Ca (r2 = 0.77), which suggests that Sr accumulated in Ca-enriched zones of dravite. The pale blue-grey color of the studied tourmalines is most likely a result of Fe2+ crystal field transitions along with the absence of significant amounts of other chromophores. Trace-element contents, mineral assemblage and compositional zoning of tourmalines as well as host-rock mineral association suggest prograde metamorphic growth and support metaevaporitic origin of the plagioclase-muscovite-scapolite rocks.

A pavement brick taken from a Romanesque part of the church in Pác, in the Trnava County, Slovakia, was investigated by x-ray diffraction analysis (XRD) and thermal analyses as differential thermal analysis (DTA), thermogravimetry (TG) and thermodilatometry (TD). It was found that the brick contained dehydroxylated illitic clay, calcite and quartz. As revealed, dehydroxylation was completely finished and no redehydroxylation was observed. Partial decomposition of calcite was also found. The estimated firing temperature is between 600 °C and 700 °C.

The initial to advanced stage of monazite breakdown was identified in a granitic orthogneiss from the pre-Alpine basement in the Veľký Zelený Potok Valley (the Veporic Unit, Western Carpathians, central Slovakia). Monazite-(Ce) formed during Variscan metamorphism of the original Cambrian to Ordovician granitic rock. Two younger, Permian post-magmatic hydrothermal, and Cretaceous metamorphic-hydrothermal events caused a breakdown of the monazite to secondary egg-shaped coronal structures (100 to 500 μm in diameter) with concentric newly-formed mineral phases. Two principal breakdown stages and newly formed mineral assemblages are recognizable: (1) partial to complete replacement of primary monazite with an internal apatite + ThSiO4 (huttonite or thorite) zone and an external allanite-(Ce) to clinozoisite zone; (2) hydroxylbastnäsite-(Ce) partly replacing apatite + ThSiO4 and allanite to clinozoisite aggregates. The monazite breakdown was initiated by fluid sources differing in composition. Stage (1) originated due to post-magmatic hydrothermal fluids, whereas stage (2) indicates an input of younger, CO2-bearing metamorphic-hydrothermal fluids.

Green ceramic material is a mixture of 60 wt % of clay, 10 wt % of calcite waste and 30 wt % of the clay fired at 1000°C for 90 min. The clay consists of 83 wt % of phyllosicates. The samples were undergone to XRD analysis, DTA, TGA, TDA and mf-TMA during heating 5°C/min. The mf-TMA was based on the measuring Young’s modulus by resonant method. The samples pass over several changes–release of the physically bounded water, burning of the organic impurities, dehydroxylation of kaolinite and illite, decomposition of calcite and creation of anorthite and mullite. The first visible increasing of Young’s modulus, which runs from room temperature to ~300°C, is a consequence of the release of the physically bounded water from pores, micropores and faces of crystals. In a temperature interval 450–650°C dehydroxylation of kaolinite and illite takes place, then decomposition of calcite runs between ~700 and 900°C. These three processes produce new structures which are mechanically weak because of significant part of micropores. In spite of that, Young’s modulus tends to slightly increase from 500 to 750°C and decreases only in a small extent during heating from 750 to 850°C. Then a steep increase of Young’s modulus values is recorded which can be ascribed to superposition of the solid-state sintering and creation of anortite at ~950°C and mullite above 950°C.

Heat treatment was performed on selected Fe-dominant tourmalines to establish the nature of any change in optical properties. Two tourmaline samples from Dolní Bory, Czech Republic (TDB) and Vlachovo, Slovakia (TVL) were heated at 450, 700 and 900°C at 0.1 mPa and ambient oxidation conditions for 8 h. EMPA study shows that tourmaline from Vlachovo has schorlitic composition and tourmaline from Dolní Bory is alkali-depleted schorl to foitite. Although the black colour remained unchanged after heating at 450°C, it changed to brown at 700°C and reddish brown at 900°C. No significant changes of chemical composition were observed during heating. X-ray diffraction, infrared and Mössbauer study showed negligible oxidation of tourmaline heated at 450°C, but a significant change in iron valency state and deprotonization at 700°C. The oxidation of Fe is the main cause of tourmaline colour change, and the substitution vector for oxidation of Fe is Fe3+OFe −1 2+(OH)−1. The
predicted deprotonization of OH was confirmed by infrared spectroscopy, which documented a decrease in OH groups in both samples, mainly at the V site. The oxidation of Fe is mostly significant in the Y site as documented on the compression of the Y-site octahedra and subsequent decrease in the a lattice parameter. This feature is consistent with lattice dimensions in the transition from schorl and foitite dimensions to those consistent with fluor-buergerite. The Z-site octahedra did not compressed and were not affected by heating-induced Fe oxidation, which indicates only negligible content of Z Fe2+ in original samples. After heating at 900°C, the tourmaline structure collapsed likely due to the thermally induced weakening of bonds in Y and Z octahedra, which results in amorphization of tourmaline. Subsequently, breakdown products including Fe-oxides and mullite replaced alkali-depleted amorphized tourmaline.

Supergene mineralization at the hydrothermal Farbište ore occurrence near Poniky, central Slovakia, was studied using optical and electron scanning microscopy, X-ray powder diffraction, electron microprobe and IR spectroscopy. Two principal associations of the supergene minerals were observed. The first is represented mostly by tyrolite with a higher content of sulphate groups and chrysocolla associated with copper carbonates. The second is characterized by a rich assemblage of copper arsenates: low-S tyrolite, strashimirite, parnauite, olivenite, cornwallite, cornubite, euchroite and clinoclase, which occur together with chrysocolla, bariopharmacosiderite-Q, brochantite, azurite and malachite. Both associations formed as a result of decomposition of primary ore minerals, especially tennantite, which is the prevalent primary ore mineral at the Farbište occurrence and was the main source of Cu, As and S ions in the supergene zone.

Vanadium-bearing tourmaline was found in Paleozoic metacherts near Chvojnica in the Strážovské vrchy Mountains, Slovakia. The geochemistry of metacherts suggests that the protolith was deposited under anoxic conditions. Tourmaline from Chvojnica displays strong chemical zoning, with high Mg and a very low Fe content. The core has the composition of magnesio-foitite with a low V content, and is mainly controlled by alkali-deficient substitution [X□(Al,V)(NaMg)−1]. The other zones have a dravitic composition considering ordering of all Mg to the Y sites, but they may reach the composition of olenite if one proposes strong Al–Mg disorder (not proven by structural refinement). The intermediate zone is mostly enriched in V (up to 3.3 wt.% V2O3, 0.42 apfu V), and V is considered to be incorporated into the structure by VAl−1 substitution. Two rim zones were observed. Rim 1 is depleted in V but is enriched in Al. Rim 2 is similar in composition to the intermediate zone, with increased V. The increased content of trivalent cations, including Al, V and Cr in comparison to divalent Mg and Fe, suggests a deprotonation of (OH)− by the proton-deficient substitution Y(Al,V)OYMg−1(OH)−1. The increase of Ca, Ti and Mg content from core to rim may be the result of several substitutions, including TiMg(Al,V)−2, CaMgOX□−1(Al,V)−1(OH)−1. The increase of Ca, Ti and Mg content from core to rim may be the result of several substitutions, including TiMg(Al,V)−2, CaMgOX□−1(Al,V)−1(OH)−1. The V-bearing tourmaline from Chvojnica is the result of multistage Pre-Alpine regional metamorphism. The core of the grains is a product of the lower-grade M1 metamorphic event, whereas the intermediate zone corresponds to the second metamorphic event, M2. Medium-grade metamorphism (580 < T < 600°C) remobilized V from the organic matter present in the protolith of the metacherts. Rim 1 may be the result of reheating of the host rock due to the intrusion of the Malá Magura granitic massif (M3 event). The chemical composition of rim 2 was most likely influenced by the remobilization of V from older V-bearing silicates during the M3 (M3b stage?) metamorphic event.

Mechanical behavior of the heatproof stove tile ceramic material Letovice, which consists of kaolinitic clays and quartz, and small amount of mica, calcite and feldspar, was studied using the non-destructive sonic resonant method mf-TMA. To find actual dimensions and the volume mass of the sample, thermodilatometry and thermogravimetry were carried out in the same temperature regime (20–1100°C, 5°C/min) as mf-TMA. It was found that liberation of the physically bounded water from the green mass makes Young’s modulus higher. Dehydroxylation of phyllosilicates and the α → β transformation of quartz affect Young’s modulus to a lesser degree. The collapse of phyllosilicates structure above 900°C and the creation of mullite cause an increase in Young’s modulus.

The pre-Caledonian NYF Skoddefjellet pegmatite in Wedel Jarlsberg Land, Svalbard, contains xenotime-(Y) that is partly replaced by fluorapatite-hingganite-(Y) reaction coronas. Hingganite-(Y) contains up to 2.0 wt.% of Gd2O3, 4.7 wt.% of Dy2O3, 3.3 wt.% of Er2O3 and 5.5 wt.% of Yb2O3. Such unusual, previously undescribed, xenotime-(Y) breakdown was caused by Ca- and F-bearing fluids interacting with the pegmatite. The occurrence of hinnganite-(Y) as a breakdown product of xenotime-(Y) implies that a Be-bearing phase (beryl in this case) was also involved in the reaction. There are few Ca-bearing primary phases in the pegmatite, indicating that the source of fluid was probably located in the generally Ca-richer host rocks (metasediments), though the fluid composition was modified during metasomatism of the pegmatite (i.e. beryl dissolution).

Epidote-group minerals (EGM), including some of unusual chemical compositions, occur with pyrite and pyrrhotite in the Lower Paleozoic carbonaceous amphibole schist of the meta-ophiolitic Pernek Group at Rybníček, near Pezinok, southwestern Slovakia. Euhedral to anhedral dissakisite-(La), mukhinite, and clinozoisite are associated with V- and Cr-rich garnet (goldmanite – grossular – uvarovite solid-solution), V- and Cr-rich muscovite, amphibole-group minerals (magnesiohornblende, tremolite, actinolite, and edenite), diopside, titanite, albite, quartz, siderite and sulfide minerals (pyrite, pyrrhotite, rarely chalcopyrite and sphalerite). Strong compositional zoning and three stages of EGM formation were found. The core of EGM grains consists of V- and Cr-rich dissakissite-(La) (V ≤ 0.33 apfu, Cr ≤ 0.44 apfu); it grades into REE-rich mukhinite of varying Cr contents (REE ≤ 0.46 apfu, 0.13 to 0.43 apfu Cr). Clinozoisite I, which is V- and Cr-rich (V ≤ 0.40 apfu, Cr ≤ 0.42 apfu), occurs as an overgrowth upon the dissakisite–mukhinite cores. A second generation of V-, Cr- and REE-poor clinozoisite (clinozoisite II) has replaced mukhinite and clinozoisite I at the grain rim, and it is also found in veins that cut the grains. Many substitutions can change the compositions of the EGM: V3+ and Al3+ cause the VAl−1 substitution; CrAl−1 and CrV−1 substitutions may be extensive, but both are of limited extent, and Cr3+ is partly independent of the contents of substituents; Mg2+ substitution reflects the REEMgCa−1Al−1, REEMgCa−1V−1, and REEMgCa−1Cr−1 exchange-vectors. Most REE patterns show enrichment in the light REE. Chondrite-normalized REE patterns show a negative Ce anomaly and a slightly positive Eu anomaly in clinozoisite I and dissakisite-(La), but mukhinite lacks this Eu anomaly. Dissakisite-(La) most likely originated at or near the peak conditions of contact thermal metamorphism induced by the Hercynian-age intrusion of the Modra granitic massif, whereas mukhinite and clinozoisite I formed during retrogression. Clinozoisite II may reflect the younger (Alpine?) low-grade metamorphic overprint.

Accessory REE minerals occur in a small metamorphic magnetite ore deposit at Bacúch, Veporic Superunit, central Slovakia. We distinguish two populations of monazite. Monazite I forms subhedral to euhedral crystals associated with magnetite. It contains ≤12 wt.% ThO2, ≤2.7% UO2, ≤0.85% SO3, with low Ca and Sr contents. Compared to the common monazite-(Ce) I, monazite-(Nd) I (≤26.1% Nd2O3) occasionally occurs with an atomic ratio Nd:Ce up to 1.17. Monazite II is present as irregular aggregates with hingganite in younger hydrothermal quartz – albite – chlorite veinlets, or as rim zones on monazite I. Monazite II is depleted in Th and U and has an unusually high content of S (≤11.3% SO3, 0.31 apfu S) and Sr (≤8.7% SrO, 0.18 apfu Sr). This composition indicates a (Ca,Sr)S(REE,Y)−1P−1 substitution as a dominant mechanism of Sr and S entry into the monazite structure. Some monazite II crystals display an elevated Eu content (≤1.2% Eu2O3). Xenotime-(Y) forms subhedral crystals, in association with monazite-(Ce) I, magnetite, pyrite transformed to goethite (?) and quartz. Gadolinite-group minerals at Bacúch are represented by hingganite with an atomic value of X□/X(□ + Fe) in the range 0.51–0.72. Neodymium is locally the most abundant REE (17.8–18.7% Nd, ~0.56 apfu), and an Nd-dominant member of the gadolinite group was identified. The composition of hingganite-(Y) was also determined. The principal mechanism of substitution in hingganite is Fe2+O2□−1(OH)−2. Primary monazite I and xenotime are most likely products of regional metamorphism, together with magnetite mineralization. On the contrary, Sr- and S-rich monazite II and hingganite originated during a younger (Alpine) metamorphic-hydrothermal overprint in a fluid-rich regime.