Abstract The effects of ultrasonic milling, dry and wet ball milling, and vibro‐milling on the particulate properties, crystalline characteristics, morphology, and surface area of clinoptilolite (Cpt) have been investigated. Laser beam scattering technique, X‐ray diffraction (XRD), scanning electron microscopy (SEM), and nitrogen adsorption/desorption at 77 K are used to characterize the initial and ground Cpt powders. Results show that Cpt particle size is significantly reduced by all carried out milling methods in which vibro‐milling could produce particles with diameter less than 100 nm. The size distribution of Cpt is remarkably narrowed by using vibro‐ and wet ball milling. The crystallinity of Cpt noticeably decreases for the samples obtained by ball milling while vibro‐ and ultrasonic millings show a negligible effect on crystallinity. The specific surface area of Cpt is enhanced by all four milling methods.
Massive quartz-chakedony +/- opal nodules (plasma in gemology) represent a specific silica variety, which occurs in the laterite-like residues of pre-Miocene paleo-weathering of ultramafites in western Moravia (Moldanubian Zone, Bohemian Massit). These zonal silica nodules (ZSN) tend to have concentric texture with a dark green to green-brown core, pale green margin and a narrow white rim (outer surface zone). The most typical microscopic feature of ZSN is vermiform microstructure particularly in the two outer zones. Individual mines consist of micro- to non-crystalline SiO2 polymorphs with variable contents of H2O (quartz, chalcedony, moganite, opal-C/CT and opal-A). The predominant green colour is due to submicroscopic smectite pigment, while the brownish colour originated from decomposition of smectite to iron oxohydroxides. ZSN formed in subaerial, partially reducing conditions in the lower part of weathering crusts covering serpentinites. The whole process was preceded by component exchange (chloritization) along serpentinite -felsic rocks (granulite. migmatite, pegmatite veins) boundaries. The gradual silica migration and subsequent redistribution associated with the removal of aluminium, magnesium and iron led up to the formation of a zonal nodular texture dominated by SiO2 polymorphs. Newly formed minerals in micro-cavities and cracks of ZSN are represented by accessory pyrite and sporadic barite. Zonal silica nodules-bearing residues on serpentinites occur only in a narrow area which was originally covered by clay-sandy Miocene sediments of the Carpathian Foredeep in western Moravia. Probably late low-temperature fluid interaction between silicified serpentinite residuum (chlorite montmorillonite saprolite) and marine sediments may be the main factor controlling formation of ZSN.
Publikace shrnuje výsledky studia sloupeckovitých krystalů z granodioritů typu Kralovo Pole (brněnský masiv) se zaměřenim na chemickou charakteristiku, mineralni inkluze a alterace. Produktem alterace krystalů biotitu je strukturniho hlediska vermikulit, na zakladě chemismu jde o 2 typy produktů s sirokou variabilitou chemickeho složeni. Magmatogenni mineralni inkluze v krystalech vermikulitizovaneho biotitu tvoři apatit, ilmenit, magnetit, K-živec a oligoklas (plagioklas I).
Horní Halže – Mýtinka is a mineral occurrence located near Mýtinka in the Krušné hory Mts. In the past, the area was intensively mined for iron (namely hematite in quartz veins). Quartz veins are located on complicated intersections of fault systems in mica schists and migmatites (Urban – Crkal 2021). Recently, Sejkora et al. (2021) described rich Cu mineralization found in the remains of old mine dumps. Sulfide mineralization is represented by pyrite, djurleite, roxbyite, anilite, spionkopite, bornite and covellite, supergene phases by malachite, brochantite, liebethenite and pseudomalachite. The studied material (thin blue coating on a part of a single sulfide grain 3 mm in size; Fig. 1) was found by the first author in 2021 at the old mine dump and matches the material described by Sejkora et al. (2021). The blue phase was identified as langite [Cu4(SO4)(OH)6 · 2H2O] using combination of EDS, Raman and pXRD. Chemical composition of examined mineral coating was analyzed using EDS, which detected presence of Cu, S and O contents only (with Cu significantly higher than S). Raman spectrum of langite from Mýtinka (Fig. 2, Tab. 1) was acquired using a HORIBA LabRam spectrometer and the data were processed using Systat PeakFit software. Proposed spectrum model is in very good agreement with empirical data (r2 = 0.992). Assignment of individual bands according to Martens et al. (2002, 2003) is proposed in Table 1. Raman spectrum of langite is similar to those of posnjakite [Cu4(SO4)(OH)6 · H2O] and wroewolfeite [Cu4(SO4)(OH)6 · H2O]. By combining (poorly and only partially presented) data of Frost et al. (2004) and Martens et al. (2002), following differences among these phases were identified. Bands at 155 and 258 (262 in this work) cm–1 are present in the Raman spectrum of langite but missing in that of posnjakite. The Raman spectrum of wroewolfeite is devoid of bands at 507 and 596 (500 and 598 in this work) cm–1, characteristic of langite, and at 511 and 596 cm–1, characteristic of posnjakite. About 15 fragments of the coating, 20–100 µm in size, were analyzed on Panalytical X’Pert powder XRD diffractometer. Only four diffraction maxima were obtained due to a very small amount of material available. Nevertheless, corresponding d-values are in a good agreement with data for langite (Tab. 2; Galy et al. 1984).
The use of limestone in lime and clinker production respectively represents one of the biggest industrial branches worldwide. Decarbonization is a crucial part of the burning process. No clear prediction method of the decarbonisation heat for a particular limestone, even in a relative scale, has been published yet. In the presented research, ten diverse very pure limestone samples from neoproterozoic up to cretaceous were studied by means of light microscopy, powder XRD and differential scanning calorimetry. The samples showed similar mineralogical compositions and relatively close calcite crystallinity including mean crystals size, but very different microstructures and the crystals sizes. DSC was used to measure and compare the heat of different limestones decarbonisation. With the exception of three samples with extremely dense or coarse microstructure, a strong correlation of 0.95 according to the Pearson test between mean size of calcite crystals and the value of the decarbonisation heat was found.
Abstract Inverse magnetic fabrics defined by anisotropy of magnetic susceptibility with the longest principal axis perpendicular to bedding were identified in the studied samples of Ordovician sedimentary rocks from the Barrandian area, Czech Republic. These fabrics are related to ankerite fibers in association with cone‐in‐cone structures. To understand the meaning of such inverse magnetic fabrics for geological interpretations, a new, more detailed classification of inverse magnetic fabrics' types is formulated in this paper. Distinguishing the structural (i.e., shape) and magnetocrystalline anisotropies in rocks, three new (sub)types of magnetic fabrics were defined in this study based on the combination of structural normal/inverse and magnetocrystalline normal/inverse anisotropies. As a result, normal magnetic fabric is extended by new fabric types associated with inverse anisotropy: simple inverse, pure inverse, and pseudo‐normal magnetic fabrics. The studied fibrous ankerite shows simple inverse magnetic fabric, which results from the combination of normal magnetocrystalline and inverse structural anisotropies.
The goal of this work was to apply texture x-ray diffraction analysis to study naturally strained rocks, in which the quantification of main preferred orientation cannot be conducted by the optical methods. This method has mainly been developed for metallography and its application in geology has been very limited so far. Samples of the fine-grained limestone have been collected from an outcrop, in which the direction of tectonic movement has been known. Thus, the tectonic situation could be correlated with the data obtained by XRD texture analysis. Analyses have been done by two devices with different geometry of experiment. The first experiment (Schulz reflection geometry) needed correction for the gain data, because of tilting of the sample, which led to the misalignment of the sample from the x-ray beam direction. The second one (in-plane geometry) has been measured, when the sample has been fixed and rotated, thus the correction was not needed. The results in a form of pole figures reflect the mechanism of deformation. The orientation of cleavage planes of calcite parallel to foliation indicates a cataclastic flow. Thus, the method could be used to study deformation mechanisms. The asymmetry of the results can show sense of shear, but it could also reflect inhomogenities of the samples.
Tell Arbid Abyad is the focus of a Czech archaeological
project(2005-2011), which is associated with the Syrian-Polish
Archaeological Expedition to Tell Arbid. The site, located in
the upper Khabur basin 12 km east of Chagar Bazar in
northeastern Syria, consists of a 2 m high mound that covers an
area of 0.5 ha and dates to the Proto-Halaf to Halaf periods.
This paper summarises the first results of investigations into
the mineral, petrographic and chemical composition of the Late
Neolithic pottery from Tell Arbid Abyad. The provenance of the
examined pottery is also discussed.
This paper constrains the provenance of polished tools used in
the Corded Ware culture (CWC) in Moravia. Based on optical
microscopy, Přichystal and Sebela (1992) suggested the source
for the CWC battle-axes would be the Gogolow-Jordanow Massif in
Lower Silesia (Poland). The present study examines 14
serpentinite tools from archaeological sites of Central
Moravia. We have located the origin of the tools’ raw material
by applying detailed petrographic, geochemical and
petrophysical methods, as well as comparisons with data from
probable serpentinite sources. Possible sources are adjacent to
the Sowie Gory Block (mainly the Gogolow-Jordanow Massif) and
within other areas in Central Europe (Penninic Bernstein
Window, Western Lugicum and the eastern part of the
Moldanubicum). Its most probable source is the Gogolow-Jordanow
Massif, which is a part of the Śleza ophiolite. The tools
resemble the raw material source in several ways: Firstly in
magnetic susceptibility, with an average value of ~40 × 10–3
SI; secondly, in the light yellowish-green patched patinated
surface and very strong serpentinisation with almost no primary
mineral relics; and lastly, in the occurrence of pseudomorphs
filled with opaque minerals, and also parts with magnesite
aggregates, which are quite rare. The main common feature is
the presence of large primary zoned spinels, with Cr- and
Al-rich cores and Fe-rich rims. The conclusions are supported
by the results of bulk-rock chemical analysis, both the raw
material from Lower Silesia and the tools being Mg-rich. In
addition, the shape of some Moravian battle-axes (from
Prusinovice) corresponds to the Śleza type that is believed to
be characteristic of Lower Silesia. The estimated distance of
transport from the source area in Gogolow-Jordanow Massif to
the archaeological sites in Central Moravia is >260 km.
The dyke on the Pohoř hill represents the most southeastern occurrence of Cenozoic volcanic rock in the Bohemian Massif. It has been studied since the second half of the 19th century, when it was discovered during a construction of railroad. Since that time the dyke has been considered to be hidden and there was no actual data about the site. We have carried out a ground magnetic survey to revise the location and shape of the volcanic body. Several boulders of the volcanic rock have been sampled. According to new petrographical and geochemical analyses we have classifi ed the rock from Pohoř as an olivine melilitite.
