National Repository of Grey Literature 86 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Alluvial gold placers from Klínec area - morphology and nature of gold
Fox, Simon ; Zachariáš, Jiří (advisor) ; Štědrá, Veronika (referee)
The search for economically viable gold deposits remains a significant pursuit requiring skilled expertise. The first part of the thesis establishes essential concepts related to gold ore deposits and placer gold, including its elemental properties, genesis in an orogenic environment, transportation by natural forces, and deposition in a fluvial setting. The study particularly focuses on the Klínec area in Central Bohemia and offers an insight into the geological region characterized by a Neoproterozoic basement uplifted during the late Miocene due to tectonic movements that played an integral role in the placer gold deposition. The historical context of gold mining in this Bohemian region is also presented. The practical segment of this thesis aims to establish connections between statistical and observational methods and the relationship between placer gold and its orogenic gold deposit. The methodology involves fieldwork for collecting gold particles which were then subjected to optical observation and microscopic photography. Morphological features, particularly sphericity and roundness, are analysed to identify trends indicating proximity to the primary gold source. The findings reveal that gold particles closer to the primary source exhibit sharper angularity, larger grain size, and greater...
Mineralogy of VMS-type deposits and their comparison with samples from the Tisova deposit
Bulyžkin, Rodion ; Zachariáš, Jiří (advisor) ; Dolníček, Zdeněk (referee)
Mineralogy of VMS-type deposits and their comparison with samples from the Tisová deposit Rodion Bulyžkin Abstract Volcanogenic Massive Sulphides (VMS) deposits are a specific type of mineral deposits that are currently an important source of mineral resources. They are essential for their high metal content used for the industrial and energy sectors of the world economy and the future development of human society. They are rich in both, base and precious metals and therefore deposits of this type are of strategic importance. Their study and exploration provide important information on the formation of mineral resources and the evolution of submarine volcanic systems. They also contribute to a better understanding of geological processes and the evolution of our planet, and makes it possible to discover new reserves of metals (especially copper and zinc ores, which are used in industry, such as electronics, building materials and energy) that can be exploited for future generations. The formation of these deposits is linked to processes that take place near subduction zones or where tectonic plates collide. During these processes, hot solutions and mineral-rich gaseous phases react with the surrounding rocks and seawater. Such contact results in rapid cooling of the hydrothermal fluid and...
Genetic relationships between intrusions of porphyry dykes and formation of Au ores at Petrov and Bohuliby
Petrov, Ivan ; Zachariáš, Jiří (advisor) ; Slobodník, Marek (referee)
This master's thesis is focused on genetic relationships between Au-bearing ores and associated granodiorite porphyry dykes in Petrov and Bohuliby area in southwestern part of the Jílové ore district. Subvolcanic rocks with hydrothermally induced alteration and Au/bearing mineralization were characterized by petrography, mineralogy and crystallochemistry. Mutual genetic and textural relationships of studied materials were examined as well and were validated by biotite, arsenopyrite and chlorite empirical geothermometry. First identified generation of sulfide mineralization was formed at 360řC and consist of arsenopyrite, galenite and native gold. At circa 274řC porphyry mineral association was chloritized, and chlorite gangue crystallized. Second generation of sulfide mineralization precipitated at 264řC. Anomalous absence of Bi-Te-S phases and scheelite in hydrothermal paragenesis is important indicator of contrasting conditions of mineralization at the studied areas and main zone of the Jílové ore deposit. Based on acquired data, granodiorite porphyry dikes were categorized to two separate genetic types, which have mutual origin in deep magma chamber of Central Bohemian Plutonic Complex but intruded non-contemporaneously.
High purity silica materials: genesis, properties, and their potential resources in the Czech Republic
Tichý, Daniel ; Přikryl, Richard (advisor) ; Zachariáš, Jiří (referee)
Quartz and other siliceous materials are among the most widely used industrial raw materials. Demand for high-purity silica increased during past decades, specifically due to its growing use in the photovoltaic energy or electronic/electrical industries. Strict requirements on the purity of the feedstock, together with very complex processing technology, narrow down the choice of potential sources suitable for industrial extraction and use. This bachelor thesis provides an overview of the existing knowledge concerning the formation, properties, and processing of industrially exploitable deposits, and the market policy of high-purity quartz raw materials. This comprehensive overview is followed by a section that focuses on deposits and potential sources of high-purity quartz raw materials in the Czech Republic (Bohemian Massif). This part was elaborated on the basis of publicly available archival sources (final exploration reports or reserve calculations), available in the Czech Geological Survey - Geofond.
Metallogeny of selected gold deposits of the Bohemian Massif
Němec, Matěj ; Zachariáš, Jiří (advisor) ; Slobodník, Marek (referee) ; Sejkora, Jiří (referee)
The overall text was processed on the bases of two separate articles published recently by the author and collective, and one more article, which is currently submitted for editorial. All the articles in full are attached at the end of this work. First article is trying to decipher the evolution of formation of the Sb-Au deposits Krásná Hora-Milešov, and Příčovy. The second article is in very detail dedicated to transition of gold to aurostibite and formation of Au-Ag-Sb(S) phases at Krásná Hora-Milešov Sb-Au deposit. The third article is looking into genesis of the Voltýřov Au deposit. The Krásná Hora-Milešov and Příčovy deposits are examples of in the Bohemian Massif unique Sb-Au deposits. The deposits consist of vein type mineralization and ore is represented by massive to disseminated stibnite and disseminated gold postdating stibnite. The quartz gangue vein system is developed in Těchnice granodiorite, within robust E-W trending fault zone, and in close association with same oriented repeatedly tectonically rejuvenated lamprophyre dikes. The fluid inclusions (FI) study suggested formation of stibnite at ~250 to ~130 řC and gold at about ~200 to ~130 řC from low salinity aqueous fluids. The bulk of quartz precipitated from the same type of fluid. Disseminated arsenopyrite along with early quartz...
Genetic relationships between intrusions of porphyry dykes and formation of Au ores at Petrov and Bohuliby
Petrov, Ivan ; Zachariáš, Jiří (advisor) ; Slobodník, Marek (referee)
This master's thesis is focused on genetic relationships between Au-bearing ores and associated granodiorite porphyry dykes in Petrov and Bohuliby area in southwestern part of the Jílové ore district. Subvolcanic rocks with hydrothermally induced alteration and Au/bearing mineralization were characterized by petrography, mineralogy and crystallochemistry. Mutual genetic and textural relationships of studied materials were examined as well and were validated by biotite, arsenopyrite and chlorite empirical geothermometry. First identified generation of sulfide mineralization was formed at 360řC and consist of arsenopyrite, galenite and native gold. At circa 274řC porphyry mineral association was chloritized, and chlorite gangue crystallized. Second generation of sulfide mineralization precipitated at 264řC. Based on acquired data, granodiorite porphyry dikes were categorized to two separate genetic types, which have mutual origin in deep magma chamber of Central Bohemian Plutonic Complex but intruded non-contemporaneously.
The content and binding of silver in galena
Němec, Matěj ; Goliáš, Viktor (advisor) ; Zachariáš, Jiří (referee)
Galena as the most important silverbearing ore is found in almost every Ag deposit. If the content of Ag is higher than 0,5 wt. % then is called galena solid solution - PbSss. The galena Ag has two forms of occurrence - inclusions and isomorphic silver. Aboat ninety percent of galena Ag is product of retrograde proces of PbSss cooling. These are matildite (AgBiS2), miargyrite (AgSbS2), diaforite (PbAg3Sb3S8), freislebenite (AgPbSbS3), pyrargyrite (Ag3SbS3) aramayoite (Ag(Sb,Bi)S2), freibergite (Ag12Sb4S13), gustavite (AgPbBi3S6) etc. The smaller amounth of isomorphic Ag is substituted as 2Ag+ = PbII+ . Under the usual conditions of deposition (200 - 300řC) , the solubility of Ag2S is to low. The content of Ag in galena under these conditions is not higher then 0,4 mol. % at 615řC. Most of the isomorphic Ag is bound in coupled substitution Ag+ + Bi III+ /Sb III+ = 2 PbII+ . In this case the content of Ag in PbS can be as high as 9 wt. % at 350 - 400řC. At the deposites where wasn't activated this Bi/Sb - Pb coupled substitution the content of Ag in galena is very low. The content of trace elements of Ag, Bi and Sb can also influence the galena crystal habit. Galena rich on Bi ususaly creates octahedral crystals. Galena with a higher content of Ag and Sb usualy creates cubic crystals.
Distribution of sulfur isotopes in peat bogs
Haluzová, Eva ; Mihaljevič, Martin (advisor) ; Zachariáš, Jiří (referee)
The goal of this barchelor thesis is to describe the influence of human activity to sulphur cycle and monitoring processes and changes in this cycle with the assistance of specific sulphur isotopes. The first part describes sulphur and its compounds, then appearence in environment and its total cycle. The next part is focused on specific sulphur isotopes and thein application in studies of soils and peats. The final part summarizes total results and informations of human activity and it's influence on the sulphur cycle.

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2 Zachariáš, Jan
2 Zachariáš, Jindřich
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