Browsing by Subject "iron compounds"

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Związki żelaza jako pigment w wybranych piaskowcach karpackich
(Data obrony: 2010-07-20) Drzymalski, Łukasz
Wydział Geologii, Geofizyki i Ochrony Środowiska
A phenomenon commonly observed in sandstones containing Fe-minerals is formation of layered zones of clearly different colouration, connected with various concentrations of iron compounds. Similar processes have also been described in historic buildings built of sandstones with iron cement or Fe-rich compounds. Understanding the processes of weathering sandstones rich in Fe-minerals, conditions of the mobilization and precipitation of secondary compounds and their types is important for any action aimed at conservation of the building stones. The sandstone rocks in the Polish Flysch Carpathians are particularly convenient for studying the weathering processes, in the natural outcrops having been long time exposed to the influence of the atmospheric factors. The aim of this study was to investigate the occurrence, concentration and types of the Fe-compounds in the sandstones sampled in the Polish Flysch Carpathians, as well as their impact on the colour and structure of these rocks. Diversified colouration observed in distinct layers is connected with various concentrations of the Fe-compounds. Most often they occur in form of: crystalline oxides or hydroxides, such as goethite and haematite, aluminium silicates, and amorphous phases of the ferrihydrite type. A very significant impact on the sandstone layer colouration is due to have their occurrence in form of the submicroscopic aggregates. The weathering processes also resulted in formation of secondary minerals, such as jarosite, gypsum, and halite, on the surface of the sandstone rocks.