In the whole Adriatic area igneous rock can be only found in the so called volcanic line, which is represented by individual blocks of mentioned rocks that are nowadays lifted above the sea level. Outcrops of these magmatic rocks represent smaller islands of Brusnik, Jabuka and Vis Island. The subject of this thesis are mineralogical and petrological analysis of volcanic rocks from Komiža bay, which is located on the western coast of the island Vis. We examined seven different volcanic rocks from Komiža area with the aim to describe and determine their mineral and chemical composition. We used macroscopic observation, optical microscopy under transmitted light, electron microscopy and X-ray powder diffraction as main analytical techniques. With these methods we determined mineral composition as well as textural and structural characteristics of the investigated rocks. Geochemical composition was determined using X-ray fluorescent spectroscopy. Based on microscopic observations we could identify different phenocrysts in porphyritic texture. Unchanged pyroxens and plagioclases, that are albitizated as a result of hydrothermal metamorphosis, represent relicts of former igneous minerals. Secondary minerals often appear in amygdales. Based on research of similar rocks, we can conclude that, secondary mineral association developed under the prehnite–actinolite facies conditions, which is typically developed in very low to low grade hydrothermal metamorphosis in volcanic island arcs.
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