The presented thesis is focused on the study of fissure zeolitic mineralisation on several localities situated in intermediary rocks of middle Slovakian neovulcanites. The localities of concern are Kremnica in Kremnica mountains, Píla near Žarnovica in Vtáčnik mountains, Sklené Teplice, Žakýl, Banská Štievnica, Hodruša-Hámre, Prenčov and Brehy near Nová Baňa in Štiavnické mountains, Biely Vrch and Slatinské Lazy in Javorie mountains. Following zeolites were identified: laumonite, chabazite, haulandite, stilbite, natrolite and thomsonite. They occured in simple mineral associations, mainly laumonite with calcite and stilbite from Píla or natrolite with thomsonite from Kremnica. From morphologic point of view, laumonite formed prismatic needle-like crystals and accretions according to (100) or was massive; chabazite occured as pseudocubic and often in the form of penetrative accretions; heulandite occured in druses with crystal sizes up to 4 mm. The analyses were focused on crystalochemical study with the aim to determine the contents of exchangable cations or water and to try to interpret their effect on crystalic structure. The dominant cation in all zeolites except natrolite was Ca. Higher contents of K were found in chabazite from Slatinské Lazy, and in laumonite from Píla: up to 0,437 apfu and 0,522 apfu, respectively. Other cations determined by the analyses: Na, Mg, Mn, Sr, Ba, Fe, Ti. The effect of substitution of K and Si/Al ratio on crystalic structure of laumonit was proved.