Fissure zeolite mineralization of the intermediate rocks of Central Slovakian neovolcanites

This contribution summarizes the results of the study of fissure zeolite mineralization at several locations in the intermediate rocks of the Central Slovakian neovolcanites. These locations were monitored: Kremnica, Pila by Zarnovica, Sklene Teplice, Takyl, Banska Stiavnica, Hodrusa-Hamre, Prencov and Brehy by Nova Bana, Biely Vrch and Slatinske Lazy. Zeolites have been identified as follows: laumontite, chabazite, heulandite, stilbite, natrolite and thomsonite. They occurred in simple associations - mainly laumontite with calcite and stilbite from Pila, or natrolite with thomsonit from Kremnica. From the morphological point of view laumontite formed prismatic needle crystals and adhesions according to (100) or it was massive. Chabazite was formed as pseudo-cubic and in a form of interpenetration adhesions. Heulandite featured druses with crystal size up to 4 mm. Analyses focused on crystallo-chemical study to find out the contents of exchangeable cations or of water and try to interpret their influence on the crystal structure. Ca was a dominant cation in all the zeolites except natrolite. Influence of K and of a ratio of Si / Al on structure of laumontite was proved. (author)