Chemical Variation, Mode of Occurrence and Genesis of Cavity-Vein-Zeolites of Kuh-e-Aradeh, North Central Iran

Zoned sequence of zeolites in amygdales, show a succession of tetranatrolite, analcime, natrolite, mesolite, stilbite-Ca, epistilbite, scolecite and heulandite-Ca from high to low temperatures and from outermost to innermost portions of the amygdales, respectively. Formation of primary calcite deposition takes place at a higher temperature than the rest of minerals in the amygdales. The sequences of formation of non-zeolitic minerals are chlorite, opal, quartz, pyrolusite and hematite. The zeolites were probably formed as a result of late stage hydrothermal activity from hot waters. The host rocks of the zeolites of the region vary from rhyodacite, trachyandesite, andesite to andesibasalt. Rarely zeolites weret formed in the basaltic host rocks in this region.