Amygdaloidal, Cavity and Fracture-Filling Zeolites of East Robat-Karim, North Central Iran

Volcanic rocks at the east Robat-Karim, 10 km south-west of Tehran, contain varieties of amygdale, vein, veinlet and patchy zeolites. The identified zeolites are analcime, tetranatrolite, natrolite, stilbite, scolecite, mesolite, laumontite, mordenite heulandite/clinoptilolite and phillipsite. Smectite, chlorite, opal, quartz and calcite are usually accompanied with these zeolites. We report laumontite, phillipsite and mordenite, for the first time, in amygdales in the Central Iran. Based on the evidences such as occurrences oftetranatrolite, chlorite, veins and intense alteration of host rocks, chlorite coating of amygdales; it is concluded that the zeolites are formed hydrothermally in the east Robat-Karim volcanic rocks.