A Review on the Natural Zeolites of Iran

Varieties of zeolite types found in Mesozoic and early Cenozoic rocks in Iran. The zeolites are divided to four types: 1) sedimentary, 2) hydrothermal, 3) metamorphic, and 4) automorphic analcime in volcanic rocks. Sedimentary zeolites were mostly found in the tuffs of Karaj and Semnan Formations, both of Eocene ages at south of central Alborz, between Tehran and Semnan regions and Central Iran. The zeolitic sequences of Karaj Formation have no evaporates, while those of the Semnan Formation contain some evaporates. Hydrothermal zeolites, widely known as amygdaloidal zeolites, occur at northern part of Central Iran. These zeolites appear in volcanic sequences of Cenozoic of andesitic, trachyandesitic and andesibasaltic compositions. Metamorphic zeolites were distributed among the submarine mafic volcanic rocks of Mesozoic, along the north edge of central Alborz, in Guilan province, and partly in Central Iran. Volcanic rocks of Guilan province experienced burial metamorphism and intense hydrothermal alterations. Automorphic analcimes (phenocryst), with limited distribution, compared to sedimentary and hydrothermal zeolites, occur in Taleghan, at central Alborz, Davazdah-Emam, at north Central Iran, Ardabil, at north of Iran and Shahr-e-Babak of Kerman in the south of Central Iran. Mineralogical variations, chemical composition, variation of the minerals, paragenetic sequences and geneses of the zeolites are presented. There were found no zeolie at Zagross and Kopeh-Dagh regions.