Zeolites have been recognized for more than 200 years, but only during the middle of the
20th century have attracted the attention of scientists and engineers who demonstrated their
technological importance in several fields. Although most of the effort was devoted to synthetic
zeolites, in recent years increasing attention has been directed towards natural zeolites, whose status
changed from that of museum curiosity to an important mineral commodity. Natural zeolites forming
the corresponding group of tectosilicate mineral subclass, due to their specific crystal chemical
characteristics providing the unique ion exchange and molecular sieve properties, are known as
effective adsorbents and catalysts. The zeolites are highly rigid under dehydration as well as under
various aggressive surroundings actions. The molecular sieving and other physico-chemical properties
of the zeolites can be managed by the thermal or chemical treatment. Such features provide the
effective and wide utilization of these materials in industry, agriculture, medicine, environmental
protection and other fields. Synthesized analogues of the natural zeolites are usually applied in
different technological processes, and the low output price conditioned by a subsurface location of
massive deposits of natural zeolites throughout the world make them significantly more available for
a wide utilization. Main fields of industrially important zeolite rocks are presented by clinoptilolite (or
mordenite, chabazite, phillipsite, etc.) tuffs and are connected with volcanic formations.
Keywords: Natural zeolites, volcanic tuffs, clinoptilolite (natural) zeolite, ion
exchange, dealumination, physical (thermal) activation, thermal activation,
chemical treatments, biological treatments, catalytic applications, catalytic
processes, adsorption process, heterogeneous catalysis, mineral acids, C-C bonds,
acetaldehyde, formaldehyde, aldol condensation, acrolein, crotonaldehyde.
