Natural zeolites are aluminosilicates of alkaline and alkaline earth elements.

The basic unit of zeolite structure is tetrahedron and its center represents the silicon and aluminum atom and the forks of tetrahedron are oxygen atoms which are common for two tetrahedrons. In this way tetrahedrons form a set of minerals whose structure is rich in channels and cavities in one, two or three directions. Each mineral is characterized by the size of channel opening and the possibility of sorption of molecules according to their size.

Positive cations are located inside the channels which have neutralized excess of negative charge due to the replacement of Si4+ with AI3+ in the zeolite structure. These cations can be replaced with other cations which is the basic feature of cationic exchange of zeolite.

Unlike other aluminosilicates of similar chemical composition, natural zeolites primarilyhave a specific micro porous crystalline lattice and are characterized by special properties, which relate to the ability to receive and release water without disturbing crystal lattice.

The discovered porous microstructure of zeolite predetermines their useful properties. Freed from water, by heating, zeolites get the ability to receive molecules of various substances, which in their size correspond to the size of micro cavities.

The following zeolite minerals are the most widespread in nature: analcime, clinoptilolite, heulandite, phillipsite. Other minerals (chabazite, mordenite, natrolite, etc.) are less widespread in nature, but can also form deposits of economic importance