The term zeolite was coined in 1756 by the Swedish mineralogist Axel Fredrik Cronstedt, who observed that during the rapid heating of the mineral stilbite, large amounts of steam are produced from the water, which is absorbed by the mineral. Based on this fact, he named this mineral zeolite, from the Greek word ze\u014d, meaning to boil and stone. Zeolites are aluminosilicate members of a family of microporous solids known as molecular sieves. To date, more than 45 species of natural zeolites have been identified and described. However, only seven of these, namely the minerals mordenite, clinoptilolite, ferriarite, habazite, erionite, phyllite and analkymite, occur in sufficient quantities to be considered exploitable materials. For nutritional, pharmaceutical, medicinal, medical, environmental, aquatic, agricultural and industrial uses, the zeolite type-HEU (clinoptilolite-eulandite) content is required to be greater than 75%.<\/p>\n\n
Zeolites occur as geological reserves around the world, especially in rocks that partially or in their entirety have volcanic origins. This explains the frequent presence in geographical areas with volcanic activity. They derive from the hydrothermal alteration of various aluminosilicate minerals such as feldspar and feldspathoid covering mostly small cavities, cracks and joints basaltic lavas and less commonly granites and gneisses.<\/p>\n\n
These are mainly deposits formed by the transformation of pyroclastic rocks in open hydrological systems.<\/p>\n