What is Zeolite?

Zeolite is a naturally occurring mineral group consisting of over 50 different minerals. Zeolite deposits were formed millions of years ago, when volcanoes erupted enormous amounts of ash–aluminosilicates of alkaline and alkaline earths. Some of the wind borne ash settled to form thick ash beds. In some cases the ash fell into lakes. In another case water percolated through the ash beds. In both cases, the chemical reaction of volcanic ash and salt water resulted in the formation of natural zeolites.

Made of a special crystalline structure that is porous but remains rigid in the presence of water, zeolites are minerals that are microporous; their pores are smaller than 2 nanometers in diameter. The pores make zeolites highly adsorbent; materials are attracted to the zeolite and adhere to the surface. This is different from absorption, in which the material being absorbed actually changes state. The porous zeolite is host to water molecules and ions of potassium and calcium, as well as a variety of other positively charged ions. Zeolites find wide use as ion-exchange agents, catalysts, and molecular filters in a range of industrial processes. Zeolite - Clinoptilolite

The word "zeolite" comes from the Greek for "boiling stone," because of the early observation that zeolites release water when heated. As their compositions are not fixed, they are examples of nonstoichiometric compounds. As of November 2010, 194 unique zeolite frameworks have been identified, and over 40 naturally occurring zeolite frameworks are known.

Compositionally, zeolites are similar to clay minerals. More specifically, both are alumino-silicates. They differ, however, in their crystalline structure. Many clays have a layered crystalline structure (similar to a deck of cards) and are subject to shrinking and swelling as water is absorbed and removed between the layers. In contrast, zeolites have a rigid, 3-dimensional crystalline structure (similar to a honeycomb) consisting of a network of interconnected tunnels and cages. Water moves freely in and out of these pores but the zeolite framework remains rigid. Another special aspect of this structure is that the pore and channel sizes are nearly uniform, allowing the crystal to act as a molecular sieve. Zeolite Crystals

Zeolites are a large group of natural and synthetic hydrated aluminum silicates. They are characterized by complex three-dimensional structures with large, cagelike cavities that can accommodate sodium, calcium, or other cations (positively charged atoms or atomic clusters); water molecules; and even small organic molecules. Ions and molecules in the cages can be removed or exchanged without destroying the aluminosilicate framework.