Zeolites are microporous crystalline aluminosilicates derived from the reaction of volcanic rocks, ash layers and alkaline groundwater. The Atlas of Zeolite Framework Types currently recognizes about 218 different Zeolite structures, of which 40 natural zeolites are known. Natural zeolites are listed by the USA Food and Drug Administration for human consumption (FDA GRAS Listings, 2006) and considered as non-toxic by the World Health Organization’s International Agency for Research on Cancer (IARC, 1997). Moreover, Codex Alimentarius Commission (1999) lists some zeolites as a granted substance in Organic Food Production and Plant Protection. ​ Most of us are familiar with the zeolites used in water softener systems. The zeolite core of the water softener absorbs large amounts of metals like calcium and magnesium from the water. Periodically, the zeolite in your water softener is flushed with highly concentrated salt water to flush out the metal ions and regenerate the zeolite for more absorption. The most common forms of zeolites used in water softeners are the natural aluminosilicates, gluconites (i.e. greensand), and synthetic permutite.