Zeolites are also known as permutits and in greek it means boiling stone. Zeolites are naturally occurring hydrated sodium alumino silicate minerals (like Na2O.Al2O3.xSiO2.yH2O, where x=2 to 10 and y = 2 to 6) capable of exchanging reversibly its sodium ions for hardness producing ions in water. So, the formula for exhausted permutit is hydrated sodium alumino silicate. (Na2Al2Si2O8,xH2O)