There are many species of zeolites, such as Analcime, Chabazite, Clinoptilolite, Faujasite, Ferrierite
, Heulandite, Laumontite, Mordenite.
The very rare zeolite species ferrierite
(well, actually, ferrierite-K and ferrierite-Mg are different species, and it's not yet known which of these the new find represents) is found in attractive specimens pretty much exclusively at the Monastir roadfill quarry on Monte Olladri, near Cagliari, Sardinia, Italy.
Natural zeolites, e.g., ferrierite
(Mimura et al., 1992) and clinoptilolite (Arcoya et al., 1996), as well as synthesized zeolites (usually obtained from fly ash) were studied for sorption of cesium from water solutions (e.g.
This material, however, was found to be unstable for shipping and has been replaced by synthetic ferrierite
zeolite crystals, which are stable under operating conditions.
and henmilite, and a so-called "cherry stone after cordierite"--all modestly priced from [euro]10-60 each.
On a recent trip to Sardinia, Claude Begin (749 Union St., Laval, Quebec H7X 1X7) obtained some very fine gmelinite crystals associated with natrolite from Ittiri, Sassari, and some world-class specimens of ferrierite
from near Monastir, Cagliari.