(a) Illustration of the structure of an ideal potassium chabazite crystal, highlighting the eight-membered oxygen ring (8MR) which sets the nominal pore aperture diameter to be 3.8 Å (distance ...

THE ‘molecular-sieve’ properties of chabazite, a zeolite occurring in basaltic rocks, have been studied extensively. Molecules such as argon (diameter 3.84 A.) and methane (4.25 A.) are ...