There have been a number of studies discussing feasibility criteria of zeolite frameworks 49 and it was previously reported that the known zeolite frameworks lie at the low energydensity edge of the hypothetical SiO 2 database distribution. We can add to these criteria that, in general, feasible zeolite frameworks are characterised by stiff bulk moduli approximately greater than 40 GPa. Moreover, this large-scale analysis suggests that the limits of stiffness and shear resistance are highlighted within the known frameworks, BCT and BIK, with few hypothetical polymorphs found with similar mechanical resistance.