The isomorphous substitution of Al3+ and/or Fe3+ cations into the erionite zeolite framework were studied through periodic density functional theory computations. Taking as reference the Mulliken charges for siliceous framework computed in previous work (Antunez-Garcia et al. in J Mol Struct 1059:232-238, 2014), the present results show that the basicity of ERI zeolite increases when those cations are introduced into the framework. It was also observed that when at least two Si4+ cations are isomorphically substituted by Fe3+ in the unit cell of the erionite zeolite, it acquires magnetic properties. The results show that a specific net-spin polarization (up or down) could be correlated with particular configurations of erionite zeolite, containing ferric iron.