Abstract: A process of modifying the porosity of an aluminosilicate or silica whose porosity is not amenable to modification by acid extraction. The process involves contacting said aluminosilicate or silica with an alkali aluminate, and then extracting the aluminate-treated material with an extraction agent so as to form the porosity-modified aluminosilicate or silica. The process is applicable to zeolites which are unreactive under acid extraction conditions, e.g. ferrierite, and applicable to zeolites which are structurally unstable under acid extraction conditions, such as the mineral bikitaite. Mesoporous compositions are disclosed, including a mesoporous ferrierite and a mesoporous zeolite DCM-3.