Returning to the properties of natrolite mentioned by Gem Rock, let us consider pyroelectricity and piezoelectricity. "The experiments, made by Mr. C. A. Meek in the Department of Physics of the University of Manchester … showed conclusively that natrolite is weakly pyroelectric, with a single polar axis, the c-axis. … Since this work was completed, F. have found that natrolite is piezoelectric; they do not, however, state which is the piezoelectric axis" . , "investigated single natrolite crystals from the Khibinsk and Lovozersk alkaline massifs of the Kola peninsula. The pyroelectric coefficient γ was measured by the static method using temperature steps of 2-3 K … The dielectric constant ε and the tangent of the angle of dielectric losses were determined". Based on the values of γ and ε and comparing with known values for other materials, Galitskii and Kozlov determined the natrolite as a weak linear pyroelectric.