Discusses a new method for dating bricks and ceramics, which was discovered during study of the chemical stability of clays used to store nuclear waste. The technique suggested by Waddell and Fountain depends on the diffusion of Ca²⁺ ions from mortar or cement layers into the clay brick. At the interface of the clay brick with the mortar an increase of calcium over time was detected using the electron microprobe. Small sample size and difficulty in achieving accurate measurements with the microprobe may have distorted the results. Thermoluminescence and archaeomagnetic dating methods are also mentioned. See also <i>AATA</i> <b>Vol. 21, Abstract No. 1472</b>, PARIS No. 75536. -- AATA