TEACHING CRYSTALLOGRAPHY BY COMPUTER AID. G.Polidori^(*), G.Cascarano⁽⁺⁾, C.Giacovazzo⁽⁺⁾, A.Pifferi^(#). ^(*)Dipartimento di Scienze della Terra, Universita', 06100 Perugia, Italy; ⁽⁺⁾Istituto di Ricerca per lo Sviluppo di Metodologie Cristallografiche - CNR c/o Dipartimento Geomineralogico - Campus Universitario Via E. Orabona, 4 - 70125 Bari, Italy; ^(#)Istituto di Strutturistica Chimica `G.Giacomello', CNR, CP 10, 00016 Monterotondo Stazione, Roma, Italy

Several books on general crystallography have been recently published which provide clear description of the fundamentals of Crystallography. However the intrinsic nature of the subject requires non-negligible efforts from the students, who have to mentally reconstruct in threee dimensions what a book can only show in two dimensions. Symmetry operations and their effects in the space, three-dimensional lattices, crystal structures etc., can hardly be dominated unless mental exercise has been made. Even in three dimensions graphic aids can help students to understand the effects of mathematical operations like Fourier transform, convolution, etc.

We started to create a computer based tool to help students to learn and teachers to be more efficient in teaching Crystallography. The guidelines of our work are those described in the recent book "Fundamentals of Crystallography", edited by C.Giacovazzo,Oxford University Press, 1992.

In our intentions this software will be a useful tool for any Department in which Crystallography plays a role.