A study on crystallographic characteristic of Mg-vicariate fassaites

Some relationship occurring by isomorphous change of Al3+ for Mg2+, in the presence of some impurities like iron and titanium ions, were studied. This study tooks shape as a contribution for a mineralogical and geochemical study on the contact paragenesis of Predazzo-Monzoni's area in the northern of Italy. It reveals itself also useful to drawn-up informations about the different influence that some network modifier cations bring into the mutual connection of chain systems, even if these cations are randomly dispersed and in a very few amount. This is useful for chemico-physical evaluations concerning their behaviour in multicomponent silicatic compositions whether in lattice systems as crystals or in random systems as glasses and glazes, very important in the sector of glasses and ceramics where direct informations on cations influence are more and more difficult to make display. Some results are according to some observations displayed in previous studies on amphiboles (Rossi, Ungaretti), where a certain influence of Ti4+ and Fe3+ on some parameters were observed.