CONDITIONS FOR CRYSTALLIZATION OF VARIOUS FORMS OF CHRYSOBERYL CRYSTAL-GROWTH

On the basis of the experimental data on chrysoberyl crystal growth, t he conditions have been revealed, under which growth twinning is impos sible. The established dependence of the dominance of some growth form s over others under various conditions of crystallization medium permi tted elucidation of the causes of crystal twinning. The latter is show n to depend primarily on beryllium and aluminium concentrations in min eral forming impurities. The criteria of the origin and growth of well formed colored individuals have been found, which are of great intere st for their practical use.