Preanite

Preanite, a mineral, composed chiefly of silica, alumina, and lime, the silica some times about 50 per cent of the whole; but with small and variable proportions of peroxpe of iron, peroxide of manganese, potash, soda, and water. It is a widely diffused man eral, and although first discovered at the cape of good hope, has been found in great beauty in sonic places on the continent of europe and in scotland.