The title of the course is “Crystallography and mineralogy.” What do these terms mean? The word “crystal” descended from the Greek word “krystallos” which means “transparent ice”. In the Middle ages natural quartz crystals were also called “ice”. Finally, the term “crystal” has been applied to all natural solid forms which have polyhedral shape. In the Russian language this term, but changed a little (we pronounce it like “хрусталь”) is used to designate any kind of transparent quartz and artificial glass whith high lead (Pb) content.