Amethystis a purple variety of quartz (SiO2) and owes its violet color to irradiation, impurities of iron and in some cases other transition metals, and the presence of other trace elements, which result in complex crystal lattice substitutions. The hardness of the mineral is the same as quartz, thus making it suitable for use in jewelry.
Amethyst was also reputed to control evil thoughts, increase intelligence and render men shrewd in business matters.
For travelers it was worn as a protection from treachery and surprise attacks, kept soldiers from harm and gave them victory over their enemies.
Considered to be a powerful psychic stone of protection against witchcraft and black magic.