Amethyst is a purple variety of quartz (SiO2) and owes its violet color to natural irradiation, iron impurities, and the presence of trace elements, which result in complex crystal lattice substitutions. It’s considered a semi-precious gemstone, and just two centuries ago was considered to have a value on par with diamonds, sapphires and rubies. The largest, and best known amethyst deposit occur in southern Brazil and Uruguay but many localities around the world produce an amazing variety of amethyst crystals and formations.