Amethyst is a purple variety of Quartz, and is found in many locations worldwide, including Brazil and Uruguay. Varieties include Chevron Amethyst, which has bands of white Quartz in, and Ametrine. Amethyst first become known as a crystal to protect against drinking and addiction when the Greeks used it as a talisman against drunkenness.
The story told by a French poet goes that the drunken God Dionysus set his tigers on the young Amethysta, and then, realising what he had done, turned her into a giant clear Quartz crystal. His tears of remorse then stained the clear Quartz purple, creating Amethyst.