Amethyst is found in a geode. Geodes are made from volcanic lava materials and form crystals on the sides from a mixture of periotic elements. Volcanos are made by sudation (sudation occurs when two plates hit each other and one is more dense and falls into the lithosphere making molten materials come through and makes a volcano.) Amethyst is made from quartz.
Amethyst is the birthstone of February which can be found in geodes. Geodes are formed from molten material. Geodes are found by lava on the crust. The Greeks wore amethyst in belief it would prevent intoxication.