Amethyst is the most popular variety of quartz crystals that is considered the most powerful and protective stone. It is a semiprecious violet stone that is often used in jewelry and it has strong healing and cleansing powers. The world’s most important amethyst deposits are usually found in the fractures and cavities of igneous rocks. In Brazil and Uruguay large amounts of amethyst are found in the cavities of basalt flows. Amethyst is the birthstone for February, and known as the Zodiac stone for pisces.