Epidote is a group of closely related minerals, but when it comes to the gem trade, epidote typically refers to only gem-quality green epidote, which is considered a very rare find, especially when found in faceted gemstone form. Epidote is a complex form of calcium aluminum iron silicate in which both the calcium and aluminum ion contents are replaced by other metals (manganese, ferric iron or yttrium and cerium metals). Since epidote is an alteration gemstone, it can exhibit a very wide variance in composition and chemical formula. Depending on the exact levels of iron, manganese and other substances, some epidote gemstones may be classified under various trade names or in many cases, as their own distinct mineral species. Clinozoisite is a white to pink form of gem-quality epidote that has a very a similar chemical composition to zoisite (best known as violet tanzanite). Piemontite is a red manganese epidote often opaque in form. Tawmawite is a dark green chromium-rich variety of epidote mined from Burma. Unakite is an altered form and variety of granite that shares characteristic inclusions of epidote, which is often used in cabochon and beaded gemstone jewelry.