Epidote is a calcium aluminum iron sorosilicate mineral. It is an abundantly high prismatic mineral often found in marble. It’s name comes from the Greek word "epidosis", meaning increase or addition due to one side being larger than the other. Epidote has two different meanings to the word, one being the name of a group of silicate minerals with generally the same chemical formula, this is known as the "Epidote Group." Frequent minerals found within this group are amphiboles, feldspars, quartz, and chlorite. The other meaning of Epidote is the most common mineral found within the Epidote Group. The green in Unakite is Epidote, along with feldspar and quartz. Sometimes Epidote can be mistaken for Tourmaline.