Piemontite is a mineral that is part of the epidote group, found in metamorphic and hydrothermal rocks. It is a rare mineral, and its color can be reddish-brown, brown, or greenish-brown. Synonyms for piemontite include "piedmontite," "palagonite," and "psilomelane." Palagonite is a term for an altered volcanic rock that contains piemontite, while psilomelane is a term used for a group of black manganese oxide minerals often found in association with piemontite. Piedmontite is similar to piemontite but is a variation of the spelling of the mineral name, named after the Piedmont region of Italy, where it was first discovered.