Epidote is a common mineral formed during low grades of metamorphism and hydrothermal activity. It is particular common in metamorphosed basalts and gabbros where it replaces plagioclase, pyroxene and olivine. It can also be found in schists and marbles.

Epidote can be found in many locations through the entire world (including Colorado), but gem quality crystals are somewhat rare. Epidote can be quite a fibrous, nearly opaque mineral that would only yield catseyes or cabachons so faceted gems are rare.