Geology Home Page
Roger Weller, geology instructor
Chemical Group: silicate
Chemical Formula: HCa2(Al,Fe)3Si3O13
Color: pistachio-green, pea soup green, brownish green, greenish black, black, red,
gray, grayish white
Transparency: transparent to opaque
Hardness: 6 to 7
Specific Gravity: 3.25 to 3.5
Cleavage: one direction
Crystal Forms and Habits:
Crystals are prismatic.
Epidote commonly forms as a thin coating along fractures in rocks.
Epidote also is commonly found in massive form.
Mineral Associations: a common metamorphic mineral
Identifying Characteristics: its distinct yellow-green color and massive nature
Uses: when combined with pinkish orange feldspar, as a gemstone (unakite)
Prince of Wales island
Wickenburg, Jerome. Bagdad, Castle Hot Springs, Cave Creek
Inyo, Mono, El Dorado, Fresno, Kern, and San Diego Counties
Lake Superior region
Taos, Orogrande, Silver City, Santa Fe
Spruce Pine, Bakersville, Burnsville, Dyartsville
Enchanted Rock,Texas Hill Country
Royal Front (unakite)
Greene, Nelson, Albemarle, and Rockbridge counties
Toxicity: when-swallowed- low when inhaled- moderate
A stone containing green epidote and salmon-colored feldspar is
a gemstone known as unakite.
An alternative name for epidote is pistacite (in reference to the color
of the pistachio nut).