Epidote
“Pistachio green crystals”
Epidote is a calcium aluminum iron silicate mineral recognized by its distinctive pistachio to yellowish-green color. It commonly forms during low-grade metamorphism and hydrothermal alteration and is one of the most useful indicator minerals for understanding the geological history of a region.
calcium aluminum iron sorosilicate (Ca₂(Al,Fe)₃(SiO₄)(Si₂O₇)O(OH))
Knappenwand (Austria — world-famous crystals), Prince of Wales Island (Alaska, USA), Pakistan, Baja California (Mexico), Norway
6-7
The Knappenwand locality in the Austrian Alps produces some of the world's finest epidote crystals — some specimens reach over 15 cm long with gemmy, transparent green color.
Test Your Knowledge
Why is epidote commonly found in metamorphic rocks that formed at medium-grade conditions?
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