What is Epidote?
Epidote is a calcium-aluminium-iron sorosilicate recognised by pistachio-green colour, strong relief and elongated prismatic crystals.
Mineralogy and structure
Reference formula: Ca2Al2FeSi3O12(OH). Epidote has a monoclinic structure built from isolated and paired silicate groups. Iron content strongly influences colour, and pistachio green is characteristic but not diagnostic by itself.
Colour and appearance
Typical colours include pistachio green, yellow-green, brown, black. The usual prismatic, granular, columnar habit and vitreous, resinous lustre are useful descriptive features, but colour alone is not diagnostic.
Formation and localities
Epidote forms in or is associated with regional and contact metamorphism, hydrothermal veins, skarns and altered mafic rocks. Important documented localities include Austria, Pakistan, Mali, Norway, Italy, Mexico and the United States.
Collecting and care
Usually durable for display, but crystals can chip along cleavage and should be protected from knocks.
Epidote in popular symbolism
Modern crystal guides sometimes associate Epidote with symbolic themes based on colour or collecting tradition. These associations are cultural interpretations, not mineralogical or medical properties.
