Epidote
Image: Didier Descouens (CC BY 4.0)
Mineral NameEpidote
Chemical FormulaCa₂Al₂Fe³⁺(SiO₄)(Si₂O₇)O(OH)
Mohs Hardness6
Crystal Systemmonoclinic
Lustervitreous
Streak Colorwhite to grayish white
Cleavageperfect on {001}, good on {100}
Fractureuneven
Specific Gravity3.35
Colorspistachio green, olive green, yellowish green, brownish green
Transparencytranslucent
Type LocalityLe Cornillon, Bourg d'Oisans, Isère, Rhône-Alpes, France
Mineral Groupsilicates
Usescollector's specimens, minor gemstone, indicator mineral
Associated Mineralsquartz, feldspar, garnet, actinolite, calcite
Raritycommon
Description
This specimen displays a dense, radiating aggregate of olive-green to brownish-green epidote crystals, forming a textured, sparkling surface on a matrix. The individual crystals are acicular to prismatic, creating a striking visual effect.
Geological Context
Epidote is a common mineral in regionally metamorphosed rocks like schists and gneisses, and in contact metamorphic aureoles. It forms under medium-grade metamorphic conditions and is also found in hydrothermally altered igneous rocks.
