Epidote
Image: <a href="//commons.wikimedia.org/wiki/User:Strekeisen" title="User:Strekeisen">Strekeisen</a> (CC BY-SA 4.0)
Mineral NameEpidote
Chemical FormulaCa2(Al,Fe)3(SiO4)3(OH)
Mohs Hardness6.5
Crystal Systemmonoclinic
Lustervitreous
Streak ColorWhite to grayish white
CleavagePerfect on {001}, good on {100}
FractureUneven to conchoidal
Specific Gravity3.4
Colorspistachio green, yellowish-green, brownish-green, black
TransparencyTransparent to translucent
Type LocalityWorldwide, often associated with metamorphic terrains
Mineral GroupSorosilicates
Usescollector's specimens, gemstone, indicator mineral
Associated Mineralschlorite, quartz, feldspar, amphibole, garnet
Raritycommon
Description
This microscopic image, taken under crossed nicols, shows an elongated epidote crystal displaying vibrant blue-yellow interference colors, surrounded by finer-grained, gray chlorite crystals.
Geological Context
Epidote is a common metamorphic mineral formed during regional or contact metamorphism of various rock types, often indicating greenschist to amphibolite facies conditions. It also occurs in hydrothermally altered igneous rocks.
