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monocliniccommonSilicates (Sorosilicates, Epidote Group)

Epidote

Ca2(Al,Fe)3(SiO4)3(OH)

A yellowish-green, elongated lens of epidote is embedded within a darker, fine-grained amphibole-epidote schist, showing clear signs of deformation and a sigma structure.

Epidote Physical Properties

Mohs Hardness

Crystal System

monoclinic

Luster

vitreous

Streak Color

white to grayish white

Cleavage

perfect on {001}, good on {100}

Fracture

uneven to conchoidal

Specific Gravity

3.35

Colors

pistachio green, yellowish-green, brownish-green, blackish-green, brown, black

Transparency

translucent

Type Locality

Knappenwand, Untersulzbachtal, Salzburg, Austria (famous for crystals)

Mineral Group

Silicates (Sorosilicates, Epidote Group)

Uses

collector's specimens, minor gemstone, indicator mineral for metamorphic conditions

Associated Minerals

amphibole, quartz, feldspar, garnet, chlorite, actinolite, calcite

Rarity

common

Geological Context

Epidote commonly forms during regional or contact metamorphism of mafic igneous rocks or calcareous sediments. This specimen, found in an amphibole-epidote schist, indicates formation under medium-grade metamorphic conditions and subsequent deformation by shear stress.

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Related Specimens

Gibbsite

Realgar

Andradite

Azurite-Malachite

Quartz

Hornblende