Epidote

Epidote
General
CategorySorosilicates
Formula
(repeating unit)
{Ca2}{Al2Fe3+}(SiO4)(Si2O7)O(OH)
IMA symbolEp[1]
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H–M symbol)
Space groupP21/m
Identification
ColorPistachio green, yellow-green, greenish black, brownish-green, green, black
Crystal habitPrismatic with striations, fibrous, massive
TwinningOn [100]
Cleavage{001} perfect and {100} imperfect
FractureFlat regular to uneven
Mohs scale hardness6–7
LusterVitreous to resinous
StreakGreyish white
DiaphaneityTransparent to nearly opaque
Specific gravity3.38–3.49
Optical propertiesBiaxial (-)
Refractive indexnα = 1.715–1.751
nβ = 1.725–1.784
nγ = 1.734–1.797
Birefringenceδ = 0.019–0.046
PleochroismStrong
References[2][3][4]

Epidote is a calcium aluminium iron sorosilicate mineral.

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ Epidote. Handbook of Mineralogy
  3. ^ Epidote. Mindat
  4. ^ Epidote. Webmineral

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