Help mindat.org|Log In|Register|
Home PageMindat NewsThe Mindat ManualHistory of MindatCopyright StatusManagement TeamContact UsAdvertise on Mindat
Donate to MindatSponsor a PageSponsored PagesTop Available PagesMindat AdvertisersAdvertise on MindatThe Mindat Store
Minerals by PropertiesMinerals by ChemistryRandom MineralSearch by minIDLocalities Near MeSearch ArticlesSearch GlossaryMore Search Options
Search For:
Mineral Name:
Locality Name:
Keyword(s):
 
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
StatisticsThe ElementsMember ListBooks & MagazinesMineral Shows & EventsThe Mindat DirectoryHow to Link to MindatDevice Settings
Photo SearchPhoto GalleriesNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day Gallery

Epidote

This page is currently not sponsored. Click here to sponsor this page.
Formula:
{Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
Colour:
Yellowish-green, green, brownish-green, black
Lustre:
Vitreous, Pearly
Hardness:
6
Specific Gravity:
3.38 - 3.49
Crystal System:
Monoclinic
Name:
Named in 1801 by Rene Just Haüy from the Greek επιδοσιζ ("epidosis"), meaning "increase", in allusion to the crystal characteristic of one longer side at the base of the prism.

Classification of Epidote

Approved, 'Grandfathered' (first described prior to 1959)
9.BG.05a

9 : SILICATES (Germanates)
B : Sorosilicates
G : Sorosilicates with mixed SiO4 and Si2O7 groups; cations in octahedral [6] and greater coordination
58.2.1a.7

58 : SOROSILICATES Insular, Mixed, Single, and Larger Tetrahedral Groups
2 : Insular, Mixed, Single, and Larger Tetrahedral Groups with cations in [6] and higher coordination; single and double groups (n = 1, 2)
16.21.2

16 : Silicates Containing Aluminum and other Metals
21 : Aluminosilicates of Fe and Ca

Physical Properties of Epidote

Vitreous, Pearly
Transparency:
Transparent, Opaque
Colour:
Yellowish-green, green, brownish-green, black
Streak:
Colourless
Hardness:
Tenacity:
Brittle
Cleavage:
Perfect
Perfect on {001}, imperfect on {100}
Fracture:
Irregular/Uneven
Density:
3.38 - 3.49 g/cm3 (Measured)    3.43(3) g/cm3 (Calculated)

Optical Data of Epidote

Type:
Biaxial (-)
RI values:
nα = 1.715 - 1.751 nβ = 1.725 - 1.784 nγ = 1.734 - 1.797
2V:
Measured: 90° to 116°, Calculated: 62° to 84°
Max Birefringence:
δ = 0.019 - 0.046
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
High
Dispersion:
strong r > v
Pleochroism:
Strong
Comments:
X= colourless, pale yellow, pale green
Y= greenish yellow
Z= yellowish green

Chemical Properties of Epidote

Formula:
{Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
IMA Formula:
Ca2Fe3+Al2(Si2O7)(SiO4)O(OH)
Common Impurities:
Al,Mg,Mn

Crystallography of Epidote

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/m
Cell Parameters:
a = 8.8877(14) Å, b = 5.6275(8) Å, c = 10.1517(12) Å
β = 115.383(14)°
Ratio:
a:b:c = 1.579 : 1 : 1.804
Unit Cell V:
458.73 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Crystals prismatic to 35 cm. Fibrous, coarse to finely granular, massive.
Twinning:
On {100}, contact, lamellar, common.

Crystallographic forms of Epidote

Crystal Atlas:
Image Loading
Click on an icon to view
Epidote no.9 - Goldschmidt (1913-1926)
Epidote no.94 - Goldschmidt (1913-1926)
3d models and HTML5 code kindly provided by www.smorf.nl.

Toggle
Edge Lines | Miller Indicies | Axes

Transparency
Opaque | Translucent | Transparent

View
Along a-axis | Along b-axis | Along c-axis | Start rotation | Stop rotation

X-Ray Powder Diffraction

Image Loading

Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Type Occurrence of Epidote

Synonyms of Epidote

Other Language Names for Epidote

Varieties of Epidote

Allanite-Epidote

Epidote enriched with REE and Y transitive to allanite. Its REE+Y content is below 0.5 apfu. Sometimes such epidotes able to be selectively enriched with Eu (as it is on Tsakhirin Khuduk deposit in Mongolian Altai).

Beryllian Epidote

A beryllium-bearing variety of epidote.

Chrome-Pistazite

A chromian Epidote with Fe3+>Al

Rosstrevorite

A fibrous stellate variety of Epidote, from Rosstrevor, Co.Down, Ireland.
(Greg and Lettsom, 1858)

Tawmawite

A Cr-bearing epidote.

Originally reported from Tawmaw (Tawhmaw; Taw Maw), Myitkyina-Mogaung District, Kachin State, Myanmar (Burma).

Withamite

A Mn-rich variety of Epidote.
Originally reported from Glen Coe, Strathclyde (Argyllshire), Scotland, UK.

Yttroepidote

Yttrian Epidote with Y+REE content below 0.5 apfu. Transitive to Allanite-(Y).
First described from Slyudorudnik locality at Southern Ural in 1959.

Relationship of Epidote to other Species

Other Members of this group:
Clinozoisite{Ca2}{Al3}(Si2O7)(SiO4)O(OH)
Epidote-(Sr){CaSr}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
Hancockite{CaPb}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
Mukhinite{Ca2}{Al2V3+}(Si2O7)(SiO4)O(OH)
Niigataite{CaSr}{Al3}(Si2O7)(SiO4)O(OH)
Piemontite{Ca2}{Al2Mn3+}(Si2O7)(SiO4)O(OH)
Piemontite-(Pb){CaPb}{Al2Mn3+}(Si2O7)(SiO4)O(OH)
Piemontite-(Sr){CaSr}{Al2Mn3+}(Si2O7)(SiO4)O(OH)
Tweddillite{CaSr}{Mn3+AlMn3+}(Si2O7)(SiO4)O(OH)
Group Members:
Pistacite {Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
Unnamed (Ga-dominant member of the epidote group) {Ca2}{Al2(Ga,Fe)}(Si2O7)(SiO4)O(OH)

Related Minerals - Nickel-Strunz Grouping

9.BG.XCyprineCa19Cu2+(Al10Mg2)Si18O68(OH)10
9.BG.05bAllanite-(Ce){CaCe}{Al2Fe2+}(Si2O7)(SiO4)O(OH)
9.BG.05bAllanite-(La){CaLa}{Al2Fe2+}(Si2O7)(SiO4)O(OH)
9.BG.05bAllanite-(Y){CaY}{Al2Fe2+}(Si2O7)(SiO4)O(OH)
9.BG.05aClinozoisite{Ca2}{Al3}(Si2O7)(SiO4)O(OH)
9.BG.05bDissakisite-(Ce){CaCe}{Al2Mg}(Si2O7)(SiO4)O(OH)
9.BG.05Dollaseite-(Ce){CaCe}{MgAlMg}(Si2O7)(SiO4)(OH)F
9.BG.05Hancockite{CaPb}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
9.BG.05Khristovite-(Ce){CaCe}{MgAlMn2+}(Si2O7)(SiO4)(OH)F
9.BG.05Mukhinite{Ca2}{Al2V3+}(Si2O7)(SiO4)O(OH)
9.BG.05Piemontite{Ca2}{Al2Mn3+}(Si2O7)(SiO4)O(OH)
9.BG.05Piemontite-(Sr){CaSr}{Al2Mn3+}(Si2O7)(SiO4)O(OH)
9.BG.05bManganiandrosite-(La){Mn2+La}{Mn3+AlMn2+}(Si2O7)(SiO4)O(OH)
9.BG.05Tawmawite{Ca2}{(Al,Fe3+,Cr)3}(Si2O7)(SiO4)O(OH)
9.BG.05Tweddillite{CaSr}{Mn3+AlMn3+}(Si2O7)(SiO4)O(OH)
9.BG.05bFerriallanite-(Ce){CaCe}{Fe3+AlFe2+}(Si2O7)(SiO4)O(OH)
9.BG.05Niigataite{CaSr}{Al3}(Si2O7)(SiO4)O(OH)
9.BG.05Manganiandrosite-(Ce){Mn2+Ce}{Mn3+AlMn2+}(Si2O7)(SiO4)O(OH)
9.BG.05Dissakisite-(La){CaLa}{Al2Mg}(Si2O7)(SiO4)O(OH)
9.BG.05Vanadoandrosite-(Ce){Mn2+Ce}{V3+AlMn2+}(Si2O7)(SiO4)O(OH)
9.BG.05Uedaite-(Ce){Mn2+Ce}{Al2Fe2+}(Si2O7)(SiO4)O(OH)
9.BG.05Epidote-(Sr){CaSr}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
9.BG.05bAllanite-(Nd){CaNd}{Al2Fe2+}(Si2O7)(SiO4)O(OH)
9.BG.05bFerriallanite-(La){CaLa}{Fe3+AlFe2+}(Si2O7)(SiO4)O(OH)
9.BG.05bÅskagenite-(Nd){Mn2+Nd}{Al2Fe3+}(Si2O7)(SiO4)O2
9.BG.10Zoisite{Ca2}{Al3}(Si2O7)(SiO4)O(OH)
9.BG.15MacfalliteCa2Mn3+3(SiO4)(Si2O7)(OH)3
9.BG.15SursassiteMn2+2Al3(SiO4)(Si2O7)(OH)3
9.BG.20Julgoldite-(Fe2+)Ca2Fe2+Fe3+2(Si2O7)(SiO4)(OH)2 · H2O
9.BG.20OkhotskiteCa2(Mn,Mg)(Mn3+,Al,Fe3+)2(Si2O7)(SiO4)(OH)2 · H2O
9.BG.20Pumpellyite-(Fe2+)Ca2Fe2+Al2(Si2O7)(SiO4)(OH)2 · H2O
9.BG.20Pumpellyite-(Fe3+)Ca2(Fe3+,Mg)(Al,Fe3+)2(Si2O7)(SiO4)(OH,O)2 · H2O
9.BG.20Pumpellyite-(Mg)Ca2MgAl2(Si2O7)(SiO4)(OH)2 · H2O
9.BG.20Pumpellyite-(Mn2+)Ca2Mn2+Al2(Si2O7)(SiO4)(OH)2 · H2O
9.BG.20ShuiskiteCa2MgCr2(Si2O7)(SiO4)(OH)2 · 2H2O
9.BG.20Julgoldite-(Fe3+)Ca2Fe3+Fe3+2(Si2O7)(SiO4)O(OH) · H2O
9.BG.20Pumpellyite-(Al)Ca2Al3(Si2O7)(SiO4)(OH,O)2 · H2O
9.BG.20PoppiiteCa2(V3+,Fe3+,Mg)(V3+,Al)2(Si2O7)(SiO4)(OH,O)2 · H2O
9.BG.20Julgoldite-(Mg)Ca2MgFe3+2(Si2O7)(SiO4)(OH)2 · H2O
9.BG.25GanomalitePb9Ca5Mn(Si2O7)4(SiO4)O
9.BG.30RustumiteCa10(Si2O7)2(SiO4)(OH)2Cl2
9.BG.35Vesuvianite(Ca,Na,☐)19(Al,Mg,Fe3+)13(☐,B,Al,Fe3+)5(Si2O7)4(SiO4)10(OH,F,O)10
9.BG.35WiluiteCa19(Al,Mg)13(B,☐,Al)5(Si2O7)4(SiO4)10(O,OH)10
9.BG.35ManganvesuvianiteCa19Mn3+(Al,Mn3+,Fe3+)10(Mg,Mn2+)2(Si2O7)4(SiO4)10O(OH)9
9.BG.35FluorvesuvianiteCa19(Al,Mg,Fe2+)13(Si2O7)4(SiO4)10O(F,OH)9
9.BG.40Vyuntspakhkite-(Y)(Y,Yb)4Al2.5-1.5(Si,Al)1.5-2.5(SiO4)4O(OH)7
9.BG.45DellaiteCa6Si3O11(OH)2
9.BG.50Gatelite-(Ce)CaCe3Al2(Al,Mg)(Mg,Fe2+,Al)(Si2O7)(SiO4)3(O,F)(OH,O)2
9.BG.55Västmanlandite-(Ce)Ce3CaMg2Al2Si2O15(OH)2F

Related Minerals - Hey's Chemical Index of Minerals Grouping

16.21.1EsseneiteCaFe3+[AlSiO6]
16.21.3Ferro-tschermakite☐{Ca2}{Fe2+3Al2}(Al2Si6O22)(OH)2
16.21.4Ferro-aluminotschermakite☐{Ca2}{Fe2+3Al2}(Al2Si6O22)(OH)2
16.21.5Ferri-tschermakite☐{Ca2}{Mg3Fe3+2}(Al2Si6O22)(OH)2
16.21.6Ferro-Ferri-tschermakite☐{Ca2}{Fe2+3Fe3+2}(Al2Si6O22)(OH)2
16.21.7Alumino-ferro-hornblende☐{Ca2}{Fe2+4Al}(AlSi7O22)(OH)2
16.21.8Pumpellyite-(Fe2+)Ca2Fe2+Al2(Si2O7)(SiO4)(OH)2 · H2O
16.21.8Pumpellyite-(Fe3+)Ca2(Fe3+,Mg)(Al,Fe3+)2(Si2O7)(SiO4)(OH,O)2 · H2O

Related Minerals - Dana Grouping (8th Ed.)

58.2.1a.1Allanite-(Ce){CaCe}{Al2Fe2+}(Si2O7)(SiO4)O(OH)
58.2.1a.2Allanite-(La){CaLa}{Al2Fe2+}(Si2O7)(SiO4)O(OH)
58.2.1a.3Allanite-(Y){CaY}{Al2Fe2+}(Si2O7)(SiO4)O(OH)
58.2.1a.4Clinozoisite{Ca2}{Al3}(Si2O7)(SiO4)O(OH)
58.2.1a.5Dissakisite-(Ce){CaCe}{Al2Mg}(Si2O7)(SiO4)O(OH)
58.2.1a.6Dollaseite-(Ce){CaCe}{MgAlMg}(Si2O7)(SiO4)(OH)F
58.2.1a.8Hancockite{CaPb}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
58.2.1a.9Khristovite-(Ce){CaCe}{MgAlMn2+}(Si2O7)(SiO4)(OH)F
58.2.1a.10Mukhinite{Ca2}{Al2V3+}(Si2O7)(SiO4)O(OH)
58.2.1a.11Piemontite{Ca2}{Al2Mn3+}(Si2O7)(SiO4)O(OH)
58.2.1a.12Piemontite-(Sr){CaSr}{Al2Mn3+}(Si2O7)(SiO4)O(OH)

Other Information

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

Epidote in petrology

An essential component of (items highlighted in red)
Common component of (items highlighted in red)

References for Epidote

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Dana, E.S. (1892) Dana's system of mineralogy, 6th. edition. New York: 516-521.
Gottardi G. (1954) Dati ed osservazioni sulla struttura dell'epidoto. Periodico di Mineralogia: 245-250.
Seki, Y. (1959) Relation between chemical composition and lattice constants of epidote. American Mineralogist: 44: 720-730.
Chatterjee, N.D. (1962) Vesuvianite-epidote paragenesis as a product of greenschist facies of regional metamorphism in the Western Alps. Beiträge zur Mineralogie und Petrographie: 8: 432-439.
Keith, T.E.C., Muffler L.J.P., Cremer, M. (1968) Hydrothermal epidote formed in the Salton Sea geothermal system, California. American Mineralogist: 53: 1635-1644.
Dollase, W.A. (1971) Refinement of the crystal structures of epidote, allanite and hancockite. American Mineralogist: 56: 447-464.
Gabe, E.J., Portheine, J.C., Whitlow, S.H. (1973) A reinvestigation of the epidote structure: confirmation of the iron location. American Mineralogist: 58: 218-223.
Sakai, C., Higashino, T., Enami, M. (1984) REE-bearing epidote from Sanbagawa pelitic schists, central Shikoku, Japan. Geochemical Journal: 18: 45-53.
Deer, W.A., Howie, R.A., Zussman, J. (1986) Rock-forming minerals, (2nd edition), v. 1B, disilicates and ring silicates: 44: 134.
Kvick, Å, Pluth, J.J., Richardson, J.W. Jr., Smith, J.V. (1988) The ferric iron distribution and hydrogen bonding in epidote: a neutron diffraction study at 15 K. Acta Crystallographica: 44: 351-355.
Holland, T.J.B., Redfern, S.A.T., Pawley, A.R. (1996) Volume behavior of hydrous minerals at high pressure and temperature: II. Compressibilities of lawsonite, zoisite, clinozoisite and epidote. American Mineralogist: 81: 341-348.
Gieré, R., Sorensen, S.S. (2004) Allanite and other REE-rich epidote-group minerals. In: Epidotes (A. Liebscher & G. Franz, editors). Reviews in Mineralogy and Geochemistry: 56: 431-493.
Armbruster, T., Bonazzi, P., Akasaka, M., Bermanec, V., Chopin, C., Gieré R., Heuss-Assbichler, S., Liebscher, A., Menchetti, S., Pan, Y., Pasero, M. (2006) Recommended nomenclature of epidote-group minerals. European Journal of Mineralogy: 18: 551-567.

Internet Links for Epidote

mindat.org URL:
https://www.mindat.org/min-1389.html
Please feel free to link to this page.
Specimens:
The following Epidote specimens are currently listed for sale on minfind.com.

Localities for Epidote

Mineral and/or Locality  
Mindat.org is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2017, except where stated. Mindat.org relies on the contributions of thousands of members and supporters.
Privacy Policy - Terms & Conditions - Contact Us Current server date and time: July 26, 2017 13:43:22 Page generated: July 25, 2017 00:22:39
Go to top of page