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Andradite

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José Bonifácio de Andrada e Silva
Formula:
Ca3Fe23+(SiO4)3
System:
Isometric
Colour:
Yellow, greenish yellow ...
Lustre:
Adamantine, Resinous, Dull
Hardness:
6½ - 7
Name:
Named in 1868 by James Dwight Dana in honor of José Bonifácio de Andrada e Silva [June 13, 1763 Santos, Brazil - April 6, 1838 Niterói, Brazil], Brazilian mineralogist.

Classification of Andradite

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
8/A.08-110
9.AD.25

9 : SILICATES (Germanates)
A : Nesosilicates
D : Nesosilicates without additional anions; cations in [6] and/or greater coordination
51.4.3b.1

51 : NESOSILICATES Insular SiO4 Groups Only
4 : Insular SiO4 Groups Only with cations in [6] and >[6] coordination
14.22.9

14 : Silicates not Containing Aluminum
22 : Silicates of Fe and Ca
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First Recorded Occurrence of Andradite

Year of Discovery:
1868

Occurrences of Andradite

Geological Setting:
In skarns from contact metamorphosed impure limestones or calcic igneous rocks; in chlorite schists and serpentinites; in alkalic igneous rocks, then typically titaniferous.

Physical Properties of Andradite

Adamantine, Resinous, Dull
Diaphaneity (Transparency):
Transparent, Translucent
Colour:
Yellow, greenish yellow to emerald-green, dark green; brown, brownish red, brownish yellow; grayish black, black; may be sectored
Streak:
White
Hardness (Mohs):
6½ - 7
Tenacity:
Brittle
Fracture:
Irregular/Uneven, Conchoidal
Density:
3.8 - 3.9 g/cm3 (Measured)    3.859 g/cm3 (Calculated)

Crystallography of Andradite

Crystal System:
Isometric
Class (H-M):
m3m (4/m 3 2/m) - Hexoctahedral
Space Group:
Ia3d
Cell Parameters:
a = 12.056Å
Unit Cell Volume:
V 1,752.31 ų (Calculated from Unit Cell)
Z:
8
Morphology:
Commonly well-crystallized dodecahedra, trapezohedra, or combinations, to 5 cm. Also granular to massive.

Crystal Structure

Structure
Reference
Novak G A Gibbs G V (1971) The crystal chemistry of the silicate garnets sample An. American Mineralogist 56:791-823.

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Unit Cell | Structure | Polyhedra

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More Crystal Structures
Click here to view more crystal structures at the American Mineralogist Crystal Structure Database
X-Ray Powder Diffraction:
Image Loading

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

Optical Data of Andradite

Type:
Isotropic
RI values:
n = 1.887
Max Birefringence:
δ = 0.000 - Isotropic minerals have no birefringence
Surface Relief:
Very High
Type:
Anisotropic
Anisotropism:
Typically weak

Chemical Properties of Andradite

Formula:
Ca3Fe23+(SiO4)3
Essential elements:
All elements listed in formula:
Common Impurities:
Ti,Cr,Al,Mg

Relationship of Andradite to other Species

Series:
Forms a series with Grossular (see here)
Forms a series with Schorlomite (see here)
Other Members of Group:
AlmandineFe32+Al2(SiO4)3
BerzeliiteNaCa2(Mg,Mn2+)2(AsO4)3
BitikleiteCa3SbSn(AlO4)3
BlythiteMn32+Mn23+[SiO4]3
Calderite(Mn2+,Ca)3(Fe3+,Al)2(SiO4)3
DzhuluiteCa3SbSnFe33+O12
ElbrusiteCa3U6+ZrFe23+Fe2+O12
GoldmaniteCa3V23+(SiO4)3
GrossularCa3Al2(SiO4)3
HenritermieriteCa3(Mn3+,Al)2(SiO4)2(OH)4
HutcheoniteCa3Ti2(SiAl2)O12
IrinarassiteCa3Sn2Al2SiO12
KatoiteCa3Al2(SiO4)3-x(OH)4x
KerimasiteCa3Zr2(SiO4)(Fe3+O4)2
KhohariteMg3Fe23+(SiO4)3
KimzeyiteCa3(Zr,Ti)2((Si,Al,Fe3+)O4)3
KnorringiteMg3Cr2(SiO4)3
MajoriteMg3(Fe2+,Si,Al)2(SiO4)3
Menzerite-(Y){(Y,REE),(Ca,Fe2+)}3{(Mg,Fe2+),(Fe3+,Al)}2[SiO4]3
Momoiite(Mn2+,Ca)3V23+(SiO4)3
MorimotoiteCa3(Ti,Fe2+,Fe3+)2((Si,Fe3+)O4)3
Palenzonaite(Ca,Na)3CaMn22+(VO4)3
PyropeMg3Al2(SiO4)3
SchäferiteCa2NaMg2(VO4)3
SchorlomiteCa3(Ti,Fe3+)2((Si,Fe3+)O4)3
SkiagiteFe32+Fe23+[SiO4]3
SpessartineMn32+Al2(SiO4)3
ToturiteCa3Sn2(SiO4)(Fe3+O4)2
UsturiteCa3SbZr(Fe3+O4)3
UvaroviteCa3Cr2(SiO4)3
YafsoaniteCa3Zn3(TeO6)2
9.AD.05LarniteCa2SiO4
9.AD.10Calcio-olivineCa2SiO4
9.AD.15MerwiniteCa3Mg(SiO4)2
9.AD.20BredigiteCa7Mg(SiO4)4
9.AD.25AlmandineFe32+Al2(SiO4)3
9.AD.25Calderite(Mn2+,Ca)3(Fe3+,Al)2(SiO4)3
9.AD.25GoldmaniteCa3V23+(SiO4)3
9.AD.25GrossularCa3Al2(SiO4)3
9.AD.25HenritermieriteCa3(Mn3+,Al)2(SiO4)2(OH)4
9.AD.25HibschiteCa3Al2(SiO4)3-x(OH)4x
9.AD.25HydroandraditeCa3Fe23+(SiO4)3-x(OH)4x
9.AD.25KatoiteCa3Al2(SiO4)3-x(OH)4x
9.AD.25KimzeyiteCa3(Zr,Ti)2((Si,Al,Fe3+)O4)3
9.AD.25KnorringiteMg3Cr2(SiO4)3
9.AD.25MajoriteMg3(Fe2+,Si,Al)2(SiO4)3
9.AD.25MorimotoiteCa3(Ti,Fe2+,Fe3+)2((Si,Fe3+)O4)3
9.AD.25PyropeMg3Al2(SiO4)3
9.AD.25SchorlomiteCa3(Ti,Fe3+)2((Si,Fe3+)O4)3
9.AD.25SpessartineMn32+Al2(SiO4)3
9.AD.25UvaroviteCa3Cr2(SiO4)3
9.AD.25Wadalite(Ca,Mg)6(Al,Fe3+)4((Si,Al)O4)3O4Cl3
9.AD.25HoltstamiteCa3(Al,Mn3+)2(SiO4)2(OH)4
9.AD.25KerimasiteCa3Zr2(SiO4)(Fe3+O4)2
9.AD.25ToturiteCa3Sn2(SiO4)(Fe3+O4)2
9.AD.25Momoiite(Mn2+,Ca)3V23+(SiO4)3
9.AD.25EltyubyuiteCa12Fe103+Si4O32Cl6
9.AD.25HutcheoniteCa3Ti2(SiAl2)O12
9.AD.30Coffinite(U4+,Th)(SiO4)1-x(OH)4x
9.AD.30HafnonHfSiO4
9.AD.30Thorite(Th,U)SiO4
9.AD.30ZirconZrSiO4
9.AD.30StetinditeCe4+SiO4
9.AD.35HuttoniteThSiO4
9.AD.35Tombarthite-(Y)Y4(Si,H4)4O12-x(OH)4+2x
9.AD.40EulytineBi4(SiO4)3
9.AD.45ReiditeZrSiO4
14.22.1HedenbergiteCaFe2+Si2O6
14.22.2Pyroxferroite(Fe,Mn,Ca)SiO3
14.22.3 Ferro-akermaniteCa2FeSi2O7
14.22.4KirschsteiniteCaFe2+SiO4
14.22.5TungusiteCa4Fe2Si6O15(OH)6
14.22.6Ferro-actinolite☐{Ca2}{Fe52+}(Si8O22)(OH)2
14.22.7IlvaiteCaFe22+Fe3+(Si2O7)O(OH)
14.22.8Julgoldite-(Fe2+)Ca2(Fe2+,Mg)(Fe3+,Al)2(Si2O7)(SiO4)(OH)2 · H2O

Other Names for Andradite

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.

References for Andradite

Reference List:
Manning, P.G. (1967), The optical absorption spectra of some andradites and the identification of 6A, → 4A, 4E(G) transition in octahedrally bonded Fe+3:Canadian Jour. Earth Sci.: 4: 1039-1047.

Howie, R.A., A.R. Wooley, J.H. Scoon, R.C. Tyler & J.N. Walsh (1968), The role of titanium and the effect of TiO2 on the cell size, refractive index, and specific gravity in the andradite-melanite-schorlomite series: Min. Magazine: 36: 775-790.

Isaacs, T. (1968), Titanium substitution in andradites: Chem. Geol.: 3: 219-222.

Manning, P.G. & D.C. Harris (1970), Optical absorption and electron-microprobe studies of some high-Ti andradites: Can. Min: 10: 260-271.

American Mineralogist: 74: 1307-1316.

Armbruster, Th., Birrer, J., Libowitzky, E., Beran, A. (1998): Crystal chemistry of Ti-bearing andradites, European Journal of Mineralogy, 10, 907-921.

Badar, M. A., Akizuki, M. and Hussain, S. (2010): Optical anomaly in iridescent andradite from the Sierra Madre Mountains, Sonora, Mexico. Can. Mineral. 48, 1195-1203.

Adamo, Ilaria; Gatta, G. Diego; Rotiroti, Nicola; Diella, Valeria; Pavese, Alessandro (2011): Green andradite stones: gemmological and mineralogical characterisation. European Journal of Mineralogy 23, 91-100.

Internet Links for Andradite

Specimens:
The following Andradite specimens are currently listed for sale on minfind.com.

Localities for Andradite

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
Mineral and/or Locality  
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