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Andradite

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Parachinar, Kurram Agency, Federally Administered Tribal Areas (FATA), Pakistan
© 2001 John H. Betts

Show Andradite Photos (302)
Formula:
Ca
 
3
Fe
3+
2
[SiO
 
4
]
 
3
System:IsometricColour:Greenish-yellow, Green, ...
Lustre:Adamantine, Resinous, DullHardness:6½ - 7
Name:For José Bonifácio de Andrada e Silva (1763-1838), Brazilian mineralogist.


Garnet Group. Andradite-Grossular Series, and the Andradite-Schorlomite Series.

Classification of Andradite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:8/A.08-110
Nickel-Strunz 10th (pending) edition ID:9.AD.25

9 : SILICATES (Germanates)
A : Nesosilicates
D : Nesosilicates without additional anions; cations in [6] and/or greater coordination
Dana 8th edition ID:51.4.3b.1

51 : NESOSILICATES Insular SiO4 Groups Only
4 : Insular SiO4 Groups Only with cations in [6] and >[6] coordination
Hey's CIM Ref.:14.22.9

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

Type Locality:Drammen, Buskerud, Norway
Year of Discovery:1868

Occurrences of Andradite

Geological Setting:In skarns from contact metamorphism of impure limestones and calcic igneous rocks. Chlorite schists and serpentinites. Alkaic igneous rocks.

Physical Properties of Andradite

Lustre:Adamantine, Resinous, Dull
Diaphaneity (Transparency):Transparent, Translucent
Colour:Greenish-yellow, Green, Brown, Black, Red, etc.
Streak:White
Hardness (Mohs):6½ - 7
Tenacity:Brittle
Fracture:Irregular/Uneven, Conchoidal
Density (measured):3.8 - 3.9 g/cm3
Density (calculated):3.859 g/cm3

Crystallography of Andradite

Crystal System:Isometric
Class (H-M):m3m (4/m 3 2/m) - Hexoctahedral
Space Group:Ia3d (I41/a 3 2/d)
Cell Parameters:a = 12.056Å
Unit Cell Volume:V 1,752.31 ų (Calculated from Unit Cell)
Z:8
Morphology:Dodecahedra or trapezohedra. Granular, massive.
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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More Crystal Structures
Click here to view more crystal structures at the American Mineralogist Crystal Structure Database
X-Ray Powder Diffraction:
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Radiation - Copper Kα
Data Set:
Horizontal Axis: ° to ° Vertical Axis: % Source Data: Filtered Data: Peaks:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Optical Data of Andradite

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

Chemical Properties of Andradite

Formula:
Ca
 
3
Fe
3+
2
[SiO
 
4
]
 
3
Essential elements:Ca, Fe, O, Si
All elements listed in formula:Ca, Fe, O, Si
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)
Member of:Garnet Group
Related Minerals - Nickel-Strunz Grouping):
9.AD.05Larnite
Ca
 
2
[SiO
 
4
]
9.AD.05Calcio-Olivine
Ca
 
2
[SiO
 
4
]
9.AD.15Merwinite
Ca
 
3
Mg[SiO
 
4
]
 
2
9.AD.20Bredigite
Ca
 
7
Mg[SiO
 
4
]
 
4
9.AD.25Almandine
Fe
2+
3
Al
 
2
[SiO
 
4
]
 
3
9.AD.25Calderite
(Mn
2+
 
,Ca)
 
3
(Fe
3+
 
,Al)
 
2
[SiO
 
4
]
 
3
9.AD.25Goldmanite
Ca
 
3
(V
3+
 
,Al,Fe
3+
 
)
 
2
[SiO
 
4
]
 
3
9.AD.25Grossular
Ca
 
3
Al
 
2
[SiO
 
4
]
 
3
9.AD.25Henritermierite
Ca
 
3
(Mn
3+
 
,Al)
 
2
[(OH)
 
4
|(SiO
 
4
)
 
2
]
9.AD.25Hibschite
Ca
 
3
Al
 
2
[(OH)
 
6-1
|(SiO
 
4
)
 
1.5-2.5
]
9.AD.25Hydroandradite
9.AD.25Katoite
Ca
 
3
Al
 
2
[(OH)
 
8-6
|(SiO
 
4
)
 
1-1.5
]
9.AD.25Kimzeyite
Ca
 
3
(Zr,Ti)
 
2
[(Si,Al,Fe
3+
 
)O
 
4
]
 
3
9.AD.25Knorringite
Mg
 
3
Cr
 
2
[SiO
 
4
]
 
3
9.AD.25Majorite
Mg
 
3
(Fe
2+
 
,Si,Al)
 
2
[SiO
 
4
]
 
3
9.AD.25Morimotoite
Ca
 
3
(Ti,Fe
2+
 
,Fe
3+
 
)
 
2
[(Si,Fe
3+
 
)O
 
4
]
 
3
 (?)
9.AD.25Pyrope
Mg
 
3
Al
 
2
[SiO
 
4
]
 
3
9.AD.25Schorlomite
Ca
 
3
(Ti,Fe
3+
 
)
 
2
[(Si,Fe
3+
 
,Fe
2+
 
)O
 
4
]
 
3
9.AD.25Spessartine
Mn
2+
3
Al
 
2
[SiO
 
4
]
 
3
9.AD.25Uvarovite
Ca
 
3
Cr
 
2
[SiO
 
4
]
 
3
9.AD.25Wadalite
Ca
 
6
(Al,Mg)
 
4
[Cl
 
3
|O
 
4
|{(Si,Al,Fe
3+
 
)O
 
4
}
 
3
]
9.AD.25Holtstamite
Ca
 
3
(Al,Mn
3+
 
)
 
2
(SiO
 
4
)
 
2
(OH)
 
4
9.AD.30Coffinite
(U,Th)[(OH)
 
4x
|(SiO
 
4
)
 
1-x
]
9.AD.30Hafnon
(Hf,Zr)[SiO
 
4
]
9.AD.30Thorite
(Th,U)[SiO
 
4
]
9.AD.30Thorogummite
(Th,U)[(OH)
 
4x
|(SiO
 
4
)
 
1-x
]
9.AD.30Zircon
Zr[SiO
 
4
]
9.AD.35Huttonite
Th[SiO
 
4
]
9.AD.35Tombarthite-(Y)
Y
 
4
[HSiO
 
4
]
 
3
9.AD.40Eulytine
Bi
 
4
[SiO
 
4
]
 
3
9.AD.45Reidite
Zr[SiO
 
4
]
Related Minerals - Hey's Index Grouping:
14.22.1Hedenbergite
CaFe
2+
 
[Si
 
2
O
 
6
]
14.22.2Pyroxferroite
(Fe,Mn,Ca)SiO
 
3
14.22.3 Ferro-akermanite
Ca
 
2
FeSi
 
2
O
 
7
14.22.4Kirschsteinite
CaFe
2+
 
[SiO
 
4
]
14.22.5Tungusite
Ca
 
4
Fe
 
2
Si
 
6
O
 
15
(OH)
 
6
14.22.6Ferro-Actinolite
☐[Ca
 
2
][(Fe
2+
 
,Mg)
 
5
][(OH)
 
2
|Si
 
8
O
 
22
]
14.22.7Ilvaite
CaFe
2+
2
Fe
3+
 
[O|OH|Si
 
2
O
 
7
]
14.22.8Julgoldite-(Fe2+)
Ca
 
2
(Fe
2+
 
,Mg)(Fe
3+
 
,Al)
 
2
[(OH)
 
2
|SiO
 
4
|Si
 
2
O
 
7
] · H
 
2
O

Other Names for Andradite

Synonyms:
AllochroiteAndradite GarnetAplomeJelleliteJellesite
JelletiteKalkeisentongranatPolyadelphinePolyadelphiteRothoffite
German names:
AllochroitAndraditCalcium-FerrigranatKalkeisengranatPolyadelphit
Russian names:
Андрадит
Spanish names:
AllochroitaAndraditaPolyadelphita
Varieties:
BredbergiteDemantoidMelaniteStanniferous AndraditeTopazolite

Other Information

Health Warning: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, Vol. 10, 907-921

Internet Links for Andradite

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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Search for Andradite in the Natural History Museum (London) online catalogue
  • Andradite details from Handbook of Mineralogy (PDF)
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    Localities for Andradite

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