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Almandine

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Formula:
Fe2+3Al2(SiO4)3
Colour:
Deep red, brownish red, red-violet, black
Lustre:
Vitreous, Resinous
Hardness:
7 - 7½
Specific Gravity:
4.318
Crystal System:
Isometric
Name:
Named in 1546 by Georgius Agricola [Georg Bauer] for Alabanda in Turkey, an ancient gem cutting center, presumably where almandine was fashioned into gemstones.
Garnet Group. Almandine-Pyrope Series, Almandine-Spessartine Series.

Most common garnet. Occurs in metamorphic and pegmatitic rocks.

Visit gemdat.org for gemological information about Almandine.


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Classification of AlmandineHide

Approved, 'Grandfathered' (first described prior to 1959)
9.AD.25

9 : SILICATES (Germanates)
A : Nesosilicates
D : Nesosilicates without additional anions; cations in [6] and/or greater coordination
51.4.3a.2

51 : NESOSILICATES Insular SiO4 Groups Only
4 : Insular SiO4 Groups Only with cations in [6] and >[6] coordination
16.17.1

16 : Silicates Containing Aluminum and other Metals
17 : Aluminosilicates of Fe

Physical Properties of AlmandineHide

Vitreous, Resinous
Transparency:
Transparent, Translucent
Colour:
Deep red, brownish red, red-violet, black
Comment:
may be sectored
Streak:
White
Hardness:
7 - 7½ on Mohs scale
Tenacity:
Brittle
Parting:
On {110}
Fracture:
Sub-Conchoidal
Density:
4.318 g/cm3 (Measured)    4.313 g/cm3 (Calculated)

Optical Data of AlmandineHide

Type:
Isotropic
RI values:
n = 1.83
Max Birefringence:
δ = 0.000 - Isotropic minerals have no birefringence
Surface Relief:
Very High
Comments:
Anomalously biaxial.

Chemical Properties of AlmandineHide

Formula:
Fe2+3Al2(SiO4)3

Crystallography of AlmandineHide

Crystal System:
Isometric
Class (H-M):
m3m (4/m 3 2/m) - Hexoctahedral
Space Group:
Ia3d
Cell Parameters:
a = 11.526 Å
Unit Cell V:
1,531.21 ų (Calculated from Unit Cell)
Z:
8
Morphology:
Typically well-formed dodecahedra or trapezohedra, to 1 m; also in rounded grains and massive.

X-Ray Powder DiffractionHide

Image Loading

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

Type Occurrence of AlmandineHide

Synonyms of AlmandineHide

Other Language Names for AlmandineHide

Basque:Almandino
Czech:Almandin
Dutch:Almandien
French:Almandin
Galician:Alabandina
Hungarian:Almandin
Italian:Almandino
Lithuanian:Almandinas
Polish:Almandyn
Serbian (Cyrillic Script):Алмандин
Simplified Chinese:铁铝榴石
贵榴石
Slovenian:Almandin
Spanish:Almandita
Swedish:Almandin
Traditional Chinese:鐵鋁榴石
貴榴石

Varieties of AlmandineHide

DhanrasiteA variety of pyralmandine, Garnet group. Stannian garnets, in particular stannian pyrope-almandine.

Originally reported from Dhanras Hills, Gaya District, Bihar, India.
Star GarnetA variety of almandine exhibiting a four-rayed or rarely six-rayed star due to oriented inclusions of rutile. The Idaho state gemstone.

Relationship of Almandine to other SpeciesHide

Other Members of this group:
AndraditeCa3Fe3+2(SiO4)3Iso. m3m (4/m 3 2/m) : Ia3d
Berzeliite(NaCa2)Mg2(AsO4)3Iso. m3m (4/m 3 2/m) : Ia3d
Bitikleite Group
BlythiteMn2+3Mn3+2[SiO4]3
Calderite(Mn2+,Ca)3(Fe3+,Al)2(SiO4)3Iso.
GoldmaniteCa3V3+2(SiO4)3Iso.
GrossularCa3Al2(SiO4)3Iso. m3m (4/m 3 2/m) : Ia3d
HenritermieriteCa3(Mn3+,Al)2(SiO4)2(OH)4Tet. 4/mmm (4/m 2/m 2/m) : I41/acd
HutcheoniteCa3Ti2(SiAl2)O12Iso. m3m (4/m 3 2/m) : Ia3d
IrinarassiteCa3Sn2Al2SiO12 Iso. m3m (4/m 3 2/m) : Ia3d
KatoiteCa3Al2(SiO4)3-x(OH)4xIso.
KerimasiteCa3Zr2(SiO4)(Fe3+O4)2Iso. m3m (4/m 3 2/m) : Ia3d
KhohariteMg3Fe3+2(SiO4)3
KimzeyiteCa3(Zr,Ti)2((Si,Al,Fe3+)O4)3Iso.
KnorringiteMg3Cr2(SiO4)3Iso.
MajoriteMg3(Fe2+,Si,Al)2(SiO4)3Iso.
Menzerite-(Y){(Y,REE),(Ca,Fe2+)}3{(Mg,Fe2+),(Fe3+,Al)}2[SiO4]3Iso. m3m (4/m 3 2/m) : Ia3d
Momoiite(Mn2+,Ca)3V3+2(SiO4)3Iso. m3m (4/m 3 2/m) : Ia3d
MorimotoiteCa3(Ti,Fe2+,Fe3+)2((Si,Fe3+)O4)3Iso.
Palenzonaite(Ca,Na)3CaMn2+2(VO4)3Iso. m3m (4/m 3 2/m) : Ia3d
PyropeMg3Al2(SiO4)3Iso.
SchäferiteCa2NaMg2(VO4)3Iso.
SchorlomiteCa3(Ti,Fe3+)2((Si,Fe3+)O4)3Iso.
SkiagiteFe2+3Fe3+2[SiO4]3
SpessartineMn2+3Al2(SiO4)3Iso. m3m (4/m 3 2/m) : Ia3d
ToturiteCa3Sn2(SiO4)(Fe3+O4)2Iso. m3m (4/m 3 2/m) : Ia3d
UM1984-37-SiO:CrMnMn2+3(Cr3+,Mn3+)2Si3O12
UvaroviteCa3Cr2(SiO4)3Iso. m3m (4/m 3 2/m) : Ia3d
YafsoaniteCa3Zn3(TeO6)2Iso. m3 (2/m 3)
Forms a series with:

Common AssociatesHide

Albite-Anorthite SeriesFeldspar Group.
Amphibole SupergroupAX2Z5((Si,Al,Ti)8O22)(OH,F,Cl,O)2
AndalusiteAl2(SiO4)O
BiotiteA series or subgroup of the Mica Group.
Chlorite GroupA group of mostly monoclinic (also triclinic or orthorhombic) micaceous phyllosilicate minerals with a structure ...
Cordierite(Mg,Fe)2Al3(AlSi5O18)
HematiteFe2O3
KyaniteAl2(SiO4)O
Pyroxene GroupA large group of inosilicate (chain silicate) minerals with the general formula ABSi2O6.
SillimaniteAl2(SiO4)O
StauroliteFe2+2Al9Si4O23(OH)
Associated Minerals Based on Photo Data:
Quartz126 photos of Almandine associated with Quartz on mindat.org.
Muscovite125 photos of Almandine associated with Muscovite on mindat.org.
Biotite75 photos of Almandine associated with Biotite on mindat.org.
Staurolite74 photos of Almandine associated with Staurolite on mindat.org.
Schorl58 photos of Almandine associated with Schorl on mindat.org.
Microcline27 photos of Almandine associated with Microcline on mindat.org.
Albite-Anorthite Series24 photos of Almandine associated with Albite-Anorthite Series on mindat.org.
Albite18 photos of Almandine associated with Albite on mindat.org.
Fluorapatite17 photos of Almandine associated with Fluorapatite on mindat.org.
Beryl16 photos of Almandine associated with Beryl on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

9.AD.05LarniteCa2SiO4Mon.
9.AD.10Calcio-olivineCa2SiO4Orth. mmm (2/m 2/m 2/m)
9.AD.15MerwiniteCa3Mg(SiO4)2Mon. 2/m : P21/b
9.AD.20BredigiteCa7Mg(SiO4)4Orth.
9.AD.25AndraditeCa3Fe3+2(SiO4)3Iso. m3m (4/m 3 2/m) : Ia3d
9.AD.25Calderite(Mn2+,Ca)3(Fe3+,Al)2(SiO4)3Iso.
9.AD.25GoldmaniteCa3V3+2(SiO4)3Iso.
9.AD.25GrossularCa3Al2(SiO4)3Iso. m3m (4/m 3 2/m) : Ia3d
9.AD.25HenritermieriteCa3(Mn3+,Al)2(SiO4)2(OH)4Tet. 4/mmm (4/m 2/m 2/m) : I41/acd
9.AD.25HibschiteCa3Al2(SiO4)3-x(OH)4xIso. m3m (4/m 3 2/m) : Ia3d
9.AD.25HydroandraditeCa3Fe3+2(SiO4)3-x(OH)4x
9.AD.25KatoiteCa3Al2(SiO4)3-x(OH)4xIso.
9.AD.25KimzeyiteCa3(Zr,Ti)2((Si,Al,Fe3+)O4)3Iso.
9.AD.25KnorringiteMg3Cr2(SiO4)3Iso.
9.AD.25MajoriteMg3(Fe2+,Si,Al)2(SiO4)3Iso.
9.AD.25MorimotoiteCa3(Ti,Fe2+,Fe3+)2((Si,Fe3+)O4)3Iso.
9.AD.25PyropeMg3Al2(SiO4)3Iso.
9.AD.25SchorlomiteCa3(Ti,Fe3+)2((Si,Fe3+)O4)3Iso.
9.AD.25SpessartineMn2+3Al2(SiO4)3Iso. m3m (4/m 3 2/m) : Ia3d
9.AD.25UvaroviteCa3Cr2(SiO4)3Iso. m3m (4/m 3 2/m) : Ia3d
9.AD.25Wadalite(Ca,Mg)6(Al,Fe3+)4((Si,Al)O4)3O4Cl3Iso. 4 3m : I4 3d
9.AD.25HoltstamiteCa3(Al,Mn3+)2(SiO4)2(OH)4Tet. 4/mmm (4/m 2/m 2/m) : I41/acd
9.AD.25KerimasiteCa3Zr2(SiO4)(Fe3+O4)2Iso. m3m (4/m 3 2/m) : Ia3d
9.AD.25ToturiteCa3Sn2(SiO4)(Fe3+O4)2Iso. m3m (4/m 3 2/m) : Ia3d
9.AD.25Momoiite(Mn2+,Ca)3V3+2(SiO4)3Iso. m3m (4/m 3 2/m) : Ia3d
9.AD.25EltyubyuiteCa12Fe3+10Si4O32Cl6Iso. 4 3m : I4 3d
9.AD.25HutcheoniteCa3Ti2(SiAl2)O12Iso. m3m (4/m 3 2/m) : Ia3d
9.AD.30Coffinite(U4+,Th)(SiO4)1-x(OH)4xTet.
9.AD.30HafnonHfSiO4Tet. 4/mmm (4/m 2/m 2/m) : I41/amd
9.AD.30ThoriteTh(SiO4)Tet.
9.AD.30ZirconZr(SiO4)Tet. 4/mmm (4/m 2/m 2/m) : I41/amd
9.AD.30Stetindite-(Ce)Ce(SiO4)Tet. 4/mmm (4/m 2/m 2/m) : I41/amd
9.AD.35HuttoniteThSiO4Mon.
9.AD.35Tombarthite-(Y)Y4(Si,H4)4O12-x(OH)4+2xMon.
9.AD.40EulytineBi4(SiO4)3Iso. 4 3m : I4 3d
9.AD.45ReiditeZrSiO4Tet. 4/m : I41/a

Related Minerals - Dana Grouping (8th Ed.)Hide

51.4.3a.1PyropeMg3Al2(SiO4)3Iso.
51.4.3a.3SpessartineMn2+3Al2(SiO4)3Iso. m3m (4/m 3 2/m) : Ia3d
51.4.3a.4KnorringiteMg3Cr2(SiO4)3Iso.
51.4.3a.5MajoriteMg3(Fe2+,Si,Al)2(SiO4)3Iso.
51.4.3a.6Calderite(Mn2+,Ca)3(Fe3+,Al)2(SiO4)3Iso.

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

16.17.2Macaulayite(Fe,Al)24Si4O43(OH)2Mon.

Other InformationHide

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

References for AlmandineHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Rossman, G.R., Rauch, F., Livi, R., Tombrello, T.A., Shi, C.R., Zhoi, Z.Y. (1988) Nuclear reaction analysis of hydrogen in almandine, pyrope and spessartine garnets. Neues Jahrbuch für Mineralogie Monatshefte: 4: 172-178.
Armbruster, T., Geiger, C.A., Lager, G.A. (1992) Single-crystal X-ray structure study of synthetic pyrope almandine garnets at 100 and 293 K. American Mineralogist: 77: 512-521.
Wang, L., Essene, E.J., Zhang, Y. (2000) Direct observation of immiscibility in pyrope-almandine-grossular garnet. American Mineralogist: 85: 41-46.

Internet Links for AlmandineHide

Localities for AlmandineHide

This 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.

Locality ListShow