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Almandine

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Formula:
Fe32+Al2(SiO4)3
System:
Isometric
Colour:
Deep red, brownish red, ...
Lustre:
Vitreous, Resinous
Hardness:
7 - 7½
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.

Classification of Almandine

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
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
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Type Occurrence of Almandine

Occurrences of Almandine

Geological Setting:
The most common garnet, typically in mica schists and gneisses, from regionally metamorphosed argillaceous sediments and pelites; also in contact metamorphic hornfels. In granites and eclogites; in sedimentary rocks; as a detrital mineral.

Physical Properties of Almandine

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

Crystallography of Almandine

Crystal System:
Isometric
Class (H-M):
m3m (4/m 3 2/m) - Hexoctahedral
Space Group:
Ia3d
Cell Parameters:
a = 11.526Å
Unit Cell Volume:
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 Diffraction:
Image Loading

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

Optical Data of Almandine

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 Almandine

Formula:
Fe32+Al2(SiO4)3
Essential elements:
All elements listed in formula:

Relationship of Almandine to other Species

Series:
Forms a series with Pyrope (see here)
Forms a series with Spessartine (see here)
Other Members of Group:
AndraditeCa3Fe23+(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.25AndraditeCa3Fe23+(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

Other Names for Almandine

Name in Other Languages:
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

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.
Industrial Uses:
Abrasive.

References for Almandine

Reference List:
Rossman, G.R., Rauch, F., Livi, R., Tombrello, T.A., Shi, C.R., and Zhoi, Z.Y. (1988) Nuclear reaction analysis of hydrogen in almandine, pyrope and spessartine garnets. Neues Jahrbuch für Mineralogie Monatshefte: 4: 172-178.

American Mineralogist (1992): 77: 512-521.

Wang, L., Essene, E.J., and Zhang, Y. (2000) Direct observation of immiscibility in pyrope-almandine-grossular garnet. American Mineralogist: 85: 41-46.

Internet Links for Almandine

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

Localities for Almandine

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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