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Staurolite

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Formula:
Fe2+2Al9Si4O23(OH)
Colour:
Dark brown, brownish-black, red-brown
Lustre:
Sub-Vitreous, Resinous
Hardness:
7 - 7½
Specific Gravity:
3.74 - 3.83
Crystal System:
Monoclinic
Name:
From Greek "stauros", cross, alluding to the cruciform twins it displays in some cases.
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Classification of StauroliteHide

Approved, 'Grandfathered' (first described prior to 1959)
9.AF.30

9 : SILICATES (Germanates)
A : Nesosilicates
F : Nesosilicates with additional anions; cations in [4], [5] and/or only [6] coordination
52.2.3.1

52 : NESOSILICATES Insular SiO4 Groups and O,OH,F,H2O
2 : Insular SiO4 Groups and O, OH, F, and H2O with cations in [4] and >[4] coordination
16.19.5

16 : Silicates Containing Aluminum and other Metals
19 : Aluminosilicates of Fe and Mg

Physical Properties of StauroliteHide

Sub-Vitreous, Resinous
Transparency:
Translucent
Colour:
Dark brown, brownish-black, red-brown
Streak:
White to grayish
Hardness:
7 - 7½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Distinct/Good
Distinct on {010}
Fracture:
Sub-Conchoidal
Density:
3.74 - 3.83 g/cm3 (Measured)    3.686 g/cm3 (Calculated)

Optical Data of StauroliteHide

Type:
Biaxial (+)
RI values:
nα = 1.736 - 1.747 nβ = 1.740 - 1.754 nγ = 1.745 - 1.762
2V:
Measured: 88° , Calculated: 84° to 88°
Max Birefringence:
δ = 0.009 - 0.015
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
High
Dispersion:
r > v weak
Pleochroism:
Visible
Comments:
X= colourless
Y= pale yellow
Z= golden yellow

Chemical Properties of StauroliteHide

Formula:
Fe2+2Al9Si4O23(OH)
Common Impurities:
Ti,Cr,Mn,Co,Zn,Li,H2O

Crystallography of StauroliteHide

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/m
Setting:
C2/m
Cell Parameters:
a = 7.86 Å, b = 16.6 Å, c = 5.65 Å
β = 90.45°
Ratio:
a:b:c = 0.473 : 1 : 0.34
Unit Cell V:
737.17 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Prismatic crystals
Twinning:
Commonly 60-degree twins on {231}, may be cyclic. Less commonly 90-degree cruciform twins on {031}. On (320) (very rare).
Comment:
Pseudo-orthorhombic

Crystallographic forms of StauroliteHide

Crystal Atlas:
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Staurolite no.12 - Goldschmidt (1913-1926)
Staurolite no.30 - Goldschmidt (1913-1926)
Staurolite no.35 - Goldschmidt (1913-1926)
3d models and HTML5 code kindly provided by www.smorf.nl.

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X-Ray Powder DiffractionHide

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

Synonyms of StauroliteHide

Other Language Names for StauroliteHide

Croatian:Staurolit
Finnish:Stauroliitti
French:Staurotide
Hungarian:Staurolit
Italian:Staurolite
Japanese:十字石
Lithuanian:Staurolitas
Polish:Staurolit
Portuguese:Estaurolita
Simplified Chinese:十字石

Varieties of StauroliteHide

LusakiteA cobalt-bearing variety of Staurolite.
Originally reported from Lusakite occurrence, Lusaka, Lusaka Province, Zambia.
Zincian StauroliteA zinc-bearing variety of staurolite.

Relationship of Staurolite to other SpeciesHide

Other Members of this group:
MagnesiostauroliteMg(Mg,Li)3(Al,Mg)18Si8O44(OH)4Mon. 2/m : B2/m
ZincostauroliteZn2Al9Si4O23(OH)Mon. 2/m : B2/m

Common AssociatesHide

AlmandineFe2+3Al2(SiO4)3
AlmandineFe2+3Al2(SiO4)3
Chloritoid(Fe2+,Mg,Mn2+)Al2(SiO4)O(OH)2
KyaniteAl2(SiO4)O
MuscoviteKAl2(AlSi3O10)(OH)2
QuartzSiO2
TourmalineA(D3)G6(T6O18)(BO3)3X3Z
Associated Minerals Based on Photo Data:
Almandine74 photos of Staurolite associated with Almandine on mindat.org.
Kyanite66 photos of Staurolite associated with Kyanite on mindat.org.
Muscovite22 photos of Staurolite associated with Muscovite on mindat.org.
Quartz12 photos of Staurolite associated with Quartz on mindat.org.
Garnet9 photos of Staurolite associated with Garnet on mindat.org.
Biotite7 photos of Staurolite associated with Biotite on mindat.org.
Paragonite6 photos of Staurolite associated with Paragonite on mindat.org.
Magnetite5 photos of Staurolite associated with Magnetite on mindat.org.
Oligoclase4 photos of Staurolite associated with Oligoclase on mindat.org.
Chlorite Group3 photos of Staurolite associated with Chlorite Group on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

9.AF.05SillimaniteAl2(SiO4)OOrth. mmm (2/m 2/m 2/m)
9.AF.10AndalusiteAl2(SiO4)OOrth. mmm (2/m 2/m 2/m) : Pnnm
9.AF.10KanonaiteMn3+Al(SiO4)OOrth. mmm (2/m 2/m 2/m) : Pnnm
9.AF.15KyaniteAl2(SiO4)OTric. 1 : P1
9.AF.20MulliteAl4+2xSi2-2xO10-xOrth. mmm (2/m 2/m 2/m) : Pbam
9.AF.20Krieselite(Al,Ga)2(GeO4)(OH)2Orth. mmm (2/m 2/m 2/m) : Pnma
9.AF.23BoromulliteAl9BSi2O19Orth. mm2 : Cmc21
9.AF.25YoderiteMg(Al,Fe3+)3(SiO4)2O(OH)Mon. 2/m : P21/m
9.AF.30MagnesiostauroliteMg(Mg,Li)3(Al,Mg)18Si8O44(OH)4Mon. 2/m : B2/m
9.AF.30ZincostauroliteZn2Al9Si4O23(OH)Mon. 2/m : B2/m
9.AF.35TopazAl2(SiO4)(F,OH)2Orth. mmm (2/m 2/m 2/m)
9.AF.40NorbergiteMg3(SiO4)(F,OH)2Orth. mmm (2/m 2/m 2/m)
9.AF.45AlleghanyiteMn2+5(SiO4)2(OH)2Mon. 2/m : P21/b
9.AF.45Chondrodite(Mg,Fe2+)5(SiO4)2(F,OH)2Mon. 2/m : P21/b
9.AF.45ReinhardbraunsiteCa5(SiO4)2(OH,F)2Mon. 2/m : P21/b
9.AF.45KumtyubeiteCa5(SiO4)2F2Mon. 2/m : P21/b
9.AF.45HydroxylchondroditeMg5(SiO4)2(OH)2Mon. 2/m : P21/b
9.AF.50Humite(Mg,Fe2+)7(SiO4)3(F,OH)2Orth. mmm (2/m 2/m 2/m)
9.AF.50Manganhumite(Mn2+,Mg)7(SiO4)3(OH)2Orth.
9.AF.50Unnamed (Ca-analogue of Humite)Ca7(SiO4)4F2Orth. mmm (2/m 2/m 2/m)
9.AF.55ClinohumiteMg9(SiO4)4F2Mon.
9.AF.55SonoliteMn2+9(SiO4)4(OH)2Mon.
9.AF.55HydroxylclinohumiteMg9(SiO4)4(OH)2Mon. 2/m
9.AF.60LeucophoeniciteMn2+7(SiO4)3(OH)2Mon. 2/m : P21/b
9.AF.65Ribbeite(Mn2+,Mg)5(SiO4)2(OH)2Orth.
9.AF.70JerrygibbsiteMn2+9(SiO4)4(OH)2Orth. mmm (2/m 2/m 2/m) : Pbcn
9.AF.75FranciscaniteMn2+6(V5+,☐)2(SiO4)2(O,OH)6Hex.
9.AF.75ÖrebroiteMn2+3(Sb5+,Fe3+)(SiO4)(O,OH)3Hex.
9.AF.75WeliniteMn2+6(W6+,Mg)2(SiO4)2(O,OH)6Trig. 3 : P3
9.AF.80EllenbergeriteMg6(Mg,Ti,Zr,◻)2(Al,Mg)6Si8O28(OH)10Hex.
9.AF.85Chloritoid(Fe2+,Mg,Mn2+)Al2(SiO4)O(OH)2Mon. 2/m : B2/b
9.AF.85MagnesiochloritoidMgAl2(SiO4)O(OH)2Mon. 2/m : B2/b
9.AF.85Ottrélite(Mn2+,Fe2+,Mg)Al2(SiO4)O(OH)2Mon.
9.AF.90PoldervaartiteCaCa[SiO3(OH)](OH)Orth. mmm (2/m 2/m 2/m) : Pbca
9.AF.90OlmiiteCaMn2+[SiO3(OH)](OH)Orth. mmm (2/m 2/m 2/m) : Pbca

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

52.2.3.1MulliteAl4+2xSi2-2xO10-xOrth. mmm (2/m 2/m 2/m) : Pbam
52.2.3.2BoromulliteAl9BSi2O19Orth. mm2 : Cmc21

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

16.19.1IndialiteMg2Al3(AlSi5O18)Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
16.19.2Cordierite(Mg,Fe)2Al3(AlSi5O18)Orth. mmm (2/m 2/m 2/m) : Cccm
16.19.3Sekaninaite(Fe,Mg)2Al3(AlSi5O18)Orth.
16.19.4Ferro-gedrite☐{Fe2+2}{Fe2+3Al2}(Al2Si6O22)(OH)2Orth.
16.19.6Chloritoid(Fe2+,Mg,Mn2+)Al2(SiO4)O(OH)2Mon. 2/m : B2/b
16.19.7AmesiteMg2Al(AlSiO5)(OH)4Tric. 1 : P1
16.19.8Corundophilite(Mg,Fe,Al)6(Si,Al)4O10(OH)8
16.19.9YoderiteMg(Al,Fe3+)3(SiO4)2O(OH)Mon. 2/m : P21/m
16.19.10Delessite(Mg,Fe,Fe,Al)(Si,Al)4O10(O,OH)8
16.19.11Ferrocarpholite(Fe2+,Mg)Al2(Si2O6)(OH)4Orth. mmm (2/m 2/m 2/m) : Ccca
16.19.12Magnesiocarpholite(Mg,Fe2+)Al2(Si2O6)(OH)4Orth.
16.19.13Chamosite(Fe2+,Mg,Al,Fe3+)6(Si,Al)4O10(OH,O)8Mon.
16.19.14Orthochamosite(Fe2+,Mg,Fe3+)5Al(AlSi3O10)(OH,O)8
16.19.15Berthierine(Fe2+,Fe3+,Al)3(Si,Al)2O5(OH)4Mon. m : Bm
16.19.16Odinite(Fe,Mg,Al,Fe,Ti,Mn)2.4((Si,Al)2O5)(OH)4Mon. m : Bm
16.19.17ClinochloreMg5Al(AlSi3O10)(OH)8Mon. 2/m : B2/m
16.19.18Gedrite☐{Mg2}{Mg3Al2}(Al2Si6O22)(OH)2Orth.
16.19.19Magnesiogedrite☐{Mg2}{Mg3Al2}(Al2Si6O22)(OH)2
16.19.20Diabantite(Mg,Fe,Al)6((Si,Al)4O10)(OH)8
16.19.21SudoiteMg2Al3(Si3Al)O10)(OH)8Mon.
16.19.22VermiculiteMg0.7(Mg,Fe,Al)6(Si,Al)8O20(OH)4 · 8H2OMon. 2/m
16.19.23Corrensite(Mg,Fe)9((Si,Al)8O20)(OH)10 · nH2OOrth.

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.

Staurolite in petrologyHide

An essential component of (items highlighted in red)

References for StauroliteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Klaproth, M.H. (1810): Untersuchung des Stauroliths, Beiträge zur chemischen Kenntniss der Mineralkörper, Fünfter Band, Rottmann Berlin, 80-85
Friedel, G. (1904): Étude sur les groupements cristallins. Extrait du Bulletin de la Société de l'Industrie minérale, Quatrième série, Tomes III et IV. Saint-Étienne, Société de l’Imprimerie Théolier J. Thomas et C..
Hurst, V., Donnay, J.D.H., Donnay, G. (1956): Mineral. Mag., 31, 145.
Smith J.V. (1968), American Mineralogist: 53: 1139-1155.
Hollister, L.S. (1970) Origin, mechanism, and consequences of compositional sector zoning in staurolite. American Mineralogist: 55: 742-766.
American Mineralogist (1982): 67: 292-297.
Hemingway, B.S. and Robie, R.A. (1984) Heat capacity and thermodynamic functions for gehlenite and staurolite: with comments on the Schottky anomaly in the heat capacity of staurolite. American Mineralogist: 69: 307-318.
Canadian Mineralogist (1993): 31: 551-582.
Hawthorne, F.C., Ungaretti, L., Oberti, R., Caucia, F., and Callegari, A. (1993): The crystal-chemistry of staurolite II. Order-disorder and the monoclinic → orthorhombic phase transition. Canadian Mineralogist: 31: 583-595.
Canadian Mineralogist (1996): 34: 1051.
Nespolo M. & Ferraris G. (2007): Overlooked problems in manifold twins: twin misfit in zero-obliquity TLQS twinning and twin index calculation. Acta Crystallographica A63, 278-286.

Internet Links for StauroliteHide

Localities for StauroliteHide

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

Mineral and/or Locality  
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