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Staurolite

This page kindly sponsored by Russian Minerals
Formula:
(Fe2+,Mg,Zn)1.5-2Al9(SiO4)4O6(OH,O)2
System:
Monoclinic
Colour:
Dark brown, ...
Hardness:
7 - 7½
Name:
From Greek "stauros", cross, alluding to the cruciform twins it displays in some cases.

Classification of Staurolite

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
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
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Occurrences of Staurolite

Geological Setting:
Amphibolite grade of regionally metamorphosed pelitic rocks.

Physical Properties of Staurolite

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

Crystallography of Staurolite

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/m
Cell Parameters:
a = 7.86Å, b = 16.6Å, c = 5.65Å
β = 90.45°
Ratio:
a:b:c = 0.473 : 1 : 0.34
Unit Cell Volume:
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).

Crystallographic forms of Staurolite

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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Edge Lines | Miller Indicies | Axes

Transparency
Opaque | Translucent | Transparent

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Along a-axis | Along b-axis | Along c-axis | Start rotation | Stop rotation
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 Staurolite

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 Staurolite

Formula:
(Fe2+,Mg,Zn)1.5-2Al9(SiO4)4O6(OH,O)2
Essential elements:
All elements listed in formula:
Common Impurities:
Ti,Cr,Mn,Co,Zn,Li,H2O

Relationship of Staurolite to other Species

Other Members of Group:
Magnesiostaurolite(Mg,Li,Fe2+)1.5-2Al9(SiO4)4O6(OH)2
Zincostaurolite(Zn,Li,Fe2+,Mg)1.5-2Al9(SiO4)4O6(OH)2
9.AF.05SillimaniteAl2(SiO4)O
9.AF.10AndalusiteAl2(SiO4)O
9.AF.10KanonaiteMn3+Al(SiO4)O
9.AF.15KyaniteAl2(SiO4)O
9.AF.20MulliteAl4+2xSi2-2xO10-x
9.AF.20Krieselite(Al,Ga)2(GeO4)(OH)2
9.AF.23BoromulliteAl9BSi2O19
9.AF.25YoderiteMg(Al,Fe3+)3(SiO4)2O(OH)
9.AF.30Magnesiostaurolite(Mg,Li,Fe2+)1.5-2Al9(SiO4)4O6(OH)2
9.AF.30Zincostaurolite(Zn,Li,Fe2+,Mg)1.5-2Al9(SiO4)4O6(OH)2
9.AF.35TopazAl2(SiO4)(F,OH)2
9.AF.40NorbergiteMg3(SiO4)(F,OH)2
9.AF.45AlleghanyiteMn52+(SiO4)2(OH)2
9.AF.45Chondrodite(Mg,Fe2+)5(SiO4)2(F,OH)2
9.AF.45ReinhardbraunsiteCa5(SiO4)2(OH,F)2
9.AF.45KumtyubeiteCa5(SiO4)2F2
9.AF.45HydroxylchondroditeMg5(SiO4)2(OH)2
9.AF.50Humite(Mg,Fe2+)7(SiO4)3(F,OH)2
9.AF.50Manganhumite(Mn2+,Mg)7(SiO4)3(OH)2
9.AF.50Unnamed (Ca-analogue of Humite)Ca7(SiO4)4F2
9.AF.55ClinohumiteMg9(SiO4)4F2
9.AF.55SonoliteMn92+(SiO4)4(OH,F)2
9.AF.55HydroxylclinohumiteMg9(SiO4)4(OH)2
9.AF.60LeucophoeniciteMn72+(SiO4)3(OH)2
9.AF.65Ribbeite(Mn2+,Mg)5(SiO4)2(OH)2
9.AF.70JerrygibbsiteMn92+(SiO4)4(OH)2
9.AF.75FranciscaniteMn62+(V5+,☐)2(SiO4)2(O,OH)6
9.AF.75ÖrebroiteMn32+(Sb5+,Fe3+)(SiO4)(O,OH)3
9.AF.75WeliniteMn62+(W6+,Mg)2(SiO4)2(O,OH)6
9.AF.80EllenbergeriteMg6(Mg,Ti,Zr,◻)2(Al,Mg)6Si8O28(OH)10
9.AF.85Chloritoid(Fe2+,Mg,Mn2+)Al2(SiO4)O(OH)2
9.AF.85MagnesiochloritoidMgAl2(SiO4)O(OH)2
9.AF.85Ottrélite(Mn2+,Fe2+,Mg)Al2(SiO4)O(OH)2
9.AF.90PoldervaartiteCaCa[SiO3(OH)](OH)
9.AF.90OlmiiteCaMn2+[SiO3(OH)](OH)
16.19.1IndialiteMg2Al3(AlSi5O18)
16.19.2Cordierite(Mg,Fe)2Al3(AlSi5O18)
16.19.3Sekaninaite(Fe,Mg)2Al3(AlSi5O18)
16.19.4Ferro-gedrite☐{Fe22+}{Fe32+Al2}(Al2Si6O22)(OH)2
16.19.6Chloritoid(Fe2+,Mg,Mn2+)Al2(SiO4)O(OH)2
16.19.7AmesiteMg2Al(AlSiO5)(OH)4
16.19.8Corundophilite(Mg,Fe,Al)6(Si,Al)4O10(OH)8
16.19.9YoderiteMg(Al,Fe3+)3(SiO4)2O(OH)
16.19.10Delessite(Mg,Fe,Fe,Al)(Si,Al)4O10(O,OH)8
16.19.11Ferrocarpholite(Fe2+,Mg)Al2(Si2O6)(OH)4
16.19.12Magnesiocarpholite(Mg,Fe2+)Al2(Si2O6)(OH)4
16.19.13Chamosite(Fe2+,Mg)5Al(AlSi3O10)(OH)8
16.19.14Orthochamosite(Fe2+,Mg,Fe3+)5Al(AlSi3O10)(OH,O)8
16.19.15Berthierine(Fe2+,Fe3+,Al)3(Si,Al)2O5(OH)4
16.19.16Odinite(Fe,Mg,Al,Fe,Ti,Mn)2.4((Si,Al)2O5)(OH)4
16.19.17Clinochlore(Mg,Fe2+)5Al(AlSi3O10)(OH)8
16.19.18Gedrite☐{Mg2}{Mg3Al2}(Al2Si6O22)(OH)2
16.19.19Magnesiogedrite
16.19.20Diabantite(Mg,Fe,Al)6((Si,Al)4O10)(OH)8
16.19.21Sudoite(Mg,Fe2+)2Al3(AlSi3O10)(OH)8
16.19.22Vermiculite(Mg,Fe,Al)3((Al,Si)4O10)(OH)2 · 4H2O
16.19.23Corrensite(Mg,Fe)9((Si,Al)8O20)(OH)10 · nH2O

Other Names for Staurolite

Name in Other Languages:
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

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 Staurolite

Reference List:
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 Staurolite

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

Localities for Staurolite

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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