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Andalusite

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Formula:
Al2(SiO4)O
System:
Orthorhombic
Colour:
Pink to red brown, ...
Lustre:
Vitreous, Sub-Vitreous, Greasy
Hardness:
6½ - 7½
Name:
Named by Jean-Claude Delamétherie in 1798 for the supposed type locality, "Andalusia region", Spain, although he seems to have been not very familiar with spanish geography and the type locality is not in Andalusia.

Andalusite was first analysed by Werner on specimens coming from Spain. Both Werner and Delamétherie believed that the specimens came from Andalusia, which is why the latter named it "andalusite". However, it seems that the analyzed specimens came from El Cardoso (Guadalajara), a town they erroneously thought to be in Andalusia. Consequently the type locality must be considered El Cardoso, probably the outcrop located in Zahurdon. The error was perpetuated by other later authors, who considered that the origin was the province of Almeria, and remained so in the majority of books, even in modern ones. Furthermore, andalusite had already been known previously, and even been described, in its chiastolite variety, by a Spanish author, Torrubia, in 1754. The description was published in a famous book, "Aparato para la Historia Natural Española", in which aragonite also appears. In both cases the descriptions are accompanied by illustrations that depict both minerals unmistakably. (See the article by Dr. Miguel Calvo, "Minerales que tienen en España su localidad tipo" - http://milksci.unizar.es/miner/mineralesp/tipo.html
Polymorph of:
Isostructural with:

Classification of Andalusite

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
9.AF.10

9 : SILICATES (Germanates)
A : Nesosilicates
F : Nesosilicates with additional anions; cations in [4], [5] and/or only [6] coordination
52.2.2b.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
15.1

15 : Silicates of Aluminum
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First Recorded Occurrence of Andalusite

Geological Setting of First Recorded Material:
Low pressure and low temperature metamorphic rocks.

Occurrences of Andalusite

Geological Setting:
A result of contact metamorphism of argillaceous sediments, also in regionally metamorphosed schists. Rare in granites and pegmatites, which however afford the largest crystals. Detrital in some sandstones.

Physical Properties of Andalusite

Vitreous, Sub-Vitreous, Greasy
Diaphaneity (Transparency):
Transparent, Translucent
Colour:
Pink to red brown, occasionally yellow, green, white, gray rarely violet
Comment:
in thin section, colorless to pink or green.
Streak:
White
Hardness (Mohs):
6½ - 7½
Tenacity:
Brittle
Cleavage:
Distinct/Good
Good on {110}
Poor on {100}
Fracture:
Irregular/Uneven, Sub-Conchoidal
Density:
3.13 - 3.21 g/cm3 (Measured)    3.149 g/cm3 (Calculated)

Crystallography of Andalusite

Crystal System:
Orthorhombic
Class (H-M):
mmm (2/m 2/m 2/m) - Dipyramidal
Space Group:
Pnnm
Space Group Setting:
Pnnm
Cell Parameters:
a = 7.798(7) Å, b = 7.9031(10) Å, c = 5.5566(5) Å
Ratio:
a:b:c = 0.987 : 1 : 0.703
Unit Cell Volume:
V 342.44 ų (Calculated from Unit Cell)
Z:
4
Morphology:
As euhedral crystals or columnar aggregates having nearly square cross sections, commonly elongated parallel to [001], to 20 cm. Crystals may be much interrupted due to intersection with outer minerals. Also fibrous, compact, massive.
Twinning:
On {101} - rare

Crystallographic forms of Andalusite

Crystal Atlas:
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Andalusite no.1 - Goldschmidt (1913-1926)
Andalusite no.10 - Goldschmidt (1913-1926)
Andalusite no.14 - Goldschmidt (1913-1926)
Andalusite no.18 - Goldschmidt (1913-1926)
3d models and HTML5 code kindly provided by www.smorf.nl.

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X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.
X-Ray Powder Diffraction Data:
d-spacingIntensity
5.55 (100)
4.53 (80)
3.93 (30)
3.53 (30)
2.77 (70)
2.27 (30)
2.18 (30)
2.17 (40)
Comments:
ICDD 39-376

Optical Data of Andalusite

Type:
Biaxial (-)
RI values:
nα = 1.629 - 1.640 nβ = 1.633 - 1.644 nγ = 1.638 - 1.650
2V:
Measured: 73° to 86°, Calculated: 80° to 84°
Birefringence:
0.009
Max Birefringence:
δ = 0.009 - 0.010
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
Moderate
Dispersion:
r < v strong
Pleochroism:
Weak
Comments:
X= reddish pink
Y=Z= greenish yellow
Comments:
Iron substitution may dramatically increase RI and birefringence.

Chemical Properties of Andalusite

Formula:
Al2(SiO4)O
Essential elements:
All elements listed in formula:

Relationship of Andalusite to other Species

Series:
Forms a series with Kanonaite (see here)
9.AF.05SillimaniteAl2(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.30Staurolite(Fe2+,Mg,Zn)1.5-2Al9(SiO4)4O6(OH,O)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)
15.2KyaniteAl2(SiO4)O
15.3SillimaniteAl2(SiO4)O
15.4MulliteAl4+2xSi2-2xO10-x
15.5PyrophylliteAl2(Si4O10)(OH)2
15.6DickiteAl2(Si2O5)(OH)4
15.7NacriteAl2(Si2O5)(OH)4
15.8KaoliniteAl2(Si2O5)(OH)4
15.9Metahalloysite
15.10HalloysiteAl2(Si2O5)(OH)4
15.11Allophane(Al2O3)(SiO2)1.3-2 · 2.5-3H2O

Other Names for Andalusite

Name in Other Languages:
Bosnian (Latin Script):Andaluzit
Croatian:Andaluzit
Esperanto:Andaluzito
Estonian:Andalusiit
Galician:Andalucita
Hungarian:Andalúzit
Italian:Andalusite
Japanese:紅柱石
Lithuanian:Andalūzitas
Polish:Andaluzyt
Portuguese:Andaluzita
Romanian:Andaluzit
Serbian (Cyrillic Script):Андалузит
Simplified Chinese:红柱石
Swedish:Andalusit

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 Andalusite

Reference List:
Delamétherie, J. C. (1798): Sur une pierre de l´andalousie. Journal de Physique, de Chimie et d´Histoire Naturelle. 46, 386-387

Peck, A.B. (1924) Note on andalusite from California; a new use and some thermal properties. American Mineralogist: 9: 123-129.

Pearson, G.R. and Shaw, D.M. (1960) Trace elements in kyanite, sillimanite and andalusite. American Mineralogist: 45: 808-817.

Burnham, C.W. and Buerger, M.J. (1961) Refinement of the crystal structure of andalusite. Zeitschrift für Kristallographie: 115: 269-290.

Sgarlata F. (1962) Sulla struttura cristallina dell'andalusite. Periodico di Mineralogia – Roma pp. 43-61.

Chinner, G.A., J.W. Smith & C.R. Knowles (1969), Transition metal contents of Al2SiO5 polymorphs: American Journal of Science: 267A: 96-113.

G. H. Faye and D. C. Harris (1969): On the origin of colour and pleochroism in andalusite from Brazil. Can. Mineral. 10, 47-56.

Hafner, S.S., Raymond, M., and Ghose, S. (1970) Nuclear quadrupole coupling tensors of Al27 in andalusite (Al2SiO5). Journal of Chemical Physics: 52: 6037-6041.

Finger, L.W. and Prince, E. (1972) Neutron diffraction studies: andalusite and sillimanite. Carnegie Institution of Washington, Year Book: 71: 496-500.

Vaughan, M.T. and Weidner, D.J. (1978) The relationship of elasticity and crystal structure in andalusite and sillimanite. Physics and Chemistry of Minerals: 3: 133-144.

Winter, J.K. and Ghose, S. (1979) Thermal expansion and high-temperature crystal chemistry of the Al2SiO5 polymorphs. American Mineralogist: 64: 573-586.

Ralph, R.L., Finger, L.W., Hazen, R.M., and Ghose, S. (1984) Compressibility and crystal structure of andalusite at high pressure. American Mineralogist: 69: 513-519.

Vernon, R.H., Flood, R.H., and D'Arcy, W.F. (1987) Sillimanite and andalusite produced by base-cation leaching and contact metamorphism of felsic igneous rocks. Journal of Metamorphic Geology: 5: 439-450.

Kerrick, D.M. (1990) Metamorphic reactions. In D.M. Kerrick, Ed., The Al2SiO5 polymorphs. 22, 223-253. Reviews in Mineralogy. Mineralogical Society of America, Chantilly, Virginia.

Kerrick, D.M. (1990) The Al2SiO5 polymorphs, 22, 406 p. Reviews in Mineralogy, Mineralogical Society of America, Chantilly, Virginia.

Bryant, P.L., Harwell, C.R., Wu, K., Fronczek, F.R., Hall, R.W., and Butler, L.G. (1999) Single-crystal 27 Al NMR of andalusite and calculated electric field gradients: the first complete NMR assignment for a 5-coordinated aluminum site. Journal of Physical Chemistry A, 103: 5246-5252.

Dahaoui, S., Ghermani, N.E., Ghose, S., and Howard, J.A.K. (2001) Electric field gradient tensors at the aluminum sites in the Al2SiO5 polymorphs from CCD high resolution X-ray diffraction data: comparison with 27 Al NMR results. American Mineralogist: 86: 159-164.

Iglesias, M., Schwarz, K., Blaha, P., and Baldomir, D. (2001) Electronic structure and electric field gradient calculations of Al2SiO5 polymorphs. Physics and Chemistry of Minerals: 28: 67-75.

Winkler, B., Hytha, M., Warren, M.C., Milman, V., Gale, J.D., and Schreuer, J. (2001) Calculation of the elastic constants of the Al2SiO5 olymorphs andalusite, sillimanite, and kyanite. Zeitschrift für Kristallographie: 216: 67-70.

Burt, J.B., Ross, N.L., Angel, R.J., and Koch, M. (2006) Equations of state and structures of andalusite to 9.8 GPa and sillimanite to 8.5 GPa. American Mineralogist: 91: 319-326.

Ohuchi, F.S., Ghose, S., Engelhard, M.H., and Baer, D.R. (2006) Chemical bonding and electronic structures of the Al2SiO5 polymorphs, andalusite, sillimanite, and kyanite: X-ray photoelectron- and electron energy loss spectroscopy studies. American Mineralogist: 91: 740-746.

Internet Links for Andalusite

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

Localities for Andalusite

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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