Andalusite Mineral Data

Andalusite Mineral Data +

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General Andalusite Information

Chemical Formula:

Al2SiO5 = Al[6]Al[5]OSiO4

Composition:

Molecular Weight = 162.05 gm

Aluminum 33.30 % Al 62.92 % Al₂O₃

Silicon 17.33 % Si 37.08 % SiO₂

Oxygen 49.37 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Al₂SiO₅

Environment:

Metamorphosed peri-aluminous sedimentary rocks.

IMA Status:

Valid Species (Pre-IMA) 1789

Locality:

Andalucia (Spain), an early but now unimportant location. Link to MinDat.org Location Data.

Name Origin:

Named after its locality.

Synonym:

Chiastolite

ICSD 24275

PDF 39-376

Andalusite Image

Images:

Andalusite

Comments: Wine colored andalusite associated with mica.
Location: Sierra Albarrana, Cordoba, Spain. Scale: 4.5 x 3.5 cm.
© Fabre Minerals

Andalusite Crystallography

Axial Ratios:

a:b:c =0.986:1:0.7037

Cell Dimensions:

a = 7.79, b = 7.9, c = 5.56, Z = 4; V = 342.17 Den(Calc)= 3.15

Crystal System:

Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: Pnnm

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 5.54(1), 2.77(0.9), 4.53(0.9),

Crystal Structure:

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Winter J K , Ghose S , American Mineralogist , 64 (1979) p.573-586, Thermal expansion and high-temperature crystal chemistry of the Al2SiO5, polymorphs, T = 25 deg C

View Additional jPOWD Structure files for Andalusite
[1] [10] [11] [12] [13] [14] [15] [16] [2] [3] [4] [5] [6] [7] [8] [9]

Physical Properties of Andalusite

Cleavage:

[110] Distinct, [100] Indistinct, [010] Poor

Color:

Dark green, Gray, Brown, Red, Green.

Density:

3.13 - 3.17, Average = 3.15

Diaphaniety:

Transparent to translucent

Fracture:

Splintery - Thin, elongated fractures produced by intersecting good cleavages or partings (e.g. hornblende).

Habit:

Blocky - Crystal shape tends to be equant (e.g. feldspars).

Habit:

Euhedral Crystals - Occurs as well-formed crystals showing good external form.

Habit:

Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).

Hardness:

6.5-7 - Pyrite-Quartz

Luminescence:

None.

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Andalusite

Gladstone-Dale:

CI meas= 0.022 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= 0.022 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2029,KPDmeas= 0.2029,KC= 0.2074

Optical Data:

Biaxial (-), a=1.629-1.64, b=1.633-1.644, g=1.638-1.65, bire=0.0090-0.0100, 2V(Calc)=80-84, 2V(Meas)=48-68. Dispersion r > v.

Pleochroism (x):

pink, light red, or yellow.

Pleochroism (y):

colorless, pale yellow, or green.

Pleochroism (z):

colorless, pale yellow, or greenish yellow.

Calculated Properties of Andalusite

Electron Density:

r_electron=3.11 gm/cc
note: r_Andalusite=3.15 gm/cc.

Fermion Index

Fermion Index = 0.00833
Boson Index = 0.99167

Photoelectric:

PE_Andalusite= 1.64 barns/electron
U=PE_Andalusite x r_electron= 5.10 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Andalusite is Not Radioactive

Andalusite Classification

Dana Class:

52.2.2b.1 (52)Nesosilicate Insular SiO4 Groups and O, OH, F, and H2O

(52.2)with cations in [4] and >[4] coordination

(52.2.2b)AL2SIO5 Andalusite subgroup)

52.2.2b.1 Andalusite Al2SiO5=Al[6]Al[5]OSiO4 Pnnm 2/m 2/m 2/m

52.2.2b.2 Kanonaite (Mn,Al)AlSiO5 Pnnm 2/m 2/m 2/m

52.2.2b.3 Yoderite Mg2(Al,Fe)6Si4O18(OH)2 P 2₁ 2

Strunz Class:

VIII/B.02-20 VIII - Silicates

VIII/B - Nesosubsilicates, with anions unfamiliar to tetraheders, cations of octahedral and tetrahedral orientation [4/6]

VIII/B.02 - Disthene series

VIII/B.02-10 Sillimanite Al2SiO5=Al[6]Al[4]OSiO4 P nma 2/m 2/m 2/m

VIII/B.02-20 Andalusite Al2SiO5=Al[6]Al[5]OSiO4 Pnnm 2/m 2/m 2/m

VIII/B.02-30 Kanonaite (Mn,Al)AlSiO5 Pnnm 2/m 2/m 2/m

VIII/B.02-40 Kyanite Al2SiO5=Al[6]Al[6]OSiO4 P1 1

VIII/B.02-50 Mullite Al(42x)Si(2-2x)O(10-x)wherex=0.17to0.59 Pbam 2/m 2/m 2/m

VIII/B.02-60 Yoderite Mg2(Al,Fe)6Si4O18(OH)2 P 2₁ 2

VIII/B.02-70 Topaz Al2SiO4(F,OH)2 Pbnm 2/m 2/m 2/m

Other Andalusite Information

References:

NAME( ODonoghue90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Heinrich65)

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Print or Cut-and-Paste your Andalusite Specimen Label here :

Andalusite

Al2SiO5 = Al[6]Al[5]OSiO4
Dana No: 52.2.2b.1 Strunz No: VIII/B.02-20
Locality:

Notes: