Andalusite Mineral Data

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.

Name Pronunciation:

Andalusite + Pronunciation

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 - Dipyramidal H-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),

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

Diaphaneity:

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:

Non-fluorescent.

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
Ncalc = 1.65 - 1.66

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.

Calculated Properties of Andalusite

Electron Density:

Bulk Density (Electron Density)=3.11 gm/cc
note: Specific Gravity of Andalusite =3.15 gm/cc.

Fermion Index:

Fermion Index = 0.0083309363
Boson Index = 0.9916690637

Photoelectric:

PE_Andalusite= 1.64 barns/electron
U=PE_Andalusite x rElectron Density= 5.10 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Andalusite is Not Radioactive

Andalusite Classification

Dana Class:

52.02.02b.01 (52)Nesosilicate Insular SiO4 Groups and O, OH, F, and H2O

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

(52.02.02b)AL2SIO5 Andalusite subgroup)

52.02.02b.01 Andalusite Al2SiO5=Al[6]Al[5]OSiO4 Pnnm 2/m 2/m 2/m

52.02.02b.02 Kanonaite (Mn,Al)AlSiO5 Pnnm 2/m 2/m 2/m

52.02.02b.03 Yoderite Mg2(Al,Fe)6Si4O18(OH)2 P 2₁ 2

Strunz Class:

09.AF.10 09 - SILICATES (Germanates)

09.A - Nesosilicates

09.AF -Nesosilicates with additional anions;

09.AF.10 Andalusite Al2SiO5=Al[6]Al[5]OSiO4 Pnnm 2/m 2/m 2/m

09.AF.10 Kanonaite (Mn,Al)AlSiO5 Pnnm 2/m 2/m 2/m

Other Andalusite Information

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Andalusite

Al2SiO5 = Al[6]Al[5]OSiO4
Dana No: 52.02.02b.01 Strunz No: 09.AF.10
Locality:

Notes:

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