Mullite Mineral Data

General Mullite Information

Chemical Formula:

Al(4+2x)Si(2-2x)O(10-x) where x =0.17 to 0.59

Composition:

Molecular Weight = 319.54 gm

Aluminum 38.00 % Al 71.79 % Al₂O₃

Silicon 13.18 % Si 28.21 % SiO₂

Oxygen 48.82 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Al_4.5Si_1.5O_9.75

Environment:

Remelted Tertiary-aged clays.

IMA Status:

Valid Species (Pre-IMA) 1924

Locality:

Isle of Mull, Scotland, England. Link to MinDat.org Location Data.

Name Origin:

Named after its locality.

Name Pronunciation:

Mullite

Mullite Image

Images:

Mullite

Comments: Opaque white mullite masses with mica.
Location: Nijar, Almeria, Andalucia, Spain. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Images:

Mullite

Comments: Surface of a kaolinite stratum altered to white mullite by a prehistoric coal-seam-fire..
Location: Mt. Wingen (Burning Mountain), NSW, Australia. Scale: Picture size 6x4 cm.
© Dave Barthelmy

Mullite Crystallography

Axial Ratios:

a:b:c =0.9865:1:0.3757

Cell Dimensions:

a = 7.5785, b = 7.6817, c = 2.8864, Z = 1; V = 168.03 Den(Calc)= 3.16

Crystal System:

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

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

By Intensity(I/I_o): 3.39(1), 3.428(0.95), 2.206(0.6),

Crystal Structure:

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Angel R J , Prewitt C T , American Mineralogist , 71 (1986) p.1476-1482, Crystal structure of mullite: A re-examination of the average structure

View Additional jPOWD Structure files for Mullite
[1] [10] [11] [2] [3] [4] [5] [6] [7] [8] [9]

Physical Properties of Mullite

Cleavage:

{010} Good

Color:

Colorless, Violet, Yellow, White, Light pink.

Density:

3 - 3.1, Average = 3.05

Diaphaneity:

Transparent to translucent

Fracture:

Brittle - Generally displayed by glasses and most non-metallic minerals.

Habit:

Crystalline - Fine - Occurs as well-formed fine sized crystals.

Habit:

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

Hardness:

6-7 - Orthoclase-Quartz

Luminescence:

Non-fluorescent.

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Mullite

Gladstone-Dale:

CI meas= -0.035 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= 0.001 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2071,KPDmeas= 0.2146,KC= 0.2073
Ncalc = 1.62 - 1.66

Optical Data:

Biaxial (+), a=1.642-1.653, b=1.644-1.655, g=1.654-1.679, bire=0.0120-0.0260, 2V(Calc)=34-50, 2V(Meas)=20-50. Dispersion r > v.

Pleochroism (x):

colorless or colorless.

Pleochroism (y):

colorless or colorless.

Calculated Properties of Mullite

Electron Density:

Bulk Density (Electron Density)=3.12 gm/cc
note: Specific Gravity of Mullite =3.16 gm/cc.

Fermion Index:

Fermion Index = 0.0063912836
Boson Index = 0.9936087164

Photoelectric:

PE_Mullite= 1.62 barns/electron
U=PE_Mullite x rElectron Density= 5.04 barns/cc.

Radioactivity:

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

Mullite Classification

Dana Class:

52.02.02a.02 (52)Nesosilicate Insular SiO4 Groups and O, OH, F, and H2O

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

(52.02.02a)Al2SiO5 (Sillimanite subgroup)

52.02.02a.01 Sillimanite Al2SiO5=Al[6]Al[4]OSiO4 P nma 2/m 2/m 2/m

52.02.02a.02 Mullite Al(42x)Si(2-2x)O(10-x)wherex=0.17to0.59 Pbam 2/m 2/m 2/m

52.02.02a.03 Boromullite! Al4.5SiB0.5O9.5 C mc2₁ mm2

Strunz Class:

09.AF.20 09 - SILICATES (Germanates)

09.A - Nesosilicates

09.AF -Nesosilicates with additional anions;

09.AF.20 Mullite Al(42x)Si(2-2x)O(10-x)wherex=0.17to0.59 Pbam 2/m 2/m 2/m

Other Mullite Information

See Also:

Links to other databases for Mullite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info
15 - WWW-MINCRYST

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Ask about Mullite here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Español

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

Mullite

Al(4+2x)Si(2-2x)O(10-x) where x =0.17 to 0.59
Dana No: 52.02.02a.02 Strunz No: 09.AF.20
Locality:

Notes: