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Sillimanite Mineral Data

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General Sillimanite Information

Help on Chemical  Formula: Chemical Formula: Al2SiO5 = Al[6]Al[4]OSiO4
Help on Composition: 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
Help on Empirical Formula: Empirical Formula: (Al2O3)(SiO2)
Help on Environment: Environment: Metamorphosed peri-aluminous sedimentary rocks.
Help on IMA Status: IMA Status: Valid Species (Pre-IMA) 1824
Help on Locality: Locality: Wide spread world wide occurrences. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named after the American chemist and mineralogist, B. Silliman (1779-1824).
Help on Name Pronunciation: Name Pronunciation: Sillimanite + Pronunciation Say SILLIMANITE
Help on Synonym: Synonym: Fibrolite
  ICSD 100450
  PDF 38-471

Sillimanite Image

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Comments: Silky massive sillimanite.
Location: Khasia Hills, Assum, India. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Sillimanite Crystallography

Help on Axial Ratios: Axial Ratios: a:b:c =0.9754:1:0.752
Help on Cell Dimensions: Cell Dimensions: a = 7.484, b = 7.672, c = 5.77, Z = 4; V = 331.30 Den(Calc)= 3.25
Help on Crystal System: Crystal System: Orthorhombic - Dipyramidal H-M Symbol (2/m 2/m 2/m) Space Group: P nma
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 3.42(1), 3.37(0.65), 2.2(0.6),
Help on Forms: Forms:

Dbl Clk - Start-Stop Rotation
RMB - Cycle Display Modes
Drag1 - Manipulate Crystal
Drag2 - Resize

S - Stereo
I - Indicies
<space> - Start-Stop Rotation
F - Fit to Screen
M - Menu

Help on Above

Forms: ( 1 2 0) ( 2 1 0) ( 1 1 0) ( 1 0 0) ( 0 0 1)

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Physical Properties of Sillimanite

Help on Cleavage: Cleavage: {010} Perfect
Help on Color: Color: Bluish, Brownish greenish, Colorless, Gray, Gray green.
Help on Density: Density: 3.24
Help on Diaphaneity: Diaphaneity: Transparent to translucent
Help on Fracture: Fracture: Splintery - Thin, elongated fractures produced by intersecting good cleavages or partings (e.g. hornblende).
Help on Habit: Habit: Acicular - Occurs as needle-like crystals.
Help on Habit: Habit: Fibrous - Crystals made up of fibers.
Help on Habit: Habit: Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).
Help on Hardness: Hardness: 7 - Quartz
Help on Luminescence: Luminescence: Non-fluorescent.
Help on Luster: Luster: Vitreous (Glassy)
Help on Streak: Streak: white

Optical Properties of Sillimanite

Help on Gladstone-Dale: Gladstone-Dale: CI meas= 0.01 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.013 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2047,KPDmeas= 0.2053,KC= 0.2074
Ncalc = 1.67
Help on Optical Data: Optical Data: Biaxial (+), a=1.653-1.661, b=1.654-1.67, g=1.669-1.684, bire=0.0160-0.0230, 2V(Calc)=30-80, 2V(Meas)=20-30. Dispersion strong, r > v.
Help on Pleochroism (x): Pleochroism (x): colorless, pale brown, or yellow.
Help on Pleochroism (y): Pleochroism (y): colorless, brown, or grayish green.

Calculated Properties of Sillimanite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=3.20 gm/cc
note: Specific Gravity of Sillimanite =3.24 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.0083309363
Boson Index = 0.9916690637
Help on Photoelectric: Photoelectric: PESillimanite = 1.64 barns/electron
U=PESillimanite x rElectron Density= 5.24 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Sillimanite is Not Radioactive

Sillimanite Classification

Help on  Dana Class: Dana Class: 52.02.02a.01 (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
Help on  Strunz Class: Strunz Class: 09.AF.05 09 - SILICATES (Germanates)
  09.A - Nesosilicates
  09.AF -Nesosilicates with additional anions;
09.AF.05 Sillimanite Al2SiO5=Al[6]Al[4]OSiO4 P nma 2/m 2/m 2/m

Other Sillimanite Information

Help on See Also: See Also: Links to other databases for Sillimanite :
1 - Am. Min. Crystal Structure Database
2 - Amethyst Galleries' Mineral Gallery
3 - Athena
4 - CalTech Mineral Spectroscopy
5 - EUROmin Project
6 - Ecole des Mines de Paris
7 - Franklin Minerals(Dunn)
8 - GeoScienceWorld
9 - Google Images
10 - Google Scholar
11 - Handbook of Mineralogy (MinSocAm)
12 - Handbook of Mineralogy (UofA)
13 - HyperPhysics
14 - MinDAT
15 - Mineralienatlas (Deutsch)
16 - Minerals in Thin Sections-Humboldt State
17 - Online Mineral Museum
18 - QUT Mineral Atlas
19 - Ruff.Info
20 - Scandinavian mineral gallery
21 - UCLA - Petrography Thin-Sections
22 - University of Colorado - Mineral Structure Data
24 - YupRocks

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


Al2SiO5 = Al[6]Al[4]OSiO4
Dana No: 52.02.02a.01 Strunz No: 09.AF.05





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