Cordierite Mineral Data

Cordierite Mineral Data +

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General Cordierite Information

Chemical Formula:

Mg2Al4Si5O18

Composition:

Molecular Weight = 584.95 gm

Magnesium 8.31 % Mg 13.78 % MgO

Aluminum 18.45 % Al 34.86 % Al₂O₃

Silicon 24.01 % Si 51.36 % SiO₂

Oxygen 49.23 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Mg₂Al₄Si₅O₁₈

Environment:

Magmatic, metamorphic, and pegmatitic rocks.

IMA Status:

Valid Species (Pre-IMA) 1813

Locality:

Bodenmais, Germany. Link to MinDat.org Location Data.

Name Origin:

From the French mining engineer and geologist P. L. A. Cordier (1777-1861).

Synonym:

Dichroite

ICSD 100250

Iolite

PDF 12-303

Cordierite Image

Images:

Cordierite

Comments: Brown rectangular cordierite crystals in matrix. These crystals are not gemmy enough to be called iolite.
Location: Richmond Soapstone Quarry, Richmond, Cheshire Co., New Hampshire, USA. Scale: 24x20x15 mm.
© John Betts - Fine Minerals

Cordierite Crystallography

Axial Ratios:

a:b:c =1.7479:1:0.954

Cell Dimensions:

a = 17.13, b = 9.8, c = 9.35, Z = 4; V = 1,569.62 Den(Calc)= 2.48

Crystal System:

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

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

By Intensity(I/I_o): 3.13(1), 8.45(0.8), 8.54(0.8),

Crystal Structure:

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Gibbs G V , American Mineralogist , 51 (1966) p.1068-1087, The polymorphism of cordierite I: The crystal structure of low cordierite

View Additional jPOWD Structure files for Cordierite
[1] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [2] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [3] [30] [31] [32] [33] [34] [35] [36] [37] [38] [39] [4] [40] [41] [42] [43] [44] [45] [46] [47] [5] [6] [7] [8] [9]

Physical Properties of Cordierite

Cleavage:

[010] Poor

Color:

Colorless, Pale blue, Violet, Yellow, Gray.

Density:

2.55 - 2.75, Average = 2.65

Diaphaniety:

Transparent to translucent

Fracture:

Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).

Habit:

Massive - Granular - Common texture observed in granite and other igneous rock.

Habit:

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

Hardness:

7 - Quartz

Luminescence:

None.

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Cordierite

Gladstone-Dale:

CI meas= -0.008 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.077 (Fair) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2224,KPDmeas= 0.2081,KC= 0.2065

Optical Data:

Biaxial (-), a=1.527-1.56, b=1.532-1.574, g=1.538-1.578, bire=0.0110-0.0180, 2V(Calc)=54-86, 2V(Meas)=75-89. Dispersion weak, r < v.

Pleochroism (x):

colorless, pale yellow, or pale yellow.

Pleochroism (y):

colorless, violet, or blue.

Pleochroism (z):

colorless, blue, or blue.

Calculated Properties of Cordierite

Electron Density:

r_electron=2.63 gm/cc
note: r_Cordierite=2.65 gm/cc.

Fermion Index

Fermion Index = 0.01975
Boson Index = 0.98025

Photoelectric:

PE_Cordierite= 1.65 barns/electron
U=PE_Cordierite x r_electron= 4.32 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Cordierite is Not Radioactive

Cordierite Classification

Dana Class:

61.2.1.1 (61)Cyclosilicate Six-Membered Rings

(61.2)with Al substituted rings

(61.2.1)Cordierite group

61.2.1.1 Cordierite Mg2Al4Si5O18 C ccm 2/m 2/m 2/m

61.2.1.2 Sekaninaite (Fe,Mg)2Al4Si5O18 C ccm 2/m 2/m 2/m

Strunz Class:

VIII/E.12-40 VIII - Silicates

VIII/E - Cyklosilicates, six rings [Si6O18]12-

VIII/E.12 - Beryl series

VIII/E.12-10 Beryl Be3Al2Si6O18 P 6/mmc 6/m 2/m 2/m

VIII/E.12-20 Bazzite Be3(Sc,Al)2Si6O18 P 6/mcc 6/m 2/m 2/m

VIII/E.12-25 Stoppaniite! (Fe,Al,Mg)4(Na,[])2[Be6Si12O36]·2(H2O) P 6/mmc 6/m 2/m 2/m

VIII/E.12-30 Indialite Mg2Al4Si5O18 P 6/mcc 6/m 2/m 2/m

VIII/E.12-40 Cordierite Mg2Al4Si5O18 C ccm 2/m 2/m 2/m

VIII/E.12-50 Sekaninaite (Fe,Mg)2Al4Si5O18 C ccm 2/m 2/m 2/m

Other Cordierite Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Mason68)

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Cordierite

Mg2Al4Si5O18
Dana No: 61.2.1.1 Strunz No: VIII/E.12-40
Locality:

Notes: