Dumortierite Mineral Data

Dumortierite Mineral Data +

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General Dumortierite Information

Chemical Formula:

Al6.5-7(BO3)(SiO4)3(O,OH)3

Composition:

Molecular Weight = 569.73 gm

Aluminum 32.68 % Al 61.74 % Al₂O₃

Silicon 14.79 % Si 31.64 % SiO₂

Boron 1.90 % B 6.11 % B₂O₃

Hydrogen 0.09 % H 0.79 % H₂O

Oxygen 50.55 % O

______ ______

100.00 % 100.28 % = TOTAL OXIDE

Empirical Formula:

Al_6.9(BO₃)(SiO₄)₃O_2.5(OH)_0.5

Environment:

Pegmatites, pneumatolytic, and metamorphic rocks.

IMA Status:

Valid Species (Pre-IMA) 1881

Locality:

San Diego Co., California. Link to MinDat.org Location Data.

Name Origin:

Named after the French paleontologist, M. E. Dumortier (1803-1873).

Synonym:

ICSD 100443

PDF Jul-71

Dumortierite Image

Images:

Dumortierite

Comments: Blue dumortierite in matrix.
Location: Hartmannsdorf, Chemnitz, Saxony, Germany. Scale: Picture size 5 mm.
© Thomas Witzke / Abraxas-Verlag

Images:

Dumortierite

Comments: Divergent fans of acicular purple to lilac colored dumortierite crystals in white andalusite matrix.
Location: Dehesa, San Diego Co., California, USA. Scale: Crystal size 2.3cm.
© Tom Loomis / Dakota Matrix

Images:

Dumortierite

Comments: Low-magnification, bright-field image showing dispersed dumortierite fibers extracted from rose quartz on a carbon film. (AmMin 87:270).
Location: Madagascar. Scale: See Image.
© American Mineralogist

Dumortierite Crystallography

Axial Ratios:

a:b:c =0.5827:1:0.2338

Cell Dimensions:

a = 11.76, b = 20.18, c = 4.72, Z = 4; V = 1,120.14 Den(Calc)= 3.38

Crystal System:

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

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

By Intensity(I/I_o): 2.549(1), 5.09(0.9), 5.89(0.9),

Forms:

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Forms: [ 1 0 0] [ 0 0 1] [ 1 1 0] [ 1 3 0] [ 0 1 0]

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Crystal Structure:

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Alexander V D , Griffen D T , Martin T J , American Mineralogist , 71 (1986) p.786-794, Crystal chemistry of some Fe- and Ti-poor dumortierites, Sample: #2, BYU 12-5027, from Yuma Co., Arizona, USA

View Additional jPOWD Structure files for Dumortierite
[1] [2] [3] [4] [5]

Physical Properties of Dumortierite

Cleavage:

[100] Good, [110] Indistinct

Color:

Blue, Brown, Violet, Greenish blue, Pink.

Density:

3.3 - 3.4, Average = 3.34

Diaphaniety:

Transparent to translucent

Fracture:

Fibrous - Thin, elongated fractures produced by crystal forms or intersecting cleavages (e.g. asbestos).

Habit:

Columnar - Forms columns

Habit:

Fibrous - Crystals made up of fibers.

Habit:

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

Hardness:

8.5 - Chrysoberyl

Luminescence:

None.

Luster:

Vitreous (Glassy)

Magnetism:

Nonmagnetic

Streak:

white

Optical Properties of Dumortierite

Gladstone-Dale:

CI meas= 0.028 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= 0.037 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2017,KPDmeas= 0.2035,KC= 0.2094

Optical Data:

Biaxial (-), a=1.659-1.678, b=1.684-1.691, g=1.686-1.692, bire=0.0140-0.0270, 2V(Calc)=30, 2V(Meas)=20-52. Dispersion r > v or r < v.

Pleochroism (x):

blue, violet, greenish blue, or deep rose.

Pleochroism (y):

colorless, reddish violet, pale lilac blue, or yellow.

Pleochroism (z):

colorless, pale blue, pale green, or red.

Calculated Properties of Dumortierite

Electron Density:

r_electron=3.31 gm/cc
note: r_Dumortierite=3.35 gm/cc.

Fermion Index

Fermion Index = 0.01092
Boson Index = 0.98908

Photoelectric:

PE_Dumortierite= 1.55 barns/electron
U=PE_Dumortierite x r_electron= 5.11 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Dumortierite is Not Radioactive

Dumortierite Classification

Dana Class:

54.1.2.1 (54)Nesosilicate Borosilicates and Some Beryllosilicates

(54.1)with (BO3)

(54.1.2)Dumortierite group

54.1.2.1 Dumortierite Al6.5-7(BO3)(SiO4)3(O,OH)3 Pcmn 2/m 2/m 2/m

54.1.2.2 Magnesiodumortierite (Mg,Ti,[])<1(Al,Mg)2Al4Si3O18-y(OH)yBy=2-3 Pmcn 2/m 2/m 2/m

Strunz Class:

VIII/B.31-20 VIII - Silicates

VIII/B - Nesosubsilicates, with anions unfamiliar to tetraheders, with beryllium and boron

VIII/B.31 - Kornerupine - Harkerite series

VIII/B.31-10 Kornerupine (Mg,Fe)4(Al,Fe)6(SiO4,BO4)5(O,OH)2 C mcm 2/m 2/m 2/m

VIII/B.31-12 Prismatine! ([],Fe,Mg)(Mg,Al,Fe)5Al4Si2(Si,Al)2(B,Si,Al)(O,OH,F)22 C mcm 2/m 2/m 2/m

VIII/B.31-15 Magnesiodumortierite (Mg,Ti,[])<1(Al,Mg)2Al4Si3O18-y(OH)yBy=2-3 Pmcn 2/m 2/m 2/m

VIII/B.31-20 Dumortierite Al6.5-7(BO3)(SiO4)3(O,OH)3 Pcmn 2/m 2/m 2/m

VIII/B.31-30 Holtite Al6(Al,Ta)(BO3)[(SiO4,SbO4,AsO4)]3(O,OH)3 P nma 2/m 2/m 2/m

VIII/B.31-40 Grandidierite (Mg,Fe)Al3(BO4)(SiO4)O Pbnm 2/m 2/m 2/m

VIII/B.31-42 Ominelite! (Fe,Mg)Al3BSiO9 Pbnm 2/m 2/m 2/m

VIII/B.31-45 Boralsilite! Al16B6Si2O27 C 2/m 2/m

VIII/B.31-50 Werdingite (Mg,Fe)2Al14B4Si4O37 P1 1

VIII/B.31-60 Harkerite Ca24Mg8Al2(SiO4)8(BO3)6(CO3)10·2(H2O) R 3m 3 2/m

Other Dumortierite Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Heinrich65)

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Dumortierite

Al6.5-7(BO3)(SiO4)3(O,OH)3
Dana No: 54.1.2.1 Strunz No: VIII/B.31-20
Locality:

Notes: