Boromullite Mineral Data

General Boromullite Information

Chemical Formula:

Al4.5SiB0.5O9.5

Composition:

Molecular Weight = 610.43 gm

Magnesium 0.04 % Mg 0.07 % MgO

Aluminum 39.25 % Al 74.16 % Al₂O₃

Iron 0.27 % Fe 0.35 % FeO

Silicon 8.88 % Si 19.00 % SiO₂

Boron 2.02 % B 6.50 % B₂O₃

Oxygen 49.54 % O

______ ______

100.00 % 100.08 % = TOTAL OXIDE

Empirical Formula:

Mg_0.01Fe²⁺_0.03Al_8.88Si_1.93B_1.14O_18.9

Environment:

Formed during anatexis of B-rich pelitic rocks under granulite facies conditions. Structurally related to mullite.

IMA Status:

Approved IMA 2007 (Dana # Added)

Locality:

Mount Stafford, Northern Territory, Australia Link to MinDat.org Location Data.

Name Origin:

Named as the boron analog to mullite.

Synonym:

IMA2007-021

Boromullite Image

Images:

Boromullite

Comments: PPL image of holotype boromullite prism in thin section 2006-MST22a. Bmu = boromullite, Crd = cordierite, Hc = hercynite, Kfs = K-feldspar, Sil = sillimanite. Eur. J. Mineral v20:935.
Location: Mount Stafford, central Australia. Scale: See Image.
© Eur. J. Mineral

Images:

Boromullite

Comments: BSE image of holotype boromullite prism in thin section 2006-MST22a. Bmu = boromullite, Crd = cordierite, Hc = hercynite, Kfs = K-feldspar, Sil = sillimanite. Eur. J. Mineral v20:935.
Location: Mount Stafford, central Australia. Scale: See Image.
© Eur. J. Mineral

Boromullite Crystallography

Axial Ratios:

a:b:c =0.3805:1:0.5108

Cell Dimensions:

a = 5.7168, b = 15.023, c = 7.675, Z = 2; V = 659.16 Den(Calc)= 3.08

Crystal System:

Orthorhombic - PyramidalH-M Symbol (mm2) Space Group: C mc2₁

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

By Intensity(I/I_o): 3.38(1), 1.512(0.8), 2.19(0.8),2.51(0.6), 2.67(0.6), 2.11(0.5), 5.37(0.5), 1.682(0.3),

Crystal Structure:

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Buick I S , Grew E S , Armbruster T , Medenbach O , Yates M , Bebout G , Clarke G , European Journal of Mineralogy , 20 (2008) p.935-950, Boromullite, Al9BSi2O19, a new mineral from granulite-facies metapelites, Mount, Safford, central Australia: a natural analogue of a synthetic boron-mullite , Locality: Mount Safford, central Australia

Physical Properties of Boromullite

Cleavage:

None

Color:

White.

Diaphaneity:

Transparent

Habit:

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

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Boromullite

Gladstone-Dale:

CI calc= 0.005 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2067,KC= 0.2078
Ncalc = 1.64

Optical Data:

Biaxial (+), a=1.627, b=1.634, g=1.649, bire=0.0220

Calculated Properties of Boromullite

Electron Density:

Bulk Density (Electron Density)=3.03 gm/cc
note: Specific Gravity of Boromullite =3.08 gm/cc.

Fermion Index:

Fermion Index = 0.008500053
Boson Index = 0.991499947

Photoelectric:

PE_Boromullite= 1.59 barns/electron
U=PE_Boromullite x rElectron Density= 4.82 barns/cc.

Radioactivity:

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

Boromullite Classification

Dana Class:

52.02.02a.03 (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.23 09 - SILICATES (Germanates)

09.A - Nesosilicates

09.AF -Nesosilicates with additional anions;

09.AF.23 Boromullite! Al4.5SiB0.5O9.5 C mc2₁ mm2

Other Boromullite Information

References:

NAME( AmMin, v94:648) PHYS. PROP.(AmMin, v94:648) OPTIC PROP.(AmMin, v94:648)

See Also:

Links to other databases for Boromullite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - MinDAT
7 - Mineralienatlas (Deutsch)
8 - Online Mineral Museum
9 - QUT Mineral Atlas
10 - Ruff.Info

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Ask about Boromullite here :
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Print or Cut-and-Paste your Boromullite Specimen Label here :

Boromullite

Al4.5SiB0.5O9.5
Dana No: 52.02.02a.03 Strunz No: 09.AF.23
Locality:

Notes: