Boralsilite Mineral Data

General Boralsilite Information

Chemical Formula:

Al16B6Si2O27

Composition:

Molecular Weight = 1,144.71 gm

Aluminum 37.71 % Al 71.26 % Al₂O₃

Silicon 4.91 % Si 10.50 % SiO₂

Boron 5.67 % B 18.25 % B₂O₃

Oxygen 51.71 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Al₁₆B₆Si₂O₃₇

Environment:

Found in a tourmaline - quartz intergrowth in granitic pegmatite cutting granulite-facies metapelitic rocks, Structurally related to sillimanite.

IMA Status:

Approved IMA 1998 (Dana # Added)

Locality:

Stornes Peninsula, Larsemann Hills, Prydz Bay, east Antarctica. Almgjotheii in the aureole of the Rogaland intrusive complex, southwestern Norway. Link to MinDat.org Location Data.

Name Origin:

Named after its composition of (bor}on, (al)uminum, and (sil)icon.

Name Pronunciation:

Boralsilite + Pronunciation

Synonym:

ICSD 87662

IMA1996-029

PDF 51-1451

Boralsilite Image

Images:

Boralsilite Grandidierite

Comments: B&W PPL image of aggregates of boralsilite in quartz near grandidierite. Pyrite is partially replaced by oxide. Abbrev: A+B = Secondary andalusite, B = boralsilite, G = grandidierite, P = pyrite, Q = quartz. (AmMin v93:294).
Location: Pegmatites from the Larsemann Hills, East Antarctica. Scale: See Image.
© American Mineralogist

Boralsilite Crystallography

Axial Ratios:

a:b:c =2.6492:1:2.7052

Cell Dimensions:

a = 14.767, b = 5.574, c = 15.079, Z = 2; beta = 91.96° V = 1,240.45 Den(Calc)= 3.06

Crystal System:

Monoclinic - Prismatic H-M Symbol (2/m) Space Group: C 2/m

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

By Intensity(I/I_o): 5.19(1), 4.31(0.7), 5.41(0.7),

Physical Properties of Boralsilite

Cleavage:

{???} Fair, {???} Fair

Color:

White, Colorless.

Density:

3.06

Diaphaneity:

Transparent

Habit:

Aggregates - Made of numerous individual crystals or clusters.

Habit:

Fibrous - Crystals made up of fibers.

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Boralsilite

Gladstone-Dale:

CI meas= -0.004 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.004 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2095,KPDmeas= 0.2095,KC= 0.2086
Ncalc = 1.64

Optical Data:

Biaxial (+), a=1.629, b=1.64, g=1.654, bire=0.0250, 2V(Calc)=84, 2V(Meas)=81.8. Dispersion very weak, r > v.

Calculated Properties of Boralsilite

Electron Density:

Bulk Density (Electron Density)=3.00 gm/cc
note: Specific Gravity of Boralsilite =3.06 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_Boralsilite= 1.35 barns/electron
U=PE_Boralsilite x rElectron Density= 4.06 barns/cc.

Radioactivity:

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

Boralsilite Classification

Dana Class:

56.03.03.01 (56)Sorosilicate Si2O7 Groups and O, OH, F. and H2O

(56.03)with [Si2O7] with borate groups

(56.03.03)Dana Group

56.03.03.01 Boralsilite! Al16B6Si2O27 C 2/m 2/m

Strunz Class:

09.BD.30 09 - SILICATES (Germanates)

09.B - Sorosilicates

09.BD -Si2O7 groups with additional anions;

09.BD.30 Boralsilite! Al16B6Si2O27 C 2/m 2/m

Other Boralsilite Information

References:

NAME( MinRec) PHYS. PROP.(Am.Min.,Vol?83,p638-651,1998) OPTIC PROP.(MinRec)

See Also:

Links to other databases for Boralsilite :
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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Print or Cut-and-Paste your Boralsilite Specimen Label here :

Boralsilite

Al16B6Si2O27
Dana No: 56.03.03.01 Strunz No: 09.BD.30
Locality:

Notes:

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