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Boralsilite

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Formula:
Al16B6Si2O37
Lustre:
Vitreous
Crystal System:
Monoclinic
Name:
Named after its composition, containing BORon, ALuminum, and SILicon.
First anhydrous Al-B-silicate to be discovered in nature. At Stornes Peninsula the borasilite may be partly replaced by diaspore.


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Classification of BoralsiliteHide

Approved
9.BD.30

9 : SILICATES (Germanates)
B : Sorosilicates
D : Si2O7 groups, with additional anions; cations in tetrahedral [4] and greater coordination

Physical Properties of BoralsiliteHide

Vitreous

Optical Data of BoralsiliteHide

Type:
Biaxial (+)
RI values:
nα = 1.629 nβ = 1.640 nγ = 1.654
2V:
Measured: 81° , Calculated: 84°
Max Birefringence:
δ = 0.025
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Moderate
Dispersion:
very weak

Chemical Properties of BoralsiliteHide

Formula:
Al16B6Si2O37
IMA Formula:
Al16B6O30(Si2O7)

Crystallography of BoralsiliteHide

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/m
Setting:
C2/m
Cell Parameters:
a = 14.767 Å, b = 5.574 Å, c = 15.079 Å
β = 91.96°
Ratio:
a:b:c = 2.649 : 1 : 2.705
Unit Cell V:
1,240.45 ų (Calculated from Unit Cell)
Morphology:
Prisms in open clusters or tight bundles up to 1 cm long.

Type Occurrence of BoralsiliteHide

General Appearance of Type Material:
Forms a single patch of fibrous aggregates of fine prisms in a quartzrich part of the specimen (Larsemanns Hills)
Place of Conservation of Type Material:
In the National Museum of Natural History, Smithsonian Institution as NMNH 171403 and the Almgjotheii specimen as NMNH 171404.
Chemical Analysis of Type Material:
SiO212.67 %
MgO0.23 %
FeO1.10 %
Al2O369.15 %
B2O316.775 %
BeO0.094 %
Total:100.019 %
Geological Setting of Type Material:
Pegmatites cutting granulite-facies metapelitic rocks.
Associated Minerals at Type Locality:
Reference:
Grew, E.S., McGee, J.J., Yates, M.G., Peacor, D.R., Rouse, R.C., Huijsmans, J.P.P., Shearer, C.K., Wiedenbeck, M., Thost, D.E., and Su, S.-C. (1998): Boralsilite (Al16B6Si2O37): A new mineral related to sillimanite from pegmatites in granulite-facies rocks. American Mineralogist: 83: 638-651

Synonyms of BoralsiliteHide

Other Language Names for BoralsiliteHide

Common AssociatesHide

Associated Minerals Based on Photo Data:
Tourmaline4 photos of Boralsilite associated with Tourmaline on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

9.BD.05BertranditeBe4(Si2O7)(OH)2Orth. mm2 : Cmc21
9.BD.10HemimorphiteZn4Si2O7(OH)2 · H2OOrth. mm2 : Imm2
9.BD.15JunitoiteCaZn2Si2O7 · H2OOrth. mm2
9.BD.20Axinite-(Fe)Ca2Fe2+Al2BSi4O15OHTric. 1 : P1
9.BD.20Axinite-(Mg)Ca2MgAl2BSi4O15OHTric.
9.BD.20Axinite-(Mn)Ca2Mn2+Al2BSi4O15(OH)Tric. 1 : P1
9.BD.20TinzeniteCa2Mn2+4Al4[B2Si8O30](OH)2Tric.
9.BD.25VistepiteSnMn4B2Si4O16(OH)2Tric. 1
9.BD.35Werdingite(Mg,Fe)2Al14Si4B4O37Tric.

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for BoralsiliteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Edward S. Grew, Heribert A. Graetsch, Birgit Pöter, Martin G. Yates, Ian Buick, Heinz-Jürgen Bernhardt, Werner Schreyer, Günter Werding, Christopher J. Carson, and Geoffrey L. Clarke (2008) Boralsilite, Al16B6Si2O37, and “boron-mullite:” Compositional variations and associated phases in experiment and nature. American Mineralogist 93:283-299
Grew, E.S., McGee, J.J., Yates, M.G., Peacor, D.R., Rouse, R.C., Huijsmans, J.P.P., Shearer, C.K., Wiedenbeck, M., Thost, D.E., and Su, S.-C. (1998) Boralsilite (Al16B6Si2O37): A new mineral related to sillimanite from pegmatites in granulite-facies rocks. American Mineralogist: 83: 638-651.
Pöter, B., Werding, G., Schreyer, W., Bernhardt, H.-J. (1998) Synthesis and properties of the new borosilicate mineral boralsilite. Berichte Deutschen Mineral Gesell, Beiheft z European Journal of Mineralogy: 10(1): 220.
American Mineralogist (1999): 84: 1152-1161.

Internet Links for BoralsiliteHide

Localities for BoralsiliteHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
Antarctica
 
  • Eastern Antarctica
    • Princess Elizabeth Land
      • Ingrid Christensen Coast
        • Prydz Bay
Wadokski, E. R. Grew, E.S. & Yates, M.G. (2011): Compositional evolution of tourmaline-supergroup minerals from granitic pegmatites in the Larsemann Hills, East Antartica. Canadian Mineralogist. 49: 382-405; Maas, R., Grew, E. S., & Carson, C. J. (2015). Isotopic Constraints (Pb, Rb-Sr, Sm-Nd) on the Sources of Early Cambrian Pegmatites with Boron and Beryllium Minerals in the Larsemann Hills, Prydz Bay, Antarctica. The Canadian Mineralogist, 53:249-272
Grew, E. S. et al. (1998): Boralsilite (Al16B6Si2O37); a new mineral related to sillimanite from pegmatites in granulite-facies rocks . American Mineralogist 83: 638-651
Czech Republic
 
  • Moravia (Mähren; Maehren)
    • Vysočina Region
      • Žďár nad Sázavou District
        • Křižanov
CEMPÍREK, Jan a Milan NOVÁK a Zdeněk DOLNÍČEK a Jana KOTKOVÁ a Radek ŠKODA. Crystal chemistry and origin of grandidierite, ominelite, boralsilite, and werdingite from the Bory Granulite Massif, Czech Republic American Mineralogist, Mineralogical Society of America, 95, 10, od s. 1533-1547, 15 s. ISSN 0003-004X. 2010
Madagascar
 
  • Antananarivo Province
    • Vakinankaratra Region
      • Antsirabe II District
        • Ibity Commune
          • Sahatany Valley
Novák, M., Cempírek, J., Gadas, P., Škoda, R., Galiová, M. V., Pezzotta, F. and Groat, L. A. (2015): Boralsilite and Li, Be-bearing "Boron Mullite" Al8B2Si2O19, Breakdown products of spodumene from the Manjaka pegmatite, Sahatany valley, Madagascar. Canadian Mineralogist. 53: 357-374
Norway (TL)
 
  • Rogaland
    • Lund
      • Flatestøl
Grew, E. S. et al. (1998): Boralsilite (Al 16 B 6 Si 2 O 37 ); a new mineral related to sillimanite from pegmatites in granulite-facies rocks . American Mineralogist 83: 638-651
Mineral and/or Locality  
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