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.
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:
PEBoralsilite = 1.35 barns/electron U=PEBoralsilite 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
Chemical Formula: 
