Boracite Mineral Data

Boracite Mineral Data +

General Boracite Information

Chemical Formula:

Mg3B7O13Cl

Composition:

Molecular Weight = 392.03 gm

Magnesium 18.60 % Mg 30.84 % MgO

Boron 19.30 % B 62.15 % B₂O₃

Chlorine 9.04 % Cl 9.04 % Cl

- % Cl -2.04 % -O=Cl₂

Oxygen 53.06 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Mg₃B₇O₁₃Cl

Environment:

Marine evaporites.

IMA Status:

Valid Species (Pre-IMA) 1789

Locality:

Luneburg and Hildesheim, Germany. Link to MinDat.org Location Data.

Name Origin:

Named after its composition containing boron.

Synonym:

ICSD 9290

PDF 5-710

Boracite Image

Images:

Boracite

Comments: Clear, pale green pseudo-cubic boracite crystal.
Location: Sonderhausen, Thuringia, Germany. Scale: Size Not Given.
© Lou Perloff / Photo Atlas of Minerals

Images:

Boracite

Comments: A greenish crystal of boracite, a tetrahedron modified by cube and dodecahedral faces.
Location: Bernburg, Sachsen-Anhalt, Germany. Scale: Picture size 5 mm.
© Thomas Witzke / Abraxas-Verlag

Images:

Boracite Hilgardite

Comments: Sub-mm reddish orange crystals of hilgardite on white boracite.
Location: Boulby Mine, Loftus, Cleveland, Great Britain. Scale: 1.5 x 2.5 cm.
© John Veevaert

Boracite Crystallography

Axial Ratios:

a:b:c =1:1:1.4168

Cell Dimensions:

a = 8.54, b = 8.54, c = 12.1, Z = 4; V = 882.47 Den(Calc)= 2.95

Crystal System:

Orthorhombic - PyramidalH-M Symbol (mm2) Space Group: P ca2₁

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

By Intensity(I/I_o): 2.058(1), 3.044(0.7), 2.72(0.5),

Forms:

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Crystal Structure:

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Sueno S , Clark J R , Papike J J , Konnert J A , American Mineralogist , 58 (1973) p.691-697, Crystal-structure refinement of cubic boracite, T = 400 C

View Additional jPOWD Structure files for Boracite
[1]

Physical Properties of Boracite

Cleavage:

None

Color:

Blue green, Colorless, Gray, Yellow, White.

Density:

2.9

Diaphaniety:

Subtransparent to translucent

Fracture:

Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.

Habit:

Crystalline - Fine - Occurs as well-formed fine sized crystals.

Habit:

Disseminated - Occurs in small, distinct particles dispersed in matrix.

Hardness:

7 - Quartz

Luminescence:

Non-fluorescent.

Luster:

Vitreous - Adamantine

Streak:

white

Optical Properties of Boracite

Gladstone-Dale:

CI meas= -0.024 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= -0.007 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2254,KPDmeas= 0.2293,KC= 0.2239

Optical Data:

Biaxial (+), a=1.658-1.6622, b=1.662-1.667, g=1.668-1.673, bire=0.0100-0.0108

Calculated Properties of Boracite

Electron Density:

r_electron=2.89 gm/cc
note: r_Boracite=2.95 gm/cc.

Fermion Index

Fermion Index = 0.05726
Boson Index = 0.94274

Photoelectric:

PE_Boracite= 1.21 barns/electron
U=PE_Boracite x r_electron= 3.50 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Boracite is Not Radioactive

Boracite Classification

Dana Class:

25.6.1.1 (25)Anhydrous Borates Containing Hydroxyl or Halogen

(25.6)Dana Type

(25.6.1)Boracite Group (Orthorhombic: Rca21)

25.6.1.1 Boracite Mg3B7O13Cl P ca2₁ mm2

25.6.1.2 Ericaite (Fe,Mg,Mn)3B7O13Cl P ca2₁ mm2

25.6.1.3 Chambersite Mn3B7O13Cl P ca2₁ mm2

Strunz Class:

V/L.04-10 V - Nitrates, Carbonates and Borates

V/L - Shelly borates with [BO2]1- to [B6O10]2-

V/L.04 - Boracite - Congolite series

V/L.04-10 Boracite Mg3B7O13Cl P ca2₁ mm2

V/L.04-20 Ericaite (Fe,Mg,Mn)3B7O13Cl P ca2₁ mm2

V/L.04-30 Chambersite Mn3B7O13Cl P ca2₁ mm2

V/L.04-35 Trembathite (Mg,Fe)3B7O13Cl R 3c 3m

V/L.04-40 Congolite (Fe,Mg,Mn)3B7O13Cl R 3c 3m

Other Boracite Information

References:

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

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Print or Cut-and-Paste your Boracite Specimen Label here :

Boracite

Mg3B7O13Cl
Dana No: 25.6.1.1 Strunz No: V/L.04-10
Locality:

Notes: