General Boracite Information
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Chemical Formula: |
Mg3B7O13Cl |
Composition: |
Molecular Weight = 392.03 gm |
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Magnesium 18.60 % Mg 30.84 % MgO |
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Boron 19.30 % B 62.15 % B2O3 |
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Chlorine 9.04 % Cl 9.04 % Cl |
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- % Cl -2.04 % -O=Cl2 |
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Oxygen 53.06 % O |
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______ ______ |
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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 |
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PDF 5-710 |
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Boracite Image |
Images:
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Images:
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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 |
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Images:
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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 |
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Boracite Crystallography
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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 |
X Ray Diffraction: |
By Intensity(I/Io): 2.058(1), 3.044(0.7), 2.72(0.5), |
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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]
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Physical Properties of Boracite
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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 |
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Optical Properties of Boracite
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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 |
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Calculated Properties of Boracite
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Electron Density: |
relectron=2.89 gm/cc note: rBoracite =2.95 gm/cc. |
Fermion Index |
Fermion Index = 0.05726 Boson Index = 0.94274 |
Photoelectric: |
PEBoracite = 1.21 barns/electron U=PEBoracite x relectron= 3.50 barns/cc. |
Radioactivity: |
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Boracite is Not Radioactive |
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Boracite Classification
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Dana Class: |
25.6.1.1 (25)Anhydrous Borates Containing Hydroxyl or Halogen |
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(25.6)Dana Type |
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(25.6.1)Boracite Group (Orthorhombic: Rca21) |
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25.6.1.1 Boracite Mg3B7O13Cl P ca21 mm2 |
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25.6.1.2 Ericaite (Fe,Mg,Mn)3B7O13Cl P ca21 mm2 |
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25.6.1.3 Chambersite Mn3B7O13Cl P ca21 mm2 |
Strunz Class: |
V/L.04-10 V - Nitrates, Carbonates and Borates |
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V/L - Shelly borates with [BO2]1- to [B6O10]2- |
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V/L.04 - Boracite - Congolite series |
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V/L.04-10 Boracite Mg3B7O13Cl P ca21 mm2 |
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V/L.04-20 Ericaite (Fe,Mg,Mn)3B7O13Cl P ca21 mm2 |
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V/L.04-30 Chambersite Mn3B7O13Cl P ca21 mm2 |
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V/L.04-35 Trembathite (Mg,Fe)3B7O13Cl R 3c 3m |
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V/L.04-40 Congolite (Fe,Mg,Mn)3B7O13Cl R 3c 3m |
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Other Boracite Information
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References: |
NAME( Duda&Rejl90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990) |
See Also: |
Links to other databases for Boracite :
1 -Am. Min. Crystal Structure Database
2 - Amethyst Galleries' Mineral Gallery
3 - Applied Mineralogy
4 -Athena
5 - Crocoite.com Mineral Locations
6 -Google Images
7 -Google Scholar
8 -Handbook of Mineralogy (UofA)
9 - HyperPhysics
10 -MinDAT
11 -MinMax(Deutsch)
12 -MinMax(English)
13 -Mineralienatlas (Deutsch)
14 -QUT Mineral Atlas
15 - WWW-MINCRYST
16 -École des Mines de Paris
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Print or Cut-and-Paste your Boracite Specimen Label here :
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Boracite
Mg3B7O13Cl
Dana No: 25.6.1.1 Strunz No: V/L.04-10
Locality:
Notes:
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