Mineralogy Database

Hilgardite Mineral Data

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General Hilgardite Information

Help on Chemical  Formula: Chemical Formula: Ca2B5O9Cl•(H2O)
Help on Composition: Composition: Molecular Weight = 331.67 gm
   Calcium   24.17 %  Ca   33.82 % CaO
   Boron     16.30 %  B    52.48 % B2O3
   Hydrogen   0.61 %  H     5.43 % H2O
   Chlorine  10.69 %  Cl   10.69 % Cl
               -   %   Cl   -2.41 % -O=Cl2   
   Oxygen    48.24 %  O
            ______        ______ 
            100.00 %      100.00 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: Ca2B5O9Cl•(H2O)
Help on Environment: Environment: Minor borate mineral in salt deposits.
Help on IMA Status: IMA Status: Approved IMA 1979
Help on Locality: Locality: Choctaw Salt Dome, Iberville Parish, Louisiana, USA Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named for Eugene W. Hilgard (1833-1916), German-American geologist, one of the first to describe the Loiuisiana salt dome deposits.
Help on Name Pronunciation: Name Pronunciation: Hilgardite + Pronunciation Say HILGARDITE

Hilgardite Image

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  Hilgardite   Boracite

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

Hilgardite Crystallography

Help on Axial Ratios: Axial Ratios: a:b:c =0.9741:1:1.0156
Help on Cell Dimensions: Cell Dimensions: a = 6.297, b = 6.464, c = 6.565, Z = 1; alpha = 74.24°, beta = 61.68°, gamma = 61.26° V = 198.50 Den(Calc)= 2.77
Help on Crystal System: Crystal System: Triclinic - Pedial H-M Symbol (1) Space Group: P1
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 2.88(1), 2.827(0.83), 2.029(0.64),

Physical Properties of Hilgardite

Help on Cleavage: Cleavage: {010} Perfect, {100} Perfect
Help on Color: Color: Colorless.
Help on Density: Density: 2.69
Help on Diaphaneity: Diaphaneity: Transparent
Help on Hardness: Hardness: 5 - Apatite
Help on Luster: Luster: Vitreous (Glassy)
Help on Streak: Streak: white

Optical Properties of Hilgardite

Help on Gladstone-Dale: Gladstone-Dale: CI meas= -0.013 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.021 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2409,KPDmeas= 0.2392,KC= 0.2361
Ncalc = 1.63 - 1.64
Help on Optical Data: Optical Data: Biaxial (+), a=1.63, b=1.636, g=1.664, bire=0.0340, 2V(Calc)=52, 2V(Meas)=35.

Calculated Properties of Hilgardite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=2.66 gm/cc
note: Specific Gravity of Hilgardite =2.69 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.03
Boson Index = 0.97
Help on Photoelectric: Photoelectric: PEHilgardite = 3.87 barns/electron
U=PEHilgardite x rElectron Density= 10.30 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Hilgardite is Not Radioactive

Hilgardite Classification

Help on  Dana Class: Dana Class: (26)Hydrated Borates Containing Hydroxyl or Halogen
  (26.05)Dana Type
  (26.05.14)Hilgardite Hilgardite Ca2B5O9Cl•(H2O) P1 1 Kurgantaite! CaSr[B5O9]Cl•(H2O) P1 1 IMA2007-047! Pb2[B5O9]Cl•0.5H2O Pnn2 mm2
Help on  Strunz Class: Strunz Class: 06.ED.05 06 - BORATES
  06.E - Pentaborates
  06.ED -Tecto-pentaborates
06.ED.05 Hilgardite Ca2B5O9Cl•(H2O) P1 1
06.ED.05 Tyretskite Ca2B5O9(OH)•(H2O) P1 1
06.ED.05 Kurgantaite! CaSr[B5O9]Cl•(H2O) P1 1
06.ED.05 IMA2007-047! Pb2[B5O9]Cl•0.5H2O Pnn2 mm2

Other Hilgardite Information

Help on References: References: NAME( Dana8) PHYS. PROP.(Am.Min.,Vol.78,p1313,1993) OPTIC PROP.(Am.Min.,Vol.78,p1313,1993)
Help on See Also: See Also: Links to other databases for Hilgardite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - Handbook of Mineralogy (MinSocAm)
7 - Handbook of Mineralogy (UofA)
8 - MinDAT
9 - Mineralienatlas (Deutsch)
10 - Online Mineral Museum
11 - QUT Mineral Atlas
12 - Ruff.Info

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Dana No: Strunz No: 06.ED.05





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