Bentorite Mineral Data

Bentorite Mineral Data +

T G Fine Minerals

General Bentorite Information

Chemical Formula:

Ca6(Cr,Al)2(SO4)3(OH)12·26(H2O)

Composition:

Molecular Weight = 1,292.63 gm

Calcium 18.60 % Ca 26.03 % CaO

Aluminum 1.04 % Al 1.97 % Al₂O₃

Chromium 6.03 % Cr 8.82 % Cr₂O₃

Hydrogen 4.99 % H 44.60 % H₂O

Sulfur 7.44 % S 18.58 % SO₃

Oxygen 61.89 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca₆Cr_1.5Al_0.5(SO₄)₃(OH)₁₂·26(H₂O)

IMA Status:

Approved IMA 1980

Locality:

Link to MinDat.org Location Data.

Bentorite Image

Images:

Bentorite

Comments: Violet crystalline bentorite.
Location: Hatrurim Area, West of Dead Sea, Israel. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Bentorite Crystallography

Axial Ratios:

a:c = 1:0.95794

Cell Dimensions:

a = 22.35, c = 21.41, Z = 8; V = 9,261.95 Den(Calc)= 1.85

Crystal System:

Hexagonal - Dihexagonal DipyramidalH-M Symbol (6/m 2/m 2/m) Space Group: P 6₃/mmc

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

By Intensity(I/I_o): 9.656(1), 5.592(0.4), 1.942(0.2),

Physical Properties of Bentorite

Cleavage:

[1010] Perfect

Color:

Violet, Light violet.

Density:

2.025

Diaphaniety:

Transparent

Hardness:

2 - Gypsum

Luster:

Vitreous (Glassy)

Streak:

violet

Optical Properties of Bentorite

Gladstone-Dale:

CI meas= 0.116 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= 0.033 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.26,KPDmeas= 0.2375,KC= 0.2688

Optical Data:

Uniaxial (+), w=1.478, e=1.484, bire=0.0060.

Calculated Properties of Bentorite

Electron Density:

r_electron=1.93 gm/cc
note: r_Bentorite=1.85 gm/cc.

Fermion Index

Fermion Index = 0.00684
Boson Index = 0.99316

Photoelectric:

PE_Bentorite= 4.06 barns/electron
U=PE_Bentorite x r_electron= 7.84 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Bentorite is Not Radioactive

Bentorite Classification

Dana Class:

31.10.2.2 (31)Hydrated Sulfates Containing Hydroxyl or Halogen

(31.10)miscellaneous

(31.10.2)Dana Group

31.10.2.1 Ettringite Ca6Al2(SO4)3(OH)12·26(H2O) P 6₃/mmc 6/m 2/m 2/m

31.10.2.2 Bentorite Ca6(Cr,Al)2(SO4)3(OH)12·26(H2O) P 6₃/mmc 6/m 2/m 2/m

31.10.2.3 Buryatite! Ca3(Si,Fe,Al)[SO4][B(OH)4](OH,O)6·12(H2O) P 3₁c 3m

Strunz Class:

VI/D.13-20 VI - Sulfates,Chromates,Molybdates and Tungstates

VI/D - Water-bearing sulfates with unfamiliar anions. cations of medium and very big size

VI/D.13 - Ettringite group, Ettringite - Sturmanite

VI/D.13-10 Ettringite Ca6Al2(SO4)3(OH)12·26(H2O) P 6₃/mmc 6/m 2/m 2/m

VI/D.13-20 Bentorite Ca6(Cr,Al)2(SO4)3(OH)12·26(H2O) P 6₃/mmc 6/m 2/m 2/m

VI/D.13-30 Jouravskite Ca3Mn(SO4,CO3)2(OH)6·12(H2O) P 6₃/m 6/m

VI/D.13-35 Carraraite! Ca3Ge(OH)6(SO4)(CO3)·12H2O P 6₃/m, or P 6₃ Hex

VI/D.13-40 Charlesite Ca6(Al,Si)2(SO4)2B(OH)4(OH,O)12·26(H2O) P 3₁c 3m

VI/D.13-50 Sturmanite Ca6(Fe,Al,Mn)2(SO4)2[B(OH)4](OH)12·25(H2O) P 3₁c 3m

VI/D.13-60 Buryatite! Ca3(Si,Fe,Al)[SO4][B(OH)4](OH,O)6·12(H2O) P 3₁c 3m

Other Bentorite Information

References:

PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

Links to other databases for Bentorite :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 - EUROmin Project 4 -Google Images 5 -Google Scholar 6 -Handbook of Mineralogy (UofA) 7 -MinDAT 8 -MinMax(Deutsch) 9 -MinMax(English) 10 -Mineralienatlas (Deutsch) 11 -QUT Mineral Atlas 12 -École des Mines de Paris

Search for Bentorite using:

[ALTAVISTA] [AOL] [All-The-Web] [HotBot] [Ixquick] [MAMMA] [MSN.COM] [Netscape] [Scirus] [Teoma] [Wikipedia] [YAHOO]

Visit our Advertisers for Bentorite :

AA Mineral Specimens

B & L Fine Minerals

Crystal Vaults

Dan Weinrich Fine Minerals

Dan Weinrich Auctions

John Betts Fine Minerals

Mason's Minerals

Mineral News

Mineral of the Month Club

MineralsWeb Fine Minerals

Rockshop.cz

T G Fine Minerals

Wrights Rock Shop

Translate Bentorite Mineral Data :

Ask about Bentorite here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Español

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

Bentorite

Ca6(Cr,Al)2(SO4)3(OH)12·26(H2O)
Dana No: 31.10.2.2 Strunz No: VI/D.13-20
Locality:

Notes: