Bentorite (original) (raw)
A valid IMA mineral species
About BentoriteHide
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Formula:
Ca6Cr2(SO4)3(OH)12 · 26H2O
Cr(III) may be partly replaced by Al.
Colour:
Violet to rose-purple
Lustre:
Resinous, Waxy, Earthy
Name:
Named in 1977 by Shulamit Gross in honor of Professor Yaakov K. Ben-Tor [February 13, 1910 Königsberg, East Prussia, Germany - October 29, 2002 La Jolla, California, USA], petrologist and geologist, Scripps Institute of Oceanography, University of California, San Diego, California, USA and Department head of Geology, Hebrew University, Jerusalem, Israel from 1954-1966, for his contributions to the geology and mineralogy of Israel and the Middle East.
Ettringite Group.
The Cr(III) analogue of ettringite.
Type locality: The late Gary Weinberger, who first found bentorite and sent it to a mineralogist for characterization, said that his discovery was made a short hike from the road "near" Arad.
Not to be confused with bentonite.
Unique IdentifiersHide
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Long-form identifier:
mindat:1:1:627:7
d3de445d-cd5c-4340-a1be-fa8145f83f4a
IMA Classification of BentoriteHide
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Classification of BentoriteHide
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7.DG.15
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
D : Sulfates (selenates, etc.) with additional anions, with H2O
G : With large and medium-sized cations; with NO3, CO3, B(OH)4, SiO4 or IO3
31.10.2.2
31 : HYDRATED SULFATES CONTAINING HYDROXYL OR HALOGEN
10 : Miscellaneous
25.4.14
25 : Sulphates
4 : Sulphates of Ca, Sr and Ba
Mineral SymbolsHide
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As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference |
|---|---|---|
| Bto | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of BentoriteHide
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Comment:
Originally said to be vitreous
Colour:
Violet to rose-purple
Cleavage:
Perfect
{1010} perfect; {0001} good
Density:
2.025 g/cm3 (Measured) 2.021 g/cm3 (Calculated)
Optical Data of BentoriteHide
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RI values:
_n_ω = 1.478 _n_ε = 1.484
δ = 0.006
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Optical Extinction:
Parallel
Comments:
O = colorless; E = pale violet purple
Comments:
Absorption E > O
Chemistry of BentoriteHide
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Mindat Formula:
Ca6Cr2(SO4)3(OH)12 · 26H2O
Cr(III) may be partly replaced by Al.
Crystallography of BentoriteHide
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Class (H-M):
3_m_ - Ditrigonal Pyramidal
Cell Parameters:
a = 11.1927 (5) Å, c = 21.7121(5) Å
Unit Cell V:
2,355.60 ų (Calculated from Unit Cell)
Morphology:
Euhedral crystals very rare. Minute crystals (<< 1 mm) show first- and second-order prisms.
X-Ray Powder DiffractionHide
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Image Loading
Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 10.6 Å | (1) |
| 9.656 Å | (100) |
| 6.110 Å | (4) |
| 5.592 Å | (40) |
| 4.980 Å | (4) |
| 4.640 Å | (3) |
| 4.290 Å | (3) |
| 4.030 Å | (3) |
| 3.890 Å | (8) |
| 3.650 Å | (6) |
| 3.600 Å | (10) |
| 3.470 Å | (6) |
| 3.230 Å | (10) |
| 3.020 Å | (5) |
| 2.772 Å | (10) |
| 2.680 Å | (3) |
| 2.610 Å | (3) |
| 2.560 Å | (6) |
| 2.486 Å | (3) |
| 2.410 Å | (3) |
| 2.400 Å | (3) |
| 2.359 Å | (6) |
| 2.206 Å | (8) |
| 2.156 Å | (4) |
| 1.942 Å | (20) |
| 1.908 Å | (5) |
| 1.766 Å | (3) |
| 1.714 Å | (3) |
| 1.671 Å | (3) |
| 1.656 Å | (3) |
| 1.622 Å | (6) |
| 1.515 Å | (6) |
Geological EnvironmentHide
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Type Occurrence of BentoriteHide
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General Appearance of Type Material:
Fine-grained deep purple to light rosey purple masses and veinlet filling.
Place of Conservation of Type Material:
Geochemistry Department, Geological Survey of Israel, Jerusalem, Israel, number SG644.
Fairleigh-Dickinson University, Madison, New Jersey, USA.
Geological Setting of Type Material:
Auto-metamorphosed marble: Hatrurim Formation.
Associated Minerals at Type Locality:
Synonyms of BentoriteHide
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Other Language Names for BentoriteHide
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Relationship of Bentorite to other SpeciesHide
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Other Members of this group:
Common AssociatesHide
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Associated Minerals Based on Photo Data:
Related Minerals - Strunz-mindat GroupingHide
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| 7.DG. | Mathesiusite | K5(UO2)4(SO4)4(VO5) · 4H2O | Tet. 4/m : _P_4/n |
|---|---|---|---|
| 7.DG.05 | Darapskite | Na3(SO4)(NO3) · H2O | Mon. 2/m : _P_21/m |
| 7.DG.10 | Clinoungemachite | (Na, K, Fe, SO4) | Mon. 2/m |
| 7.DG.10 | Humberstonite | Na7K3Mg2(SO4)6(NO3)2 · 6H2O | Trig. 3 : _R_3 |
| 7.DG.10 | Ungemachite | K3Na8Fe(SO4)6(NO3)2 · 6H2O | Trig. 3 : _R_3 |
| 7.DG.15 | Charlesite | Ca6(Al,Si)2(SO4)2[B(OH)4](OH,O)12 · 26H2O | Trig. 3_m_ : P_31_c |
| 7.DG.15 | Ettringite | Ca6Al2(SO4)3(OH)12 · 26H2O | Trig. 3_m_ : P_31_c |
| 7.DG.15 | Jouravskite | Ca3Mn4+(SO4)(CO3)(OH)6 · 12H2O | Hex. 6 : _P_63 |
| 7.DG.15 | Sturmanite | Ca6Fe3+2(SO4)2.5[B(OH)4](OH)12 · 25H2O | Trig. 3_m_ : P_31_c |
| 7.DG.15 | Thaumasite | Ca3(SO4)[Si(OH)6](CO3) · 12H2O | Hex. 6 : _P_63 |
| 7.DG.15 | Carraraite | Ca3(SO4)[Ge(OH)6](CO3) · 12H2O | Hex. |
| 7.DG.15 | Buryatite | Ca3(Si,Fe3+,Al)(SO4)B(OH)4(OH,O)6 · 12H2O | Trig. 3_m_ : P_31_c |
| 7.DG.15 | Birunite | Ca18(SiO3)8.5(CO3)8.5SO4 · 15H2O(?) | |
| 7.DG.15 | Hielscherite | Ca3Si(SO4)(SO3)(OH)6 · 11H2O | Hex. 6 : _P_63 |
| 7.DG.15 | Kottenheimite | Ca 3Si(SO4)2(OH)6 · 12H2O | Hex. 6/m : _P_63/m |
| 7.DG.15 | Imayoshiite | Ca3Al(CO3)[B(OH)4](OH)6 · 12H2O | Hex. 6 : _P_63 |
| 7.DG.15 | Tatarinovite | Ca3Al(SO4)[B(OH)4](OH)6 · 12H2O | Hex. 6 : _P_63 |
| 7.DG.15 | Siwaqaite | Ca6Al2(CrO4)3(OH)12 · 26H2O | Trig. 3_m_ : P_31_c |
| 7.DG.15 | Chiyokoite | Ca3Si(CO3)[B(OH)4]O (OH)5 · 12H2O | Hex. 6 : _P_63 |
| 7.DG.20 | Rapidcreekite | Ca2(SO4)(CO3) · 4H2O | Orth. m m m _(_2/_m_2/_m_2/m ) : P b c n |
| 7.DG.25 | Tatarskite | Ca6Mg2(SO4)2(CO3)2(OH)4Cl4 · 7H2O | Orth. |
| 7.DG.30 | Nakauriite | Cu8(SO4)4(CO3)(OH)6 · 48H2O | Orth. |
| 7.DG.35 | Chessexite | (Na,K)4Ca2(Mg,Zn)3Al8(SO4)10(SiO4)2 · 40H2O | Orth. |
| 7.DG.40 | Carlosruizite | K6(Na,K)4Na6Mg10(SeO4)12(IO3)12 · 12H2O | Trig. 3_m_ _(_32/m ) : _P_3_c_1 |
| 7.DG.40 | Fuenzalidaite | K6(Na,K)4Na6Mg10(SO4)12(IO3)12 · 12H2O | Trig. 3_m_ _(_32/m ) : _P_3_c_1 |
| 7.DG.45 | Chelyabinskite | (Ca,Mg)3(SO4,CO3)2[Si(OH)6] · 9H2O (?) | Orth. |
| 7.DG.55 | Ramazzoite | [Mg8Cu12(PO4)(CO3)4(OH)24(H2O)20][(H0.33SO4)3(H2O)36] | Iso. 43_m_ : P_43_m |
| 7.DG.60 | Witzkeite | Na4K4Ca(NO3)2(SO4)4 · 2H2O | Mon. 2/m : _B_2/b |
Fluorescence of BentoriteHide
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Other InformationHide
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Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for BentoriteHide
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References for BentoriteHide
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Localities for BentoriteHide
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This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the 
symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
Locality ListHide
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- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for references and further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. 
- Good crystals or important locality for species. 
- World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).
All localities listed without proper references should be considered as questionable.
| Israel | |
|---|---|
| Southern District (HaDarom District) Arad ⓘ Arad Stone Quarry | Krüger +2 other references |
| Middle East (TL) | |
| ⓘ Hatrurim Formation (TL) | Gross (1977) |
| Palestine | |
| West Bank Jericho Governorate ⓘ Nabi Musa | Ella V. Sokol et al. (2011) |
| Quds Governorate ⓘ Ma'ale Adumim | - (n.d.) +5 other references |