ALMOST THERE!. Help us with a final push needed to keep mindat.org running. Click here to help.
Catawiki are hosting a mindat.org benefit auction. All proceeds to mindat.org! BID NOW
Log InRegister
Home PageAbout MindatThe Mindat ManualHistory of MindatCopyright StatusWho We AreContact UsAdvertise on Mindat
Donate to MindatCorporate SponsorshipSponsor a PageSponsored PagesMindat AdvertisersAdvertise on Mindat
Learning CenterWhat is a mineral?The most common minerals on earthInformation for EducatorsMindat Articles
Minerals by PropertiesMinerals by ChemistryAdvanced Locality SearchRandom MineralRandom LocalitySearch by minIDLocalities Near MeSearch ArticlesSearch GlossaryMore Search Options
Search For:
Mineral Name:
Locality Name:
Keyword(s):
 
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
Mining CompaniesStatisticsThe ElementsUsersBooks & MagazinesMineral MuseumsMineral Shows & EventsThe Mindat DirectoryDevice Settings
Photo SearchPhoto GalleriesNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day Gallery

Bentorite

This page is currently not sponsored. Click here to sponsor this page.
Hide all sections | Show all sections

About BentoriteHide

Formula:
Ca6(Cr3+,Al)2(SO4)3(OH)12 · 26H2O
Colour:
Violet to rose-purple
Lustre:
Resinous, Waxy, Earthy
Hardness:
2
Specific Gravity:
2.025
Crystal System:
Hexagonal
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.

Not to be confused with bentonite.


Classification of BentoriteHide

Approved
Approval Year:
1979
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

Physical Properties of BentoriteHide

Resinous, Waxy, Earthy
Transparency:
Transparent
Comment:
Originally said to be vitreous
Colour:
Violet to rose-purple
Streak:
Very pale purple
Hardness:
Cleavage:
Perfect
{10-0} perfect; {0001} good
Fracture:
Sub-Conchoidal
Density:
2.025 g/cm3 (Measured)    2.021 g/cm3 (Calculated)

Optical Data of BentoriteHide

Type:
Uniaxial (+)
RI values:
nω = 1.478 nε = 1.484
Birefringence:
0.006
Max Birefringence:
δ = 0.006
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Moderate
Optical Extinction:
Parallel
Pleochroism:
Visible
Comments:
O = colorless; E = pale violet purple
Comments:
Absorption E > O

Chemical Properties of BentoriteHide

Formula:
Ca6(Cr3+,Al)2(SO4)3(OH)12 · 26H2O
IMA Formula:
Ca6Cr2(SO4)3(OH)12 · 26H2O

Crystallography of BentoriteHide

Crystal System:
Hexagonal
Class (H-M):
6/mmm (6/m 2/m 2/m) - Dihexagonal Dipyramidal
Space Group:
P63/mmc
Setting:
P63/mmc
Cell Parameters:
a = 22.35 Å, c = 21.41 Å
Ratio:
a:c = 1 : 0.958
Unit Cell V:
9,261.95 ų (Calculated from Unit Cell)
Z:
8
Morphology:
Euhedral crystals very rare. Minute crystals (<< 1 mm) show first- and second-order prisms.
Twinning:
{10-10}

X-Ray Powder DiffractionHide

Image Loading

Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
d-spacingIntensity
9.66 (100)
5.59 (40)
3.89 (10)
3.60 (10)
3.23 (10)
2.77 (10)
2.21 (10)
1.94 (20)
Comments:
ICDD 33-248

Type Occurrence of BentoriteHide

General Appearance of Type Material:
Fine-grained deep purple to light rosey purple masses and veinlet filling.
Geological Setting of Type Material:
Auto-metamorphosed marble: Hatrurim Formation
Associated Minerals at Type Locality:

Synonyms of BentoriteHide

Other Language Names for BentoriteHide

German:Bentorit
Spanish:Bentorita

Relationship of Bentorite to other SpeciesHide

Other Members of this group:
BuryatiteCa3(Si,Fe,Al)(SO4)[B(OH)4]O(OH)5 · 12H2O
CarraraiteCa3(SO4)[Ge(OH)6](CO3) · 12H2OHex.
CharlesiteCa6(Al,Si)2(SO4)2[B(OH)4](OH,O)12 · 26H2OTrig. 3m : P3 1c
EttringiteCa6Al2(SO4)3(OH)12 · 26H2OTrig. 3m : P3 1c
HielscheriteCa3Si(SO4)(SO3)(OH)6 · 11H2OHex. 6 : P63
ImayoshiiteCa3Al(CO3)[B(OH)4](OH)6 · 12H2OHex. 6 : P63
JouravskiteCa3Mn4+(SO4)(CO3)(OH)6 · 12H2OHex.
KottenheimiteCa 3Si(SO4)2(OH)6·12H2O Hex. 6/m : P63/m
Micheelsenite(Ca,Y)3Al(HPO4,CO3)(CO3)(OH)6 · 12H2OHex.
SturmaniteCa6(Fe3+,Al,Mn3+)2(SO4)2[B(OH)4](OH)12 · 25H2OTrig. 3m : P3 1c
TatarinoviteСа3Al(SO4)[B(OH)4](OH)6·12H2OHex. 6 : P63
ThaumasiteCa3(SO4)[Si(OH)6](CO3) · 12H2OHex. 6 : P63

Related Minerals - Nickel-Strunz GroupingHide

7.DG.05DarapskiteNa3(SO4)(NO3) · H2OMon. 2/m
7.DG.10Clinoungemachite(Na, K, Fe, SO4)Mon. 2/m
7.DG.10HumberstoniteNa7K3Mg2(SO4)6(NO3)2 · 6H2OTrig. 3 : R3
7.DG.10UngemachiteK3Na8Fe(SO4)6(NO3)2 · 6H2OTrig. 3 : R3
7.DG.15CharlesiteCa6(Al,Si)2(SO4)2[B(OH)4](OH,O)12 · 26H2OTrig. 3m : P3 1c
7.DG.15EttringiteCa6Al2(SO4)3(OH)12 · 26H2OTrig. 3m : P3 1c
7.DG.15JouravskiteCa3Mn4+(SO4)(CO3)(OH)6 · 12H2OHex.
7.DG.15SturmaniteCa6(Fe3+,Al,Mn3+)2(SO4)2[B(OH)4](OH)12 · 25H2OTrig. 3m : P3 1c
7.DG.15ThaumasiteCa3(SO4)[Si(OH)6](CO3) · 12H2OHex. 6 : P63
7.DG.15CarraraiteCa3(SO4)[Ge(OH)6](CO3) · 12H2OHex.
7.DG.15BuryatiteCa3(Si,Fe,Al)(SO4)[B(OH)4]O(OH)5 · 12H2O
7.DG.20RapidcreekiteCa2(SO4)(CO3) · 4H2OOrth.
7.DG.20KorkinoiteCa4(SO4)2(CO3)2 · 9(H2O)Orth. mmm (2/m 2/m 2/m) : Pmmm
7.DG.25TatarskiteCa6Mg2(SO4)2(CO3)2(OH)4Cl4 · 7H2OOrth.
7.DG.30NakauriiteCu8(SO4)4(CO3)(OH)6 · 48H2OOrth.
7.DG.35Chessexite(Na,K)4Ca2(Mg,Zn)3Al8(SO4)10(SiO4)2 · 40H2OOrth.
7.DG.40CarlosruiziteK6(Na,K)4Na6Mg10(SeO4)12(IO3)12 · 12H2OTrig. 3m (3 2/m) : P3c1
7.DG.40FuenzalidaiteK6(Na,K)4Na6Mg10(SO4)12(IO3)12 · 12H2OTrig. 3m (3 2/m) : P3c1
7.DG.45Chelyabinskite(Ca,Mg)3(SO4,CO3)2[Si(OH)6] · 9H2O (?)Orth.

Related Minerals - Dana Grouping (8th Ed.)Hide

31.10.2.1EttringiteCa6Al2(SO4)3(OH)12 · 26H2OTrig. 3m : P3 1c

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

25.4.1AnhydriteCaSO4Orth. mmm (2/m 2/m 2/m)
25.4.2BassaniteCaSO4 · 0.5H2OMon. 2 : B2
25.4.3GypsumCaSO4 · 2H2OMon. 2/m
25.4.4GlauberiteNa2Ca(SO4)2Mon. 2/m : B2/b
25.4.5CesaniteNa3Ca2(SO4)3(OH)Hex.
25.4.6EugsteriteNa4Ca(SO4)3 · 2H2OMon.
25.4.7HydroglauberiteNa10Ca3(SO4)8 · 6H2OMon.
25.4.8SyngeniteK2Ca(SO4)2 · H2OMon. 2/m : P21/m
25.4.9GörgeyiteK2Ca5(SO4)6 · H2OMon.
25.4.10PolyhaliteK2Ca2Mg(SO4)4 · 2H2OTric. 1
25.4.11Koktaite(NH4)2Ca(SO4)2 · H2OMon.
25.4.12Ye'elimiteCa4Al6(SO4)O12Iso.
25.4.13EttringiteCa6Al2(SO4)3(OH)12 · 26H2OTrig. 3m : P3 1c
25.4.15CelestineSrSO4Orth. mmm (2/m 2/m 2/m) : Pnma
25.4.16KalistrontiteK2Sr(SO4)2Trig.
25.4.17BaryteBaSO4Orth. mmm (2/m 2/m 2/m) : Pnma

Fluorescence of BentoriteHide

Not fluorescent

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for BentoriteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Gross, S. (1980) Bentorite. A new mineral from the Hatrurim Area, west of the Dead Sea, Israel. Israel J. of Earth Sci., 29, 81–84. [abstract in Amer. Mineral., 66 (1981), 639]
Yurii V. Seryotkin, Ella V. Sokol, Svetlana N. Kokh, Mikhail N. Murashko (2018): Natural Cr3+-rich ettringite: occurrence, properties, and crystal structure. Phys. Chem. Minerals 45, 279-292. [Cr/(Cr + Al) ratios up to 0.40–0.50]

Internet Links for BentoriteHide

Localities for BentoriteHide

ⓘ - Click for 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 (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
Israel (TL)
 
  • Negev
Gross, S. (1977): The Mineralogy of the Hatrurim Formation, Israel. Geological Survey of Israel, Bulletin no. 70, 80 pp.
Palestine
 
  • West Bank
    • Hatrurim formation
Sokol, E.V., Gaskova, O.L., Kokh, S.N., Kozmenko, O.A., Seryotkin, Y.V., Vapnik, Y., Murashko, M.N. (2011): Chromatite and its Cr3+- and Cr6+-bearing precursor minerals from the Nabi Musa Mottled Zone complex, Judean Desert. American Mineralogist 96, 659-674.; Natural History Museum Vienna collection
Ella V. Sokol, Olga L. Gaskova, Svetlana N. Kokh, Olga A. Kozmenko, Yuri V. Seryotkin, Yevgeny Vapnik, and Michail N. Murashko (2011): Chromatite and its Cr3+- and Cr6+-bearing precursor minerals from the Nabi Musa Mottled Zone complex, Judean Desert. American Mineralogist, 96, 659-674.
Mineral and/or Locality  
Mindat.org is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2018, except where stated. Mindat.org relies on the contributions of thousands of members and supporters.
Privacy Policy - Terms & Conditions - Contact Us Current server date and time: December 19, 2018 11:31:58 Page generated: November 9, 2018 14:37:00
Go to top of page