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Benstonite
A valid IMA mineral species
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About Benstonite
Formula:
Ba6Ca6Mg(CO3)13
Ba may be replaced by minor Sr, and Ca by minor Mn.
Colour:
White to ivory, very pale yellow, pale yellowish brown
Lustre:
Vitreous
Hardness:
3 - 4
Specific Gravity:
3.956
Crystal System:
Trigonal
Name:
Named in honor of Orlando J. Benston (February 1901, Whalan, Minnesota, USA - 20 January 1966, Malvern, Arkansas, USA), an ore dressing metallurgist for the Baroid Division, National Lead Co., Malvern, Arkansas, USA, who supplied the first specimens.
Unique Identifiers
Mindat ID:
626
Long-form identifier:
mindat:1:1:626:8
Similar Names
| Bentonite | A rock subtype |
IMA Classification of Benstonite
Approved
First published:
1961
Classification of Benstonite
5.AB.55
5 : CARBONATES (NITRATES)
A : Carbonates without additional anions, without H2O
B : Alkali-earth (and other M2+) carbonates
5 : CARBONATES (NITRATES)
A : Carbonates without additional anions, without H2O
B : Alkali-earth (and other M2+) carbonates
14.2.3.1
14 : ANHYDROUS NORMAL CARBONATES
2 : AB(XO3)2
14 : ANHYDROUS NORMAL CARBONATES
2 : AB(XO3)2
11.5.7
11 : Carbonates
5 : Carbonates of Sr and Ba
11 : Carbonates
5 : Carbonates of Sr and Ba
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Ben | 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 Benstonite
Vitreous
Transparency:
Translucent
Colour:
White to ivory, very pale yellow, pale yellowish brown
Streak:
White
Hardness:
3 - 4 on Mohs scale
Cleavage:
Distinct/Good
Good on (31_42)
Good on (31_42)
Density:
3.956 g/cm3 (Measured) 3.695 g/cm3 (Calculated)
Optical Data of Benstonite
Type:
Uniaxial (-)
RI values:
nω = 1.690 nε = 1.527
Max. Birefringence:
δ = 0.163
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized uniaxial interference figure - the conoscopic
(convergent-light, Bertrand-lens-in) view, for a grain cut with the optic axis
centred and vertical. The coloured rings are isochromatics, computed with the
same physics as the Michel-Lévy bar above; the dark cross is the isogyre.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
Chemistry of Benstonite
Mindat Formula:
Ba6Ca6Mg(CO3)13
Ba may be replaced by minor Sr, and Ca by minor Mn.
Ba may be replaced by minor Sr, and Ca by minor Mn.
Element Weights:
Crystallography of Benstonite
Crystal System:
Trigonal
Class (H-M):
3 - Rhombohedral
Space Group:
R3
Cell Parameters:
a = 18.280 Å, c = 8.652 Å
Ratio:
a:c = 1 : 0.473
Unit Cell V:
2,503.80 ų (Calculated from Unit Cell)
Z:
3
Morphology:
Rhombohedral crystals to 1cm.
Crystal Structure
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0014709 | Benstonite | Effenberger H (1979) Kristallstruktur und chemische formel des benstonits, Ba6Ca6Mg(CO3)13 Neues Jahrbuch fur Mineralogie, Abhandlungen 136 326-337 | 1979 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Loading XRD data...
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.08 Å | (95) |
| 3.92 Å | (38) |
| 2.536 Å | (28) |
| 2.127 Å | (23) |
| 1.905 Å | (17) |
| 4.19 Å | (16) |
| 3.53 Å | (10) |
Comments:
Magnet Cove, Arkansas, USA. Data from the type description. The intensity of the strongest peak is given as 95, rather than 100.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| High-? alteration and/or metamorphism | |
| 32 : Ba/Mn/Pb/Zn deposits, including metamorphic deposits | |
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 36 : Carbonatites, kimberlites, and related igneous rocks |
Geological Setting:
Barite deposits
Type Occurrence of Benstonite
General Appearance of Type Material:
White cleavable masses, with cleavage faces to 1 cm across.
Place of Conservation of Type Material:
Mineralogische Sammlungen, Mineralogisch-Petrographisches Institut, Universität Göttingen, Göttingen, Germany, number S.21.3.5.1 (holotype).
National Museum of Natural History, Washington, D.C., USA numbers 120234 and 120236 (type).
National Museum of Natural History, Washington, D.C., USA numbers 120234 and 120236 (type).
Geological Setting of Type Material:
Baryte deposit.
Associated Minerals at Type Locality:
Other Language Names for Benstonite
Common Associates
Associations Based on Photo Data:
| 47 photos of Benstonite associated with Fluorite | CaF2 |
| 30 photos of Benstonite associated with Calcite | CaCO3 |
| 14 photos of Benstonite associated with Alstonite | BaCa(CO3)2 |
| 8 photos of Benstonite associated with Baryte | BaSO4 |
| 7 photos of Benstonite associated with Sphalerite | ZnS |
| 1 photo of Benstonite associated with Witherite | BaCO3 |
Related Minerals - Strunz-mindat Grouping
| 5.AB.05 | Siderite | FeCO3 |
| 5.AB.05 | Rhodochrosite | MnCO3 |
| 5.AB.05 | Calcite | CaCO3 |
| 5.AB.05 | Smithsonite | ZnCO3 |
| 5.AB.05 | Gaspéite | NiCO3 |
| 5.AB.05 | Spherocobaltite | CoCO3 |
| 5.AB.05 | Magnesite | MgCO3 |
| 5.AB.05 | Otavite | CdCO3 |
| 5.AB.05 va | 'Parakutnohorite' | |
| 5.AB.10 | Dolomite | CaMg(CO3)2 |
| 5.AB.10 | Minrecordite | CaZn(CO3)2 |
| 5.AB.10 | Škáchaite | CaCo(CO3)2 |
| 5.AB.10 | Ankerite | Ca(Fe2+,Mg)(CO3)2 |
| 5.AB.10 | Kutnohorite | CaMn2+(CO3)2 |
| 5.AB.15 | Aragonite | CaCO3 |
| 5.AB.15 | Cerussite | PbCO3 |
| 5.AB.15 | Witherite | BaCO3 |
| 5.AB.15 | Strontianite | SrCO3 |
| 5.AB.20 | Vaterite | CaCO3 |
| 5.AB.25 | Huntite | CaMg3(CO3)4 |
| 5.AB.30 | Norsethite | BaMg(CO3)2 |
| 5.AB.35 | Alstonite | BaCa(CO3)2 |
| 5.AB.40 | Paralstonite | BaCa(CO3)2 |
| 5.AB.40 | Olekminskite | Sr(Sr,Ca,Ba)(CO3)2 |
| 5.AB.45 | Barytocalcite | BaCa(CO3)2 |
| 5.AB.50 | Carbocernaite | (Ca,Na)(Sr,Ce,Ba)(CO3)2 |
| 5.AB.60 | Juangodoyite | Na2Cu(CO3)2 |
Fluorescence of Benstonite
Red or yellow in SW-UV, LW-UV, or X-rays.
Red phosphorescence.
Red phosphorescence.
Other Information
Notes:
Soluble in HCl.
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 Benstonite
mindat.org URL:
https://www.mindat.org/min-626.html
Please feel free to link to this page.
Please feel free to link to this page.
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Mineral Dealers:
References for Benstonite
Reference List:
Lippmann, Friedrich (1961) Benstonit, Ca7Ba6(CO3)13, ein neues Mineral. Die Naturwissenschaften, 48 (16). 550-551 doi:10.1007/bf00639159
Lippmann, Friedrich (1961) Benstonit, Ca7Ba6(CO3)13, ein neues Mineral. Die Naturwissenschaften, 48 (16). 550-551 doi:10.1007/bf00639159
Lippmann, Friedrich (1962) Benstonite, Ca7Ba6(CO3)13, a new mineral from the barite deposit in Hot Spring County, Arkansas. American Mineralogist, 47 (5-6) 585-598
Localities for Benstonite
Showing 26 localities.
symbol to view information about a locality.
The Locality List
- 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).
All localities listed without proper references should be considered as questionable.
Canada | |
| Shang (2000) |
| Gardner et al. (1985) |
| Ansdell et al. (1989) | |
China | |
| Youbin Liang et al. (1981) |
Greece | |
| Skarpelis et al. (2004) |
India | |
| Semenov et al. (1971) +2 other references |
| Kumar et al. (2001) |
| Pavel M. Kartashov (n.d.) +1 other reference |
| Ramasamy et al. (2013) |
Italy | |
|
Minerva No. 1 Mine, Ozark-Mahoning group, Cave-In-Rock Mining Sub-District, Hardin County, Illinois, USA