Log In
Bernardevansite
A valid IMA mineral species
This page is currently not sponsored. Click here to sponsor this page.
About Bernardevansite
Bernard W. Evans
Formula:
Al2(SeO3)3 · 6H2O
Colour:
Colourless
Lustre:
Vitreous
Hardness:
2 - 3
Specific Gravity:
2.93
Crystal System:
Monoclinic
Name:
Named in honor of Dr Bernard W. Evans (b. 1934), Emeritus Professor in Mineralogy and Petrology at the University of Washington in Seattle, Washington, USA. He made significant contributions to the crystal chemistry and thermodynamics of amphiboles and metamorphic minerals. He has received numerous awards including the Roebling Medal of MSA (2008).
Isostructural with:
Unique Identifiers
Mindat ID:
470483
Long-form identifier:
mindat:1:1:470483:2
IMA Classification of Bernardevansite
Approved
IMA Formula:
Al2(Se4+O3)3·6H2O
Approval year:
2022
First published:
2023
Type description reference:
Yang, Hexiong, Gu, Xiangping, Jenkins, Robert A., Gibbs, Ronald B., Downs, Robert T. (2023) Bernardevansite, Al2(Se4+O3)3⋅6H2O, dimorphous with alfredopetrovite and the Al-analogue of mandarinoite, from the El Dragón mine, Potosí, Bolivia. Mineralogical Magazine, 87 (3) 407-414 doi:10.1180/mgm.2023.7
Classification of Bernardevansite
4.JH.
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
J : Arsenites, antimonites, bismuthites, sulfites, selenites, tellurites; iodates
H : Selenites without additional anions, with H2O
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
J : Arsenites, antimonites, bismuthites, sulfites, selenites, tellurites; iodates
H : Selenites without additional anions, with H2O
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 |
|---|---|---|
| Bev | 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 Bernardevansite
Vitreous
Transparency:
Transparent
Colour:
Colourless
Streak:
White
Hardness:
2 - 3 on Mohs scale
Tenacity:
Brittle
Cleavage:
None Observed
Density:
2.93(5) g/cm3 (Measured) 2.997 g/cm3 (Calculated)
Optical Data of Bernardevansite
Type:
Biaxial (+)
RI values:
nα = 1.642(5) nβ = 1.686(5) nγ = 1.74(1)
2V:
Measured: 84° (2), Calculated: 87°
Max. Birefringence:
δ = 0.098
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:
Very 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 biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Dispersion:
None observed.
Pleochroism:
Weak
Comments:
Very weak, from pale grey to grey.
Chemistry of Bernardevansite
Mindat Formula:
Al2(SeO3)3 · 6H2O
Element Weights:
Elements listed:
Chemical Analysis
Empirical formulas:
| Sample ID | Empirical Formula |
|---|---|
| 1 | (Al1.26Fe3+0.82)?2.08(Se0.98O3)3.6H2O |
Sample references:
| ID | Locality | Reference | Notes |
|---|---|---|---|
| 1 | El Dragón mine, Porco Municipality, Antonio Quijarro Province, Potosí, Bolivia | empirical formula basis: 15 O apfu |
Crystallography of Bernardevansite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/c
Setting:
P21/c
Cell Parameters:
a = 16.5016(5) Å, b = 7.7703(2) Å, c = 9.8524(3) Å
β = 98.258(3)°
β = 98.258(3)°
Ratio:
a:b:c = 2.124 : 1 : 1.268
Unit Cell V:
1,250.20 ų (Calculated from Unit Cell)
Morphology:
Aggregates or spheres of radiating bladed crystals. Individual crystals are elongated on [001] and forms include {100}, {110}, {110} and {001}.
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 8.147 Å | (39) |
| 7.036 Å | (100) |
| 3.515 Å | (64) |
| 3.385 Å | (47) |
| 3.013 Å | (29) |
| 2.943 Å | (80) |
| 2.769 Å | (37) |
| 2.247 Å | (20) |
Reference:
Yang, Hexiong, Gu, Xiangping, Jenkins, Robert A., Gibbs, Ronald B., Downs, Robert T. (2023) Bernardevansite, Al2(Se4+O3)3⋅6H2O, dimorphous with alfredopetrovite and the Al-analogue of mandarinoite, from the El Dragón mine, Potosí, Bolivia. Mineralogical Magazine, 87 (3) 407-414 doi:10.1180/mgm.2023.7
Comments:
El Dragón mine, Potosí, Bolivia. Data from the type description.
Type Occurrence of Bernardevansite
General Appearance of Type Material:
Aggregates or spheres comprising radiating, bladed crystals, on a matrix of Co-bearing krut’aite–penroseite.
Place of Conservation of Type Material:
Type material is deposited in the collections of the University of Arizona Alfie Norville Gem & Mineral Museum, 115 N Church Ave Ste 121, Tucson, AZ 85701, USA, catalogue number 22712 (holotype), and the RRUFF Project, deposition number R210010 (cotype).
Geological Setting of Type Material:
Weathered Se ore.
Associated Minerals at Type Locality:
Reference:
Yang, Hexiong, Gu, Xiangping, Jenkins, Robert A., Gibbs, Ronald B., Downs, Robert T. (2023) Bernardevansite, Al2(Se4+O3)3⋅6H2O, dimorphous with alfredopetrovite and the Al-analogue of mandarinoite, from the El Dragón mine, Potosí, Bolivia. Mineralogical Magazine, 87 (3) 407-414 doi:10.1180/mgm.2023.7
Synonyms of Bernardevansite
Other Language Names for Bernardevansite
Dutch:Bernardevansiet
German:Bernardevansit
Related Minerals - Strunz-mindat Grouping
| 4.JH. | Magselite | [Mg(H2O)6](Se4+O3) |
| 4.JH.05 | Chalcomenite | CuSeO3 · 2H2O |
| 4.JH.10 | Clinochalcomenite | CuSeO3(H2O)2 |
| 4.JH.10 | Ahlfeldite | Ni(SeO3) · 2H2O |
| 4.JH.10 | Cobaltomenite | CoSeO3 · 2H2O |
| 4.JH.15 | Mandarinoite | Fe3+2(Se4+O3)3 · (6-x)H2O (x = 0.0-1.0) |
| 4.JH.20 | Orlandiite | Pb3(SeO3)(Cl,OH)4 · H2O |
| 4.JH.30 | Nestolaite | CaSeO3 · H2O |
Other Information
Notes:
Insoluble in water or hydrochloric acid.
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 Bernardevansite
mindat.org URL:
https://www.mindat.org/min-470483.html
Please feel free to link to this page.
Please feel free to link to this page.
Search Engines:
External Links:
Mineral Dealers:
References for Bernardevansite
Reference List:
Miyawaki, Ritsuro, Hatert, Frédéric, Pasero, Marco, Mills, Stuart J. (2022) IMA Commission on New Minerals, Nomenclature and Classification (CNMNC) – Newsletter 70. European Journal of Mineralogy, 34 (6) 591-601 doi:10.5194/ejm-34-591-2022
Yang, Hexiong, Gu, Xiangping, Jenkins, Robert A., Gibbs, Ronald B., Downs, Robert T. (2023) Bernardevansite, Al2(Se4+O3)3⋅6H2O, dimorphous with alfredopetrovite and the Al-analogue of mandarinoite, from the El Dragón mine, Potosí, Bolivia. Mineralogical Magazine, 87 (3) 407-414 doi:10.1180/mgm.2023.7
Localities for Bernardevansite
Showing 1 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.
Bolivia (TL) | |
| Miyawaki et al. (2022) +1 other reference |
Quick NavTopAbout BernardevansiteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Chemical AnalysisCrystallography X-Ray Powder DiffractionType Occurrence SynonymsOther LanguagesStrunz-MindatOther InformationInternet Links References Localities Locality List
El Dragón mine, Porco Municipality, Antonio Quijarro Province, Potosí, Bolivia