Alfredopetrovite
A valid IMA mineral species
This page kindly sponsored by Mark Kucera
About Alfredopetrovite
Alfredo Petrov
Formula:
Al2(Se4+O3)3 · 6H2O
Colour:
Colorless
Lustre:
Sub-Vitreous
Hardness:
2½
Specific Gravity:
2.504 (Calculated)
Crystal System:
Hexagonal
Name:
To honor Alfredo Petrov, geologist, mineral dealer, translator, mineralogical travel guide in Bolivia and Japan, author of many publications on minerals and mineral localities.
A dimorph of bernardevansite.
In 2017, it was a new structure type and was at the time of approval a unique combination of elements (making it the first aluminium selenite mineral). Since then, as of 2025 the combination Al-Se-O has also been found in the minerals llantenesite, petermegawite and bernardevansite.
Structural details/elements:
- quite regular AlO6 octahedra
- SeO3 triangular pyramids
- [Al(H2O)3]2(SeO3)3 cluster formed by the connection of three selenate groups and two adjacent AlO6 octahedra
- hydrogen bonds, standing for the only linkage of the clusters
- relatively large channels running along [001].
The configuration of the above cluster resembles that of the distinctive unit in the NASICON-type structure, known as a lantern unit.
In 2017, it was a new structure type and was at the time of approval a unique combination of elements (making it the first aluminium selenite mineral). Since then, as of 2025 the combination Al-Se-O has also been found in the minerals llantenesite, petermegawite and bernardevansite.
Structural details/elements:
- quite regular AlO6 octahedra
- SeO3 triangular pyramids
- [Al(H2O)3]2(SeO3)3 cluster formed by the connection of three selenate groups and two adjacent AlO6 octahedra
- hydrogen bonds, standing for the only linkage of the clusters
- relatively large channels running along [001].
The configuration of the above cluster resembles that of the distinctive unit in the NASICON-type structure, known as a lantern unit.
Unique Identifiers
Mindat ID:
46683
Long-form identifier:
mindat:1:1:46683:1
IMA Classification of Alfredopetrovite
Approved
IMA Formula:
Al2(Se4+O3)3·6H2O
Approval year:
2015
First published:
2016
Classification of Alfredopetrovite
7.CA.X
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
C : Sulfates (selenates, etc.) without additional anions, with H2O
A : With small cations
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
C : Sulfates (selenates, etc.) without additional anions, with H2O
A : With small cations
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 |
|---|---|---|
| Afd | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Pronunciation of Alfredopetrovite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Alfredopetrovite
Sub-Vitreous
Transparency:
Translucent
Colour:
Colorless
Streak:
White
Hardness:
2½ on Mohs scale
Comment:
Based on scratch tests
Tenacity:
Brittle
Cleavage:
None Observed
Fracture:
Sub-Conchoidal
Comment:
Curved fracture
Density:
2.504 g/cm3 (Calculated)
Comment:
Could not be measured
Optical Data of Alfredopetrovite
Type:
Uniaxial (+)
RI values:
nω = 1.554(2) nε = 1.566(2)
Max. Birefringence:
δ = 0.012
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:
Low (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.
Pleochroism:
Non-pleochroic
Chemistry of Alfredopetrovite
Mindat Formula:
Al2(Se4+O3)3 · 6H2O
Element Weights:
Elements listed:
Crystallography of Alfredopetrovite
Crystal System:
Hexagonal
Class (H-M):
6m2 - Ditrigonal Dipyramidal
Space Group:
P62c
Setting:
P62c
Cell Parameters:
a = 8.818(3) Å, c = 10.721(2) Å
Ratio:
a:c = 1 : 1.216
Unit Cell V:
722 ų
Z:
2
Morphology:
No forms could be determined in type material because the crystals occur in intergrowths.
Twinning:
None observed.
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 7.63 Å | (55) |
| 6.22 Å | (55) |
| 5.37 Å | (26) |
| 4.398 Å | (40) |
| 3.404 Å | (100) |
| 2.783 Å | (50) |
| 2.606 Å | (22) |
| 1.661 Å | (26) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47d : [Arsenates, antimonates, selenates, bismuthinates] |
Type Occurrence of Alfredopetrovite
General Appearance of Type Material:
Drusy/scaly coatings and compact balls, the latter to 0.5 mm in diameter. Individual crystals are up to about 0.1 mm across.
Place of Conservation of Type Material:
Co-type material is deposited in the collections of the Natural History Museum of Los Angeles County, Los Angeles, USA, catalogue numbers 64111, 65578, 65579 and 65580, and the Museum Victoria, Australia, registration number M53004.
Geological Setting of Type Material:
Secondary phase in vugs within a selenide-dolomite-goethite matrix.
Associated Minerals at Type Locality:
Synonyms of Alfredopetrovite
Other Language Names for Alfredopetrovite
Dutch:Alfredopetroviet
French:Alfredopetrovite
German:Alfredopetrovit
Japanese:アルフレッドペトロヴ石
Norwegian:Alfredopetrovitt
Russian:Альфредопетровит
Spanish:Alfredopetrovita
Common Associates
Associations Based on Photo Data:
| 16 photos of Alfredopetrovite associated with Chalcomenite | CuSeO3 · 2H2O |
| 8 photos of Alfredopetrovite associated with Ahlfeldite | Ni(SeO3) · 2H2O |
| 5 photos of Alfredopetrovite associated with Kruťaite | CuSe2 |
| 4 photos of Alfredopetrovite associated with Felsőbányaite | Al4(SO4)(OH)10 · 4H2O |
| 2 photos of Alfredopetrovite associated with Penroseite | (Ni,Co,Cu)Se2 |
| 2 photos of Alfredopetrovite associated with Goethite | Fe3+O(OH) |
| 1 photo of Alfredopetrovite associated with Olsacherite | Pb2(Se6+O4)(SO4) |
| 1 photo of Alfredopetrovite associated with Clinochalcomenite | CuSeO3(H2O)2 |
| 1 photo of Alfredopetrovite associated with Umangite | Cu3Se2 |
Related Minerals - Strunz-mindat Grouping
| 7.CA. | Pilipenkoite | KCu(AsO4) · H2O |
Other Information
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 Alfredopetrovite
mindat.org URL:
https://www.mindat.org/min-46683.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 Alfredopetrovite
Reference List:
Hålenius, U., Hatert, F., Pasero, M., Mills, S. J. (2015) New minerals and nomenclature modifications approved in 2015, CNMNC Newsletter 26. Mineralogical Magazine, 79 (4) 941-947 doi:10.1180/minmag.2015.079.4.05
Localities for Alfredopetrovite
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) | |
| Hålenius et al. (2015) +2 other references |
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El Dragón mine, Porco Municipality, Antonio Quijarro Province, Potosí, Bolivia