Bahianite
A valid IMA mineral species
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About Bahianite
Flag of Bahia, Brazil
Formula:
Al5Sb3O14(OH)2
Colour:
Tan, cream, orange-brown, brown; crystals colourless, tan, pale violet; yellow internal reflections in transmitted light
Lustre:
Adamantine
Hardness:
9
Specific Gravity:
4.78 - 5.46
Crystal System:
Monoclinic
Name:
The name refers to the State of Bahia, Brazil, from within which state the initial specimens were found.
Currently the only known purely aluminium antimonate mineral. Structurally related to simpsonite.
The structure is unique and is based on hcp (hexagonal close packed) arrange of oxygen atoms, the set being parallel to {001}. There are layers consisting of edge-sharing Al5O14(OH)2 sheets, that corner-link to linear trimers of the Sb3O1413- composition.
The structure is unique and is based on hcp (hexagonal close packed) arrange of oxygen atoms, the set being parallel to {001}. There are layers consisting of edge-sharing Al5O14(OH)2 sheets, that corner-link to linear trimers of the Sb3O1413- composition.
Unique Identifiers
Mindat ID:
484
Long-form identifier:
mindat:1:1:484:4
GUID
(UUID V4):
(UUID V4):
94abce8d-1411-49c8-9939-7ffa20b0ed6e
IMA Classification of Bahianite
Approved
IMA Formula:
Al5Sb5+3O14(OH)2
Classification of Bahianite
4.DC.05
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
C : With medium-sized cations; sheets of edge-sharing octahedra
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
C : With medium-sized cations; sheets of edge-sharing octahedra
44.3.7.1
44 : ANTIMONATES
3 : Miscellaneous
44 : ANTIMONATES
3 : Miscellaneous
7.13.7
7 : Oxides and Hydroxides
13 : Oxides of As, Sb and Bi
7 : Oxides and Hydroxides
13 : Oxides of As, Sb and Bi
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 |
|---|---|---|
| Bhi | 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 Bahianite
Adamantine
Transparency:
Transparent, Translucent
Colour:
Tan, cream, orange-brown, brown; crystals colourless, tan, pale violet; yellow internal reflections in transmitted light
Hardness:
9 on Mohs scale
Hardness:
VHN100=1605 kg/mm2 - Vickers
Cleavage:
Perfect
on {100}
on {100}
Fracture:
Irregular/Uneven
Density:
4.78 - 5.46 g/cm3 (Measured) 5.26 g/cm3 (Calculated)
Optical Data of Bahianite
Type:
Biaxial (-)
RI values:
nα = 1.810 nβ = 1.870 nγ = 1.920
Max Birefringence:
δ = 0.110
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
Very High
Dispersion:
r > v
Pleochroism:
Weak
Chemistry of Bahianite
Mindat Formula:
Al5Sb3O14(OH)2
Elements listed:
Crystallography of Bahianite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/m
Setting:
C2/m
Cell Parameters:
a = 9.406 Å, b = 11.541 Å, c = 4.41 Å
β = 90.94°
β = 90.94°
Ratio:
a:b:c = 0.815 : 1 : 0.382
Unit Cell V:
478.66 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Curved and striated crystals, diamond-shaped or rectangular
Twinning:
Pseudohexagonal multiple contact twins, chrysoberyl-like
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) |
|---|---|---|---|---|---|---|---|
| 0014703 | Bahianite | Moore P B, Araki T (1976) Bahianite, Al5Sb3O14(O,OH)2, a novel hexagonal close-packed oxide structure Neues Jahrbuch fur Mineralogie, Abhandlungen 126 113-125 | 1976 | Serra de Mangabeira, Bahia, Brazil | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.241 Å | (100) |
| 3.194 Å | (100) |
| 2.156 Å | (80) |
| 4.712 Å | (70) |
| 2.457 Å | (70) |
| 2.411 Å | (70) |
| 1.648 Å | (70) |
Comments:
Recorded on type material
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 26 : Hadean detrital minerals | |
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47d : [Arsenates, antimonates, selenates, bismuthinates] |
Type Occurrence of Bahianite
General Appearance of Type Material:
Water-worn, bean-shaped pebbles, to 10 cm, with polycrystalline or radial-fibrous structure; also as crystals, lining pockets in the pebbles
Place of Conservation of Type Material:
Harvard University, Cambridge, Massachusetts, USA (No. 119088);
National Museum of Natural History, Washington, D.C., USA (Nos. 133875, 135922)
National Museum of Natural History, Washington, D.C., USA (Nos. 133875, 135922)
Geological Setting of Type Material:
In potholes as stream-worn pebbles and as residual concentrates above weathered volcanic rock
Associated Minerals at Type Locality:
Synonyms of Bahianite
Other Language Names for Bahianite
Common Associates
Associated Minerals Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
| 4.DC.10 | Simpsonite | Al4Ta3O13(OH) |
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 Bahianite
mindat.org URL:
https://www.mindat.org/min-484.html
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References for Bahianite
Localities for Bahianite
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.
Brazil | |
| Jeannine and Jacques Cassedanne : "Présence d'eskolaite dans les alluvions stannifères de la Chapada Diamantina (Bahia-Brésil) |
| Anthony (1997) |
| Cassedanne (1985) |
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Pico das Almas river, Paramirim das Crioulas, Érico Cardoso, Bahia, Brazil