Senegalite
A valid IMA mineral species
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About Senegalite
Flag of Senegal
Formula:
Al2(PO4)(OH)(OH)2 · H2O
Colour:
Colourless to light yellow, green
Lustre:
Vitreous
Hardness:
5½
Specific Gravity:
2.552
Crystal System:
Orthorhombic
Name:
Named in 1976 by Zdeněk Johan after its discovery locality, the iron deposit of Kouroudiako, located in the valley of Faleme, in eastern Senegal.
Type Locality:
This page provides mineralogical data about Senegalite.
Unique Identifiers
Mindat ID:
3619
Long-form identifier:
mindat:1:1:3619:7
IMA Classification of Senegalite
Classification of Senegalite
8.DE.05
8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
E : With only medium-sized cations, (OH, etc.):RO4 = 3:1
8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
E : With only medium-sized cations, (OH, etc.):RO4 = 3:1
42.6.7.1
42 : HYDRATED PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
6 : A2(XO4)Zq·xH2O
42 : HYDRATED PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
6 : A2(XO4)Zq·xH2O
19.7.4
19 : Phosphates
7 : Phosphates of Al alone
19 : Phosphates
7 : Phosphates of Al alone
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 |
|---|---|---|
| Sng | 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 Senegalite
Vitreous
Transparency:
Transparent
Colour:
Colourless to light yellow, green
Comment:
Fresh senegalite is green becoming yellow on exposure to sunlight.
Streak:
White
Hardness:
5½ on Mohs scale
Cleavage:
Poor/Indistinct
{010}, poor
{010}, poor
Density:
2.552(7) g/cm3 (Measured) 2.551 g/cm3 (Calculated)
Optical Data of Senegalite
Type:
Biaxial (+)
RI values:
nα = 1.562 nβ = 1.566 nγ = 1.587
2V:
Measured: 53° , Calculated: 48°
Max. Birefringence:
δ = 0.025
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:
Moderate (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:
strong
Optical Extinction:
Parallel. X = c; Y = a; Z = b.
Chemistry of Senegalite
Mindat Formula:
Al2(PO4)(OH)(OH)2 · H2O
Element Weights:
Elements listed:
Crystallography of Senegalite
Crystal System:
Orthorhombic
Class (H-M):
mm2 - Pyramidal
Cell Parameters:
a = 7.675(4) Å, b = 9.711(4) Å, c = 7.635(4) Å
Ratio:
a:b:c = 0.79 : 1 : 0.786
Unit Cell V:
569.05 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Flattened on [010], showing large {001}, {010},{101}, {111}, small {100}, {011}, {021}.
Comment:
SG P21nb (non-standard setting)
Crystal Structure
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Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
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Display Options
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2D | Stereo | Red-Blue | Red-Cyan
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View
CIF File Best | x | y | z | a | b | c
CIF File Best | x | y | z | a | b | c
Rotation
Stop | Start
Stop | Start
Labels
Console Off | On | Grey | Yellow
Console Off | On | Grey | Yellow
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) |
|---|---|---|---|---|---|---|---|
| 0000752 | Senegalite | Keegan T D, Araki T, Moore P B (1979) Senegalite, Al2(OH)3(H2O)(PO4), a novel structure type American Mineralogist 64 1243-1247 |  | 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 |
|---|---|
| 3.834 Å | (100) |
| 2.990 Å | (90) |
| 3.610 Å | (80) |
| 2.348 Å | (80) |
| 5.41 Å | (70) |
| 2.070 Å | (70) |
| 1.929 Å | (70) |
| 1.505 Å | (70) |
| 3.212 Å | (60) |
| 2.420 Å | (60) |
| 1.609 Å | (60) |
Comments:
Mount Kourou Diakouma, Senegal. The data are from the type description.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47c : [Carbonates, phosphates, borates, nitrates] |
Type Occurrence of Senegalite
General Appearance of Type Material:
Millimetric-sized crystals lining the walls of a boxwork, always covered with turquoise. Sometimes the senegalite fills the space.
Place of Conservation of Type Material:
National School of Mines, Paris, France.
Geological Setting of Type Material:
Oxidation zone of an iron ore deposit.
Associated Minerals at Type Locality:
Synonyms of Senegalite
Other Language Names for Senegalite
Common Associates
Associations Based on Photo Data:
| 149 photos of Senegalite associated with Turquoise | CuAl6(PO4)4(OH)8 · 4H2O |
| 24 photos of Senegalite associated with Crandallite | CaAl3(PO4)(PO3OH)(OH)6 |
| 8 photos of Senegalite associated with Augelite | Al2(PO4)(OH)3 |
| 1 photo of Senegalite associated with Variscite | AlPO4 · 2H2O |
| 1 photo of Senegalite associated with 'Limonite' |
Related Minerals - Strunz-mindat Grouping
| 8.DE. | Arsenoveszelyite | Cu2Zn(AsO4)(OH)3 · 2H2O |
| 8.DE. | Kipushite | (Cu,Zn)5Zn(PO4)2(OH)6 · H2O |
| 8.DE. | Goldhillite | Cu5Zn(AsO4)2(OH)6 · H2O |
| 8.DE.10 | Fluellite | Al2(PO4)F2(OH) · 7H2O |
| 8.DE.15 | Bulachite | Al6(AsO4)3(OH)9(H2O)4 · 2H2O |
| 8.DE.20 | Zapatalite | Cu3Al4(PO4)3(OH)9 · 4H2O |
| 8.DE.25 | Ceruleite | Cu2Al7(AsO4)4(OH)13 · 11.5H2O |
| 8.DE.30 | Veszelyite | (Cu,Zn)2Zn(PO4)(OH)3 · 2H2O |
| 8.DE.35 | Philipsburgite | Cu5Zn(AsO4)(PO4)(OH)6 · H2O |
| 8.DE.40 | Juanitaite | (Cu,Ca,Fe)10Bi(AsO4)4(OH)11 · 2H2O |
| 8.DE.45 | Iangreyite | Ca2Al7(PO4)2(PO3OH)2(OH,F)15 · 8H2O |
Fluorescence of Senegalite
Not fluorescent.
Other Information
IR Spectrum:
The IR spectrum indicates the presence of hydroxyl and H2O.
Special Storage/
Display Requirements:
Display Requirements:
Fades from green to yellow in sunlight. Keep out of Sunlight!
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 Senegalite
mindat.org URL:
https://www.mindat.org/min-3619.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 Senegalite
Reference List:
Johan, Zdenek (1976) La sénégalite, Al2(PO4) (OH)3 · H2O, un nouveau minéral. Lithos, 9 (2). 165-171 doi:10.1016/0024-4937(76)90034-7
Fleischer, Michael, Cabri, Louis J., Nickel, Ernest H., Pabst, Adolf (1977) New Mineral Names. American Mineralogist, 62 (5-6) 593-600
Keegan, Terry D., Araki, Takaharu, Moore, Paul B. (1979) Senegalite, Al2(OH)3(H2O)(PO4), a novel structure type. American Mineralogist, 64 (11-12) 1243-1247
Bleam, William F., Dec, Stephen F., Frye, James S. (1989) 27Al Solid-state nuclear magnetic resonance study of five-coordinate aluminum in augelite and senegalite. Physics and Chemistry of Minerals, 16 (8) 817-820 doi:10.1007/bf00209706
Localities for Senegalite
Showing 4 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.
Brazil | |
| Sioeira et al. (1982) |
| B Gioia collection +1 other reference |
| 531 p +6 other references |
Senegal (TL) | |
| Keegan et al. (1979) +1 other reference |
Quick NavTopAbout SenegaliteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography Crystal StructureX-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesCommon AssociatesStrunz-MindatFluorescence Other InformationInternet Links References Localities Locality List
Mount Kourou Diakouma, Saraya, Kédougou Region, Senegal