Alforsite
A valid IMA mineral species
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About Alforsite
John T. Alfors
Formula:
Ba5(PO4)3Cl
Colour:
Colorless
Lustre:
Vitreous, Sub-Vitreous
Hardness:
5
Specific Gravity:
4.80 (Calculated)
Crystal System:
Hexagonal
Member of:
Name:
Named by N. G. Newberry, Eric J. Essene, and Donald R. Peacor in honor of John T. Alfors [November 24, 1930 Reedley, CA, USA - December 27, 2005 Davis, CA], geologist and systematic mineralogist with the California geological Survey, USA.
Unique Identifiers
Mindat ID:
112
Long-form identifier:
mindat:1:1:112:0
IMA Classification of Alforsite
Approved
Approval year:
1980
Classification of Alforsite
8.BN.05
8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
N : With only large cations, (OH, etc.):RO4 = 0.33:1
8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
N : With only large cations, (OH, etc.):RO4 = 0.33:1
41.8.5.2
41 : ANHYDROUS PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
8 : A5(XO4)3Zq
41 : ANHYDROUS PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
8 : A5(XO4)3Zq
22.2.7
22 : Phosphates, Arsenates or Vanadates with other Anions
2 : Phosphates, arsenates or vanadates with chloride
22 : Phosphates, Arsenates or Vanadates with other Anions
2 : Phosphates, arsenates or vanadates with chloride
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 |
|---|---|---|
| Afr | 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 Alforsite
Vitreous, Sub-Vitreous
Transparency:
Transparent
Colour:
Colorless
Streak:
White
Hardness:
5 on Mohs scale
Tenacity:
Brittle
Cleavage:
None Observed
Density:
4.80 g/cm3 (Calculated)
Comment:
Also 4.73
Optical Data of Alforsite
Type:
Uniaxial (-)
RI values:
nω = 1.700 nε = 1.701
Birefringence:
0.001
Max. Birefringence:
δ = 0.001
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 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.
Optical Extinction:
Parallel
Pleochroism:
Non-pleochroic
Chemistry of Alforsite
Mindat Formula:
Ba5(PO4)3Cl
Element Weights:
Elements listed:
Crystallography of Alforsite
Crystal System:
Hexagonal
Class (H-M):
6/m - Dipyramidal
Space Group:
P63/m
Setting:
P63/m
Cell Parameters:
a = 10.25 Å, c = 7.64 Å
Ratio:
a:c = 1 : 0.745
Unit Cell V:
695.14 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Crystals are subhedral, to 0.2 mm, in very fine-grained masses.
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Show
Big Balls | Small Balls | Just Balls | Spacefill
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2D | Stereo | Red-Blue | Red-Cyan
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2D | Stereo | Red-Blue | Red-Cyan
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
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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) |
|---|---|---|---|---|---|---|---|
| 0009691 | Alforsite | Hata M, Marumo F, Iwai S, Aoki H (1979) Structure of barium chlorapatite Acta Crystallographica B35 2382-2384 |  | 1979 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.06 Å | (100) |
| 2.13 Å | (40) |
| 2.03 Å | (30) |
| 1.928 Å | (30) |
| 1.566 Å | (30) |
| 1.336 Å | (30) |
| 1.077 Å | (30) |
Comments:
Synthetic material
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 26 : Hadean detrital minerals | |
| Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
| 51 : Pyrometamorphic minerals (see also #54 and #56) | <0.36 |
Geological Setting:
In lenses and bands of barium silicate metasediments developed under hornblende-pyroxene hornfels facies near the contact with granite or granodiorite.
Type Occurrence of Alforsite
Co-Type Localities:
Place of Conservation of Type Material:
National Museum of Natural History, Washington, D.C., USA, 147511.
Geological Setting of Type Material:
Contact metamorphosed barium-rich metasediments
Associated Minerals at Type Locality:
Synonyms of Alforsite
Other Language Names for Alforsite
Relationship of Alforsite to other Species
Member of:
Other Members of Apatite Group:
| 'Apatite' | Ca5(PO4)3A | |
| Chlorapatite | Ca5(PO4)3Cl | Hex. 6/m : P63/m |
| Fluoralforsite | Ba5(PO4)3F | Hex. 6/m : P6/m |
| Fluorapatite | Ca5(PO4)3F | Hex. 6/m : P63/m |
| Fluorpyromorphite | Pb5(PO4)3F | Hex. 6/m : P63/m |
| Hydroxylapatite | Ca5(PO4)3(OH) | Hex. 6/m : P63/m |
| Hydroxylpyromorphite | Pb5(PO4)3(OH) | Hex. 6/mmm(6/m2/m2/m) : P63/mcm |
| Johnbaumite | Ca5(AsO4)3(OH) | Hex. 6/m : P63/m |
| Mimetite | Pb5(AsO4)3Cl | Hex. 6/m : P63/m |
| 'Oxypyromorphite' | Pb10(PO4)6O | |
| Pieczkaite | Mn5(PO4)3Cl | Hex. 6/m : P63/m |
| Pliniusite | Ca5(VO4)3F | Hex. 6/m : P63/m |
| Pyromorphite | Pb5(PO4)3Cl | Hex. 6/m : P63/m |
| Stronadelphite | Sr5(PO4)3F | Hex. 6/m : P63/m |
| Svabite | Ca5(AsO4)3F | Hex. 6/mmm(6/m2/m2/m) : P63/mmc |
| Turneaureite | Ca5(AsO4)3Cl | Hex. 6/m : P63/m |
| 'Unnamed (OH-analogue of Mimetite)' | Pb5(AsO4)3(OH) | Hex. 6/m : P63/m |
| Vanadinite | Pb5(VO4)3Cl | Hex. 6/m : P63/m |
Common Associates
Associations Based on Photo Data:
| 4 photos of Alforsite associated with Sanbornite | BaSi2O5 |
| 3 photos of Alforsite associated with Titantaramellite | Ba4(Ti,Fe3+,Fe2+,Mg)4(B2Si8O27)O2Clx |
| 3 photos of Alforsite associated with Quartz | SiO2 |
| 2 photos of Alforsite associated with Gillespite | BaFe2+Si4O10 |
| 1 photo of Alforsite associated with Anandite | (Ba,K)(Fe2+,Mg)3((Si,Al,Fe)4O10)(S,OH)2 |
| 1 photo of Alforsite associated with Celsian | Ba(Al2Si2O8) |
Related Minerals - Strunz-mindat Grouping
| 8.BN. | Fluoralforsite | Ba5(PO4)3F |
| 8.BN. | Aradite | BaCa6[(SiO4)(VO4)](VO4)2F |
| 8.BN. | Magganasite | CuFe3+3O(AsO4)3 |
| 8.BN. | Fluorpyromorphite | Pb5(PO4)3F |
| 8.BN. | Fluorsigaiite | Ca2Sr3(PO4)3F |
| 8.BN.05 | Pieczkaite | Mn5(PO4)3Cl |
| 8.BN.05 | Fluorapatite | Ca5(PO4)3F |
| 8.BN.05 | Fluorcaphite | SrCaCa3(PO4)3F |
| 8.BN.05 | Vanadinite | Pb5(VO4)3Cl |
| 8.BN.05 | Hedyphane | Ca2Pb3(AsO4)3Cl |
| 8.BN.05 | Hydroxylhedyphane | Ca2Pb3(AsO4)3(OH) |
| 8.BN.05 | 'Mimetite-M' | Pb5(AsO4)3Cl |
| 8.BN.05 | Johnbaumite | Ca5(AsO4)3(OH) |
| 8.BN.05 | Pliniusite | Ca5(VO4)3F |
| 8.BN.05 | 'Hydroxylapatite-M' | Ca5(PO4)3OH |
| 8.BN.05 | Hydroxylpyromorphite | Pb5(PO4)3(OH) |
| 8.BN.05 | Miyahisaite | (Sr,Ca)2Ba3(PO4)3F |
| 8.BN.05 | Carlgieseckeite-(Nd) | NaNdCa3(PO4)3F |
| 8.BN.05 | Belovite-(Ce) | NaCeSr3(PO4)3F |
| 8.BN.05 | Kuannersuite-(Ce) | NaCeBa3(PO4)3F0.5Cl0.5 |
| 8.BN.05 | 'Unnamed (OH-analogue of Mimetite)' | Pb5(AsO4)3(OH) |
| 8.BN.05 | Stronadelphite | Sr5(PO4)3F |
| 8.BN.05 | Parafiniukite | Ca2Mn3(PO4)3Cl |
| 8.BN.05 | Mimetite | Pb5(AsO4)3Cl |
| 8.BN.05 va | 'Germanate-pyromorphite' | Pb5(PO4)2GeO4 |
| 8.BN.05 | Belovite-(La) | NaLaSr3(PO4)3F |
| 8.BN.05 | Fluorphosphohedyphane | Ca2Pb3(PO4)3F |
| 8.BN.05 | Fluorstrophite | SrCaSr3(PO4)3F |
| 8.BN.05 | Hydroxylapatite | Ca5(PO4)3(OH) |
| 8.BN.05 | 'Johnbaumite-M' | Ca5(AsO4)3OH |
| 8.BN.05 | Phosphohedyphane | Ca2Pb3(PO4)3Cl |
| 8.BN.05 | Turneaureite | Ca5(AsO4)3Cl |
| 8.BN.05 | Morelandite | Ca2Ba3(AsO4)3Cl |
| 8.BN.05 | 'Oxypyromorphite' | Pb10(PO4)6O |
| 8.BN.05 | Deloneite | (Na0.5REE0.25Ca0.25)(Ca0.75REE0.25)Sr1.5(CaNa0.25REE0.25)(PO4)3F0.5(OH)0.5 |
| 8.BN.05 | Chlorapatite | Ca5(PO4)3Cl |
| 8.BN.05 | Pyromorphite | Pb5(PO4)3Cl |
| 8.BN.05 | Vanackerite | Pb4Cd(AsO4)3Cl |
| 8.BN.05 | Svabite | Ca5(AsO4)3F |
| 8.BN.10 | Arctite | Na2Ca4(PO4)3F |
| 8.BN.10 | Krügerite | BaCa6(SiO4)2[(P0.5S0.5)O4]2F |
| 8.BN.15 | Goryainovite | Ca2(PO4)Cl |
Fluorescence of Alforsite
Not fluorescent, but bright purple/violet cathodluminescence
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 Alforsite
mindat.org URL:
https://www.mindat.org/min-112.html
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References for Alforsite
Localities for Alforsite
Showing 11 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 | |
| McNeil et al. (2013) |
Germany | |
| Juroszek et al. (Ti 5 Fe) |
| Skrzyńska et al. (2023) | |
Israel | |
| Juroszek et al. (2025) |
| Krzątała et al. (2020) | |
| Krzątała et al. (2023) | |
Mexico | |
| Alfors et al. (1984) +2 other references |
USA (TL) | |
| Pemberton (1983) +1 other reference |
| Newberry et al. (1981) +1 other reference |
| Newberry et al. (1981) +3 other references |
| Dunning et al. (2003) |
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Esquire No. 7 claim, Big Creek, Big Creek-Rush Creek Mining District, Fresno County, California, USA