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Postite
A valid IMA mineral species
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About Postite
Jeffrey Post
Formula:
Mg(H2O)6Al2(OH)2(H2O)8(V10O28) · 13H2O
Colour:
golden yellow
Lustre:
Sub-Adamantine
Hardness:
2
Specific Gravity:
2.226 (Calculated)
Crystal System:
Orthorhombic
Member of:
Name:
Named in honor of Dr. Jeffrey E. Post (b.1954), mineralogist and curator of the Smithsonian Institution mineral and gem collections.
This page provides mineralogical data about Postite.
Unique Identifiers
Mindat ID:
42268
Long-form identifier:
mindat:1:1:42268:8
Similar Names
Classification of Postite
The Decavanadate Cluster
The decavanadate cluster found in postite. The same cluster is known in a number of other secondary vanadium minerals including, for example, pascoite, hummerite, and rakovanite.
IMA Classification of Postite
Approved
IMA Formula:
MgAl2(OH)2[V5+10O28]·27H2O
Approval year:
2011
First published:
2012
Type description reference:
4.HC.55
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
H : V[5,6] Vanadates
C : [6]-Sorovanadates
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
H : V[5,6] Vanadates
C : [6]-Sorovanadates
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 |
|---|---|---|
| Pos | 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 Postite
Sub-Adamantine
Transparency:
Transparent
Colour:
Golden yellow
Streak:
Yellow
Hardness:
2 on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
one good cleavage on {001} and at least two perfect cleavages parallel to [001], possibly on {100} and {010}
one good cleavage on {001} and at least two perfect cleavages parallel to [001], possibly on {100} and {010}
Parting:
none
Fracture:
Splintery
Density:
2.226 g/cm3 (Calculated)
Comment:
density of postite could not be measured because the mineral dissolves in an aqueous sodium polytungstate solution
Optical Data of Postite
Type:
Biaxial (+)
RI values:
nα = 1.727(3) nβ = 1.733(3) nγ = 1.745(3)
2V:
Calculated: 71°
Max. Birefringence:
δ = 0.018
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:
not observed
Pleochroism:
Non-pleochroic
Chemistry of Postite
Mindat Formula:
Mg(H2O)6Al2(OH)2(H2O)8(V10O28) · 13H2O
Element Weights:
Crystallography of Postite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Space Group:
Pccn
Setting:
Pccn
Cell Parameters:
a = 16.3357(6) Å, b = 24.2434(17) Å, c = 11.7343(4) Å
Ratio:
a:b:c = 0.674 : 1 : 0.484
Unit Cell V:
4,647.17 ų (Calculated from Unit Cell)
Z:
4
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) |
|---|---|---|---|---|---|---|---|
| 0019040 | Postite | Kampf A R, Hughes J M, Marty J, Nash B (2012) Postite, Mg(H2O)6Al2(OH)2(H2O)8(V10O28)*13H2O, a new mineral species from the La Sal Mining District, Utah: Crystal structure and descriptive mineralogy The Canadian Mineralogist 50 45-53 | 2012 | La Sal Mining District, Utah, USA | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 8.937 Å | (100) |
| 12.190 Å | (90) |
| 3.771 Å | (24) |
| 8.248 Å | (22) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47e : [Vanadates, chromates, manganates] | |
| Stage 10b: Anthropogenic minerals | <10 Ka |
| 55 : Anthropogenic mine minerals |
Type Occurrence of Postite
Co-Type Localities:
General Appearance of Type Material:
very thin, needle-like prisms with pyramidal terminations; some needles are slightly curved. Crystals generally occur in parallel bundles and grow in divergent and “jackstraw” masses. Individual crystals are up to 1 mm long and 50 µm in diameter.
Place of Conservation of Type Material:
Natural History Museum of Los Angeles County under catalogue numbers 63564 (Vanadium Queen mine) and 63563 (Blue Cap mine).
Geological Setting of Type Material:
forms from the oxidation of montroseite-corvusite assemblages in a moist environment.
Associated Minerals at Type Locality:
Synonyms of Postite
Other Language Names for Postite
Relationship of Postite to other Species
Member of:
Other Members of Pascoite Family:
| Ammoniolasalite | [(NH4)2Mg2(H2O)20] [V10O28] | Mon. 2/m : B2/b |
| Bluestreakite | K4Mg2(V4+2V5+8O28) · 14H2O | Mon. 2/m : P21/c |
| Burroite | Ca2(NH4)2(V10O28) · 15H2O | Tric. 1 : P1 |
| Caseyite | [(V5+O2)Al10-x(OH)20-2x(H2O)18-2x]2[H2V4+V5+9O28][V5+10O28]2(Na,K,Ca)2-y(SO4)2-z · (60+8x+y+4z)H2O (x = 0-2.5; y = 0-2; z = 0-2) | Mon. 2/m : P21/c |
| Flatimerite | [Al13(OH)24(H2O)24][V5+9V4+O28] · [(SO4)4(H2O)24] | Tric. 1 : P1 |
| Gunterite | Na4Ca(V10O28) · 20H2O | Mon. 2/m : B2/m |
| Huemulite | Na4Mg(V10O28) · 24H2O | Tric. |
| Hughesite | Na3Al(V10O28) · 22H2O | Tric. 1 : P1 |
| Hummerite | K2Mg2(V10O28) · 16H2O | Tric. 1 : P1 |
| Hydropascoite | Ca3(V10O28) · 24H2O | Tric. 1 : P1 |
| Kokinosite | Na2Ca2(V10O28) · 24H2O | Tric. 1 : P1 |
| Lasalite | Na2Mg2(V10O28) · 20H2O | Mon. 2/m : B2/b |
| Magnesiopascoite | Ca2Mg(V10O28) · 16H2O | Mon. 2/m : B2/m |
| Nashite | Na3Ca2[(V5+9V4+)O28] · 24H2O | Mon. 2/m : P21/m |
| Okieite | Mg3[V10O28] · 28H2O | Tric. 1 : P1 |
| Pascoite | Ca2Ca(V10O28) · 17H2O | Mon. 2 : B2 |
| Protocaseyite | [Al4(OH)6(H2O)12][V10O28] · 8H2O | Tric. 1 : P1 |
| Rakovanite | (NH4)3Na3(V10O28) · 12H2O | Mon. 2/m : P21/c |
| Schindlerite | {(NH4)4Na2(H2O)10}{V10O28} | Tric. 1 : P1 |
| Trebiskyite | Na3Mg2[TiV9O28] · 22H2O | Mon. 2/m : P21/c |
| Wernerbaurite | {(NH4)2[Ca2(H2O)14](H2O)2}{V10O28} | Tric. 1 : P1 |
Common Associates
Associations Based on Photo Data:
| 2 photos of Postite associated with Montroseite | (V3+,Fe3+)O(OH) |
| 1 photo of Postite associated with Ammoniolasalite | [(NH4)2Mg2(H2O)20] [V10O28] |
| 1 photo of Postite associated with Corvusite | (Na,K,Ca,Mg)2(V5+,V4+,Fe2+)8O20 · 6-10H2O |
Related Minerals - Strunz-mindat Grouping
| 4.HC. | Protocaseyite | [Al4(OH)6(H2O)12][V10O28] · 8H2O |
| 4.HC. | Ammoniolasalite | [(NH4)2Mg2(H2O)20] [V10O28] |
| 4.HC. | Beckettite | Ca2V6Al6O20 |
| 4.HC. | Flatimerite | [Al13(OH)24(H2O)24][V5+9V4+O28] · [(SO4)4(H2O)24] |
| 4.HC.05 | Pascoite | Ca2Ca(V10O28) · 17H2O |
| 4.HC.05 | Hydropascoite | Ca3(V10O28) · 24H2O |
| 4.HC.05 | Lasalite | Na2Mg2(V10O28) · 20H2O |
| 4.HC.05 | Hughesite | Na3Al(V10O28) · 22H2O |
| 4.HC.05 | Magnesiopascoite | Ca2Mg(V10O28) · 16H2O |
| 4.HC.05 | Rakovanite | (NH4)3Na3(V10O28) · 12H2O |
| 4.HC.10 | Hummerite | K2Mg2(V10O28) · 16H2O |
| 4.HC.15 | Sherwoodite | Ca5.5(AlV4+V5+12O39) · 28H2O |
| 4.HC.20 | Bluestreakite | K4Mg2(V4+2V5+8O28) · 14H2O |
| 4.HC.25 | Wernerbaurite | {(NH4)2[Ca2(H2O)14](H2O)2}{V10O28} |
| 4.HC.25 | Burroite | Ca2(NH4)2(V10O28) · 15H2O |
| 4.HC.30 | Caseyite | [(V5+O2)Al10-x(OH)20-2x(H2O)18-2x]2[H2V4+V5+9O28][V5+10O28]2(Na,K,Ca)2-y(SO4)2-z · (60+8x+y+4z)H2O (x = 0-2.5; y = 0-2; z = 0-2) |
| 4.HC.35 | Gunterite | Na4Ca(V10O28) · 20H2O |
| 4.HC.40 | Kokinosite | Na2Ca2(V10O28) · 24H2O |
| 4.HC.45 | Nashite | Na3Ca2[(V5+9V4+)O28] · 24H2O |
| 4.HC.50 | Okieite | Mg3[V10O28] · 28H2O |
| 4.HC.60 | Schindlerite | {(NH4)4Na2(H2O)10}{V10O28} |
Fluorescence of Postite
none
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 Postite
mindat.org URL:
https://www.mindat.org/min-42268.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Postite
Reference List:
Kampf, A. R., Hughes, J. M., Marty, J., Nash, B. (2012) Postite, Mg(H2O)6Al2(OH)2(H2O)8(V10O28)·13H2O, a new mineral species from the La Sal District, Utah: Crystal structure and descriptive mineralogy. The Canadian Mineralogist, 50 (1) 45-53 doi:10.3749/canmin.50.1.45
Localities for Postite
Showing 8 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.
USA | |
| Carnegie Museum of Natural History ... |
| Kampf et al. (2017) | |
| Tony Kampf Identification |
| Collected by and in the collection of ... |
| Collected By Chuck Adan |
| Williams et al. (2011) +1 other reference |
| Williams et al. (2011) +1 other reference |
| Joe Marty Collection |
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Effie F. Mine, Polar Mesa, Gateway Mining District, Grand County, Utah, USA