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Postite

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About PostiteHide

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
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.


Classification of PostiteHide

Approved
Approval Year:
2011

Physical Properties of PostiteHide

Sub-Adamantine
Transparency:
Transparent
Colour:
golden yellow
Streak:
yellow
Hardness:
Tenacity:
Brittle
Cleavage:
Perfect
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 PostiteHide

Type:
Biaxial (+)
RI values:
nα = 1.727(3) nβ = 1.733(3) nγ = 1.745(3)
2V:
Calculated: 71°
Max Birefringence:
δ = 0.018
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
High
Dispersion:
not observed
Pleochroism:
Non-pleochroic

Chemical Properties of PostiteHide

Formula:
Mg(H2O)6Al2(OH)2(H2O)8(V10O28)·13H2O
IMA Formula:
Mg(H2O)6Al2(OH)2(H2O)8(V10O28) · 13H2O

Crystallography of PostiteHide

Crystal System:
Orthorhombic
Class (H-M):
mmm (2/m 2/m 2/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

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
8.937(100)
12.190(90)
3.771(24)
8.248(22)

Type Occurrence of PostiteHide

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.

Synonyms of PostiteHide

Fluorescence of PostiteHide

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for PostiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Kampf, A.R., J.M. Hughes, J. Marty, and B. Nash (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. Canadian Mineralogist: 50(1): 45-53.
American Mineralogist (2014): 99: 2156-2157 (abstract).

Internet Links for PostiteHide

Localities for PostiteHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for 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). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
USA
 
  • Colorado
    • Mesa Co.
      • Gateway District
        • Gateway
Kampf, A.R., Nash, B.P., Marty, J., Hughes, J.M. (2016): Mesaite, CaMn2+5(V2O7)3·12H2O, a new vanadate mineral from the Packrat mine, near Gateway, Mesa County, Colorado, USA. Mineralogical Magazine: 80: (in press)
  • Utah
    • San Juan Co.
      • La Sal District (Paradox Valley District)
        • La Sal
Kampf, A.R., J.M. Hughes, J. Marty, and B. Nash (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. Canadian Mineralogist: 50(1): 45-53.
        • Lion Canyon
Collected By Chuck Adan, In the Collection of Alex Earl.
Kampf, A.R., J.M. Hughes, J. Marty, and B. Nash (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. Canadian Mineralogist: 50(1): 45-53.
Mineral and/or Locality  
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