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UM1990-24-O:Al

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Formula:
σ-Al2O3
Co-described with UM1990-23-O:Al. Primarily though to be the δ phase. Probably not identical to deltalumite (most of the PXRD line positions differ).

Also associated with corundum.

The association is found as polycrystalline spherules, ca. 0.1 mm in diameter; they stand for 2-3% of a heavy fraction of minerals separated from loam and sandy loam (Upper Pleistocene to Holocene age) in different locations. of Yakutiya, USSR. The aluminous spherules are confined to layers, connected with formation of cryogenic soils. These metastable alumina polymorphs are though to be formed due to dehydration of colloidal aluminum hydroxides at subfreezing temperatures in the presence of saline pore solutions. They come from natural exposures within an uninhabitated area.


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Classification of UM1990-24-O:AlHide

Notes:
Unnamed (probably valid)

Chemical Properties of UM1990-24-O:AlHide

Formula:
σ-Al2O3

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
2.76(20)
2.59(10)
2.43(30)
2.30(20)
2.11(10)
2.01(30)
1.96(20)
1.52(10)
1.39(100)
Comments:
weak and diffuse lines; the most intense line coincides with the corresponding one of deltalumite's pattern

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 UM1990-24-O:AlHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Siegert, Ch., Shirokov, A.L., Nikishova, L.V., Pavlova, L.A., Babiy, O.A. (1990) Natural analogues of the alumina modifications (θ-Al2O3, and δ-Al2O3) in permafrost area sediments. Doklady Akad. Nauk SSSR: 313: 689-692 (in Russian); in: Jambor, J.L., Grew, E.S. (1992): New mineral Names. American Mineralogist: 77: 210
Smith, D.G.W., Nickel, E.H. (2007): A System of Codification for Unnamed Minerals: Report of the SubCommittee for Unnamed Minerals of the IMA Commission on New Minerals, Nomenclature and Classification. Canadian Mineralogist: 45: 983-1055; http://nrmima.nrm.se (2016)

Internet Links for UM1990-24-O:AlHide

Localities for UM1990-24-O:AlHide

ⓘ - 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.
Russia
 
  • Sakha Republic (Yakutia)
Siegert, Ch., Shirokov, A.L., Nikishova, L.V., Pavlova, L.A., Babiy, O.A. (1990) Natural analogues of the alumina modifications (θ-Al2O3, and δ-Al2O3) in permafrost area sediments. Doklady Akad. Nauk SSSR: 313: 689-692 (in Russian); in: Jambor, J.L., Grew, E.S. (1992): New mineral Names. American Mineralogist: 77: 210
Mineral and/or Locality  
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