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Downeyite

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Formula:
SeO2
Colour:
Colourless (red - included selenium, yelllow - included sulfur)
Lustre:
Adamantine
Specific Gravity:
4.146 (Calculated)
Crystal System:
Tetragonal
Name:
For Wayne F. Downey, Jr., who discovered the mineral. He was a high school student at the time.
Naturally occuring selenium(IV) oxide, extremely hygroscopic.


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Classification of DowneyiteHide

Approved
Approval Year:
1974
4.DE.05

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
E : With medium-sized cations; with various polyhedra
4.4.3.1

4 : SIMPLE OXIDES
4 : AX2
7.17.1

7 : Oxides and Hydroxides
17 : Oxides of Se and Te

Physical Properties of DowneyiteHide

Adamantine
Transparency:
Transparent
Colour:
Colourless (red - included selenium, yelllow - included sulfur)
Density:
4.146 g/cm3 (Calculated)

Optical Data of DowneyiteHide

Type:
Uniaxial (+)
Comments:
Extremely hygroscopic. In air will deliquesce in a few minutes and be absorbed into substrate or evaporate leaving colorless film.

Chemical Properties of DowneyiteHide

Formula:
SeO2

Crystallography of DowneyiteHide

Crystal System:
Tetragonal
Cell Parameters:
a = 8.36 Å, c = 5.06 Å
Ratio:
a:c = 1 : 0.605
Unit Cell V:
353.64 ų (Calculated from Unit Cell)
Morphology:
Acicular crystals to 2 cm.

Type Occurrence of DowneyiteHide

General Appearance of Type Material:
Acicular to prismatic crystals
Place of Conservation of Type Material:
Smithsonian
Geological Setting of Type Material:
Burning anthracite culm banks

Synonyms of DowneyiteHide

Other Language Names for DowneyiteHide

German:Downeyit
Spanish:Downeyita

Related Minerals - Nickel-Strunz GroupingHide

4.DE.10Koragoite(Mn2+,Fe3+)3(Nb,Ta,Ti)2(Nb,Mn)2(W,Ta)2O20Mon. 2 : P21
4.DE.15KoechliniteBi2MoO6Orth. mm2 : Pna21
4.DE.15RusselliteBi2WO6Orth.
4.DE.15TungstibiteSb3+2WO6Orth. 2 2 2
4.DE.20TelluriteTeO2Orth. mmm (2/m 2/m 2/m)
4.DE.25ParatelluriteTeO2Tet.
4.DE.30BismutotantaliteBi(Ta,Nb)O4Orth.
4.DE.30BismutocolumbiteBi(Nb,Ta)O4Orth. mmm (2/m 2/m 2/m)
4.DE.30CervantiteSb3+Sb5+O4Orth.
4.DE.30StibiotantaliteSb(Ta,Nb)O4Orth. mm2
4.DE.30StibiocolumbiteSb(Nb,Ta)O4Orth. mm2
4.DE.30ClinocervantiteSb3+Sb5+O4Mon.
4.DE.35BaddeleyiteZrO2Mon. 2/m : P21/b

Related Minerals - Dana Grouping (8th Ed.)Hide

4.4.3.2ParatelluriteTeO2Tet.

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

7.17.2TelluriteTeO2Orth. mmm (2/m 2/m 2/m)
7.17.3ParatelluriteTeO2Tet.
7.17.4ChiluiteBi3Te6+Mo6+O10.5Hex.

Fluorescence of DowneyiteHide

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 DowneyiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Finkelman, R. B. & Mrose, M. E. (1977): Downeyite, the first verified natural occurrence of selenium dioxide. American Mineralogist 62, 316-320.
Journal of the American Chemical Society: 59: 789-794.

Internet Links for DowneyiteHide

Localities for DowneyiteHide

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
 
  • Pennsylvania
    • Northumberland Co.
Mineralogy associated with burning Anthracite deposits of Eastern Pennsylvania, D. M. Lapham, J. H. Barns, W. Downey Jr. and R. B. Finkelman, Min. Rescs. Report #78, 1980
    • Schuylkill Co.
Finkelman, R.B. & Mrose, M.E. (1977) American Mineralogist: 62,316-320.
Mineral and/or Locality  
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