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Burnside, Northumberland Co., Pennsylvania, USA
© Ł Kruszewski 08
|System:||Tetragonal||Colour:||Colourless (red - ...|
|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.
Classification of Downeyite
|IMA status:||Approved 1974|
|Strunz 8th edition ID:||4/D.14-20|
|Nickel-Strunz 10th (pending) edition ID:||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
|Dana 8th edition ID:||184.108.40.206|
4 : SIMPLE OXIDES
4 : AX2
|Hey's CIM Ref.:||7.17.1|
7 : Oxides and Hydroxides
17 : Oxides of Se and Te
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Type Occurrence of Downeyite
|Type Locality:||Forestville, Schuylkill Co., Pennsylvania, USA|
|General Appearance of Type Material:||Acicular to prismatic crystals|
|Place of Conservation of Type Material:||Smithsonian|
|Year of Discovery:||1971|
|Geological Setting of type material:||Burning anthracite culm banks|
Occurrences of Downeyite
|Geological Setting:||Burning coal banks.|
Physical Properties of Downeyite
|Colour:||Colourless (red - included selenium, yelllow - included sulfur)|
|Density (calculated):||4.146 g/cm3|
Crystallography of Downeyite
|Cell Parameters:||a = 8.36Å, c = 5.06Å|
|Ratio:||a:c = 1 : 0.605|
|Unit Cell Volume:||V 353.64 Å³ (Calculated from Unit Cell)|
|Morphology:||Acicular crystals to 2 cm.|
Optical Data of Downeyite
|Comments:||Extremely hygroscopic. In air will deliquesce in a few minutes and be absorbed into substrate or evaporate leaving colorless film.|
Chemical Properties of Downeyite
|Essential elements:||O, Se|
|All elements listed in formula:||O, Se|
Relationship of Downeyite to other Species
|Related Minerals - Nickel-Strunz Grouping):|
|Related Minerals - Hey's Index Grouping:|
Other Names for Downeyite
|Fluorescence in UV light:||None|
|Health Warning:||No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.|
References for Downeyite
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 Downeyite
Localities for Downeyite
The 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.
(TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
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