Downeyite

Locality: Burnside, Northumberland Co., Pennsylvania, USA

2 mm rock sample covered by very small white crystals of downeyite - natural selenium dioxide. The mineral is a coal-fire byproduct, formed by gas desublimation on a burning coal dump. The mineral is surprisingly unstable - its so extremely hygroscopic that decomposes in air in a very short time period and its probably connected with its structure degradation. The photo was taken through the plastic vial due to this mineral feature. The reddish areas are the ones where probably amorphous selenium occurs - it was possibly formed by downeyite decomposition. The specimen was obtained from Sonke Stolze mineral shop - thanks!

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Photo added: 15th Apr 2008

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Copyright © Jolyon Ralph and Ida Chau 1993-2012. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them. Further information contact the Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of hundreds of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register.
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