Mineralium Deposita

, Volume 35, Issue 8, pp 796–798 | Cite as

The darkening of cinnabar in sunlight

  • J. K. McCormack
LETTER

Abstract

Most cinnabar is brilliant red and remains so under sunlight. However, some cinnabar is photosensitive and irreversibly blackens during exposure to sunlight. Electron microprobe analyses of cinnabar from several occurrences show that photosensitive cinnabar contains noteworthy concentrations of chlorine, whereas non-photosensitive cinnabar does not. Experimental evidence shows that non-photosensitive cinnabar becomes photosensitive after exposure to halogens. The darkening of cinnabar in sunlight is caused by the presence of contained chlorine or other halogens.

Keywords

Chlorine Experimental Evidence Halogen Electron Microprobe Microprobe Analysis 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2000

Authors and Affiliations

  • J. K. McCormack
    • 1
  1. 1.Department of Geological Sciences, MS 172, Mackay School of Mines, University of Nevada, Reno, Nevada 89557, USA e-mail: mccormac@mines.unr.edu Tel.: +1-775-7844518; Fax: +1-775-7841833US

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