<a href="//commons.wikimedia.org/wiki/Plutonium" title="Plutonium">Plutonium</a> pyrophoricity (spontaneously burning in contact with air, causes it to glow like an ember).
Los Alamos National Laboratory
Attribution
Scanned from:<br><cite style="font-style:normal">Haschke, Thomas M.; Allen, Thomas H.; and Morales, Luis A. (2000). "<a rel="nofollow" class="external text" href="http://library.lanl.gov/cgi-bin/getfile?number26.htm">Surface and Corrosion Chemistry of Plutonium</a>". <i>Los Alamos Science</i> (26): 257.</cite>