  Cube under oil. 
This is a substantial cube of a relatively reactive rare earth (hence the "under oil" part).   
 
I chose this sample to represent its element in my Photographic Periodic Table Poster.  The sample photograph includes text exactly as it appears in the poster, which you are encouraged to buy a copy of. 
  
 
Source: David Franco 
Contributor: Ed Pegg Jr 
Acquired: 16 August, 2002 
Text Updated: 4 May, 2007 
Price: $43 
Size: 0.4" 
Purity: 99.99%
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