  Indium rod. 
This is very, very high purity indium, and the surface texture comes not from bending (as one might do to hear the crackling sound it makes) but rather from etching to show the crystal structure. 
Source: Juan Jimenez 
Contributor: Juan Jimenez 
Acquired: 2 December, 2007 
Text Updated: 7 December, 2007 
Price: Donated 
Size: 2.5" 
Purity: 99.99999%
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