  Electrodes. 
I got these tantalum electrodes on eBay.  How do I know they are really tantalum?  Because I trust in the basic goodness of the eBay community and have no doubt that every item is exactly what it's claimed to be, especially the elements. 
Source: eBay seller snooj 
Contributor: Theodore Gray 
Acquired: 22 August, 2002 
Price: $10 
Size: 0.2" 
Purity: >90%
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