Pellets. 
These look like "green" pressed pellets meant to be arc-melted or sintered.  They are crumbly as if made of a powder that has been only weakly bonded (e.g. exposed to great pressure but not heated to the point where the particles actually fuse together). 
Source: eBay seller nebulousstars 
Contributor: Theodore Gray 
Acquired: 1 September, 2004 
Price: $12 
Size: 1" 
Purity: 99%
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