  Thorite.  
This is a lovely shiny crystal of thorite, a rare radioactive mineral, from Mt. Zagi, Pakistan.  The price reflects the rarity of this species more so than its beauty, though this one is really quite attractive. 
Source: eBay seller 4jdk 
Contributor: Theodore Gray 
Acquired: 25 September, 2005 
Price: $76 
Size: 0.5" 
Composition: (Th,U)SiO
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