  Nodules. 
I didn't really understand until recently where these nodules came from.  People in China are selling bunches of them, and they are very beautiful.  I thought they must be electrowinning nodules (built up by electroplating), considering how similar they look to the nickel and copper electrowinning nodules I have.  
 
Fortunately reader Eric Winter has kindly pointed me to this article which indicates they are probably vapor deposited in the "Pidgeon process". 
 
Source: eBay seller artgarden2005 
Contributor: Theodore Gray 
Acquired: 16 December, 2006 
Text Updated: 9 April, 2009 
Price: $10 
Size: 3" 
Purity: >90%
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