  Crude Oil.  
Very hard to get considering how much of the stuff trades hands every day.  Just try to buy less than a shipload of it.  This is semi-sweet crude from the Frontier Formation in Riverton, Wyoming, and dates to the late Cretaceous, about 65 million years ago.  The "sweetness" of crude refers to its sulfur content: The "light sweet crude" you hear about on the news whenever its price is particularly extreme is low-sulfur, low-viscosity crude considered particularly disarable for refining into gasoline.   
It actually does taste sweet, I'm told by people who probably haven't tasted it either. 
Source: eBay seller quartzpegmatite 
Contributor: Theodore Gray 
Acquired: 11 March, 2009 
Text Updated: 13 March, 2009 
Price: Donated 
Size: 1" 
Composition: CH2
 |  
  |  
 |  
  |