Tube of uranium ore. 
This ore is from an old "ATOMIC ENERGY" chemistry set sold by Chemcraft in the 1950's. Radioactivity was popular back then.   
 
I got the chemistry set on eBay after consulting this trusty reference book about radioactive collectables.  According to its table of going rates for these things, I got a good deal on the chemistry set, though it is not in perfect condition and is missing some components.  Modern chemistry sets are pretty wimpy, but I have to say that, aside from the uranium ore and the radium, this set is pretty tame as well.  It even proudly claims to contain "no dangerous or explosive chemicals".  I mean really, where's the fun in that?  Here's a picture of the set: 
  
 
Source: eBay seller 6tomcat 
Contributor: Theodore Gray 
Acquired: 10 January, 2003 
Price: $58/chemistry set 
Size: 1" 
Purity: <1%
 |  
  |  
 |  
  |