Real Uranium Glass!

I found some large uranium glass marbles for sale on ebay for a few dollars!  Above I am holding them under a blacklight for my first test of authenticity.  You can see them fluorescing chartreuse!  See my earlier blog post for this test with fake uranium glass. 

Next I hooked up our geiger counter.  In the picture above it recorded 414 counts per minute which is elevated well above the background rate. 

Above is a plot of the radiation level over time with the uranium glass, flanked by periods of background radiation.  It is plotted in units of micro-sievert per hour. 

Also, out of curiosity, I picked up a gas mantle that contains radioactive thorium and tested it. 

There was no noticeable increase in hits, which is not unexpected.  Thorium emits alpha particles which are stopped by the packaging (which I left on) and the glass of the GM detector tube.  However, there may be tiny amounts of beta emission from trace beta emitting thorium isotopes and elements in the decay series (thorium 232 decays to radium 228 with is a beta emitter).  Interestingly, thorium has a lot of properties that make it useful as a potential nuclear fuel source and research into thorium-based reactors is taking place (link). 

So, I had to try combining the uranium glass with the uranium ore to see how high I could get the CPM.

Here it is at 786 CPM or 6.4 µSv/h!  This was the highest spike, mostly it was around 4-5 µSv/h.  A CT scan is about 20 mSv, which corresponds to about 4000 hours (or 167 days, half a year) of exposure at this level.