CREHST Museum - Atomic Marbles
For decades the Hanford Nuclear Site near Richland made nearly all of the plutonium used in America's atomic bombs. Richland is proud of it. That's why its local science venue -- the CREHST Museum (Columbia River Exhibition of History, Science, and Technology) -- displays scale models of some of the site's most famous reactors, and why it sells "atomic marbles" in its gift shop.
Atomic marbles are made by lowering normal marbles into a tank with radioactive cobalt-60. Gamma radiation kicks the marbles' electrons into overdrive, changing their clear glass to a honey brown color (Hint for purchasers: the longer the exposure, the darker the marble). For years the museum sold the marbles out of a gumball machine; now it sells them in single packages with a limit of two per person. That isn't because the marbles are dangerously radioactive (they aren't), but because the museum doesn't want someone buying out its hard-to-get supply and then reselling them.