Uranium Containing Marble (ca. 1960s)

Marbles. These sure do bring back memories. Marbles and trading cards, the coin and paper currency of my elementary school days. Times have probably changed.

Some of the old cats eye marbles, possibly other types as well, owed their yellow color to uranium. The marble to the left of the above photo has a sort of non-uniform milky interior. The fact that it does not fluoresce under the black light indicates that it probably does not contain uranium (photo above right). The cats-eye marble to the right of each photo contains uranium, as indicated by the fact that it fluoresces. Note that the activity of the uranium is far too low to be detectable with a simple survey meter.