[Calvin Locke]

Thorium is the #2 contributor to natural background radiation.

It used to be used in those Coleman lantern glass mantles.

[chrisser]

It used to be used in those Coleman lantern glass mantles.

I've always heard those were slightly radioactive. One of these days I'm going to get myself a Geiger counter.

I've often wondered why. Is the material they're made out of inherently radioactive or is the thorium added for some particular property it gives?