> I just want to repeat your last line, John:
> "I would be careful about rocks that might 'crack apart violently' when
heated."
>
> Don't ask me how I know this, but it has to do with a campfire and rocks
around
> the edge, and a much larger fire than the rock ring was intended for.

LOL, same here. Being involved in Scouts for 15 years taught me a few useful
things about fire; this is one of them. Another: both mosquito repellent and
aluminum burn well.

-John O