Chris - really? I would assume because it is lighter in color that is it fine?? I have natural stone on my patio that is a bit darker than a typical travertine and it doesn't particularly get hot - even in St Louis crazy temps. Not to walk on - I would prob put a towel to lay on it in 102 degree temps we get here but never had a bare foot walking on it problem. maybe travertine "tile" gets hotter tho?

I'd be more worried about whether the natural inclusions in the stone would bother someone in terms of cleaning or something. at the end of the day tho you ARE outside...