Table mostly built - slate/flagstone?

Mole351

So I'm mostly done building my table - just have question on the slate piece. I've done some research on this site and am worried that a) the slate will break, and b) the slate + feet will not be enough blockage of heat with the design I've used (nakedwhiz plan . Not to mention I can't seem to find the slate anywhere after calling around to different lawn service and landscaping companies...but that's on me - I'll keep searching til I do. Its too late to run the boards all the way across the bottom and place pavers or firebricks on top. If I can find 2 pieces of 18x24" slate to put in the inlay - would that be enough to not break (just sitting on 4 1x4's going across), and is it in danger of burning the wood since the bottom of the slate is already sitting lower than the top of the boards running across the bottom level?

Just being a worry-wart I guess...

Thanks

carolinakid

Mole the slate will be fine if it's about an inch thick. I used flagstone on my table and it works great. And cheaper!