cheers nice oneI think slate is generally very good.
You'll want to give the thread some time to see if the experts have some other comments though.
Both flagstone and I believe, slate, used to be used routinely as the bottom plate for aquariums. Personally I liked that a lot better then the new way of using glass for the bottom. I think there was a lot less risk that flagstone (man-made slate I believe is what flagstone is, I should look it up!) would break.
~~waterdrop~~