I just looked it up- apparently there are "synthetic slate tiles" too, & who knows what could be in those? Otherwise, it's just the weight issue- it might not be a good idea unless it's flat on the bottom of the enclosure- I don't think a snake could lift it & go under it. Setting it up on something would be dangerous unless it's firmly glued in place AND tip-proof. (And if this is in a glass tank, forget it! That's asking for it to be slid as a battering ram- lol.)