What is this rock? Safe for aquarium?

[Daven]

I bought this from an aquarium store.
It looks like some kind of sedimemtary layered rock or man made? But cannot identify it. It has like a sandy clay inbetween some of the layers, a few smaller bits snapped off like plaster others are hard as, well, rock. Was dusty prior to washing, no fibres though. Stinky. No idea what the bluey black part is either. Thanks.

 

[Billdogg]

yes, its a sedimentary rock, with what appears to be slate or shale as one of the layers. Although it would almost certainly be fine for a FW tank, I'd be very leery of putting it in a marine tank due to what may leech out over time.

 

[Daven]

Thank you! Thankfully in this instance I got it for a FW tank. Have a great weekend!