Shale in aquarium

[Sean_Buckley]

Would shale be ok in an aquarium? Or what?
Sean

 

[canarsie11]

Test it like any other rock

 

[fishdudein]

Any shale I have ever run across has been too crumbly(soft) and/or porous. Slate, which at first glance looks very similar to shale, is excellent for aquarium use, so that's what I would go with.