Schists vary widely. Some are like soapstone and will work on a countertop if you are careful.

Did you look carefully at the edge of this stone? See if you can feel or see layers. If you can, I would avoid it.

Some of the metallic looking schists are very soft stones that are formed in layers which flake off. It depends on how much the stone has metamorphosed (been compressed) in the ground. I have schist in my bathroom and it is a catastrophe- I fell for the look and ignored the warnings about water. When water gets into these soft tiles they permanently change color and flake apart. The only way to protect them in this situation is with thick coats of sealer, which ruins the look and can be a problem itself if water finds its way under the sealer. These materials may work as a backsplash but should not be used on floors or counters.

Renee