Slate comes in many variations. Most of which should not be used in a wet area such as a shower. They will delaminate. Black slate is a more silt based stone that will not come apart at the seams, so to speak.
If you pick a stone for the shower, just realize, it requires sealing on a regular schedule.
Ron
If you pick a stone for the shower, just realize, it requires sealing on a regular schedule.
Ron