In short simple terms, the phrase "black slate" refers to a dark-colored rock that can be written on with chalk or other writing tools. Full definition
Black slate lines the floors and shower and contrasts with the industrial stainless - steel vanity. (westinny.com)
The richness of the wood is echoed in the shelving and window frames, while the sleek black slate floor gives the space a modern edge. (idealhome.co.uk)
Wood - burning stove A new wood - burning stove and decorating with black slate tiles look like they could be an original feature. (styleathome.com)