Does slate stain?

Slate is a very dense metamorphic rock. Because it is not terribly porous, it cannot be easily stained. However, despite its density, slate tends to be soft and therefore is susceptible to liquid stains, particularly oil-based ones, but even water can soak into the stone and do damage. Therefore, it is recommended that slate be sealed with a non-glossy sealant that does not rob the stone of its natural beauty. If materials are spilled on slate, they should be cleaned up immediately to prevent any damage.