Slate is a fine-grained, foliated,
homogeneous, metamorphic rock. Slate can be made into roofing
slates, also called roofing shingles. Slate tiles are often used
for interior and exterior flooring or wall cladding. Tiles are
installed and set on mortar and grouted along the edges. Sealants
are often used on tiles to improve durability and appearance,
increase stain resistance, reduce efflorescence, and increase or
reduce surface smoothness.