quarry tile

noun1

1. •
   A very hard ceramic tile used e.g. as flooring, usually 1/2 to 3/4 inches (13 to 19 mm) in thickness, made by the extrusion process from natural clays or shales.

   • The public areas have blue quarry-tile floors, pale blue glass mosaic walls and pillars and varnished timber ceilings; [...]. — 1960