Limestone Description: Limestone is a type of sedimentary rock formed mainly from calcium carbonate. This is often as a result of the accumulation of shell, coral and algal matter. Natural limestone paving has a textured feel and a gently undulating surface, but without the riven texture found in sandstone. It is available in a selection of finishes:a natural finish with hand-chipped edges, an antique or tumbled finish where the surface and edges have been smoothed to create an aged appearance and a sawn finish where the surface is flat with a slip-resistant, sand-blasted surface and sawn edges. It is often produced in a calibrated thickness where the variation in thickness of the slab is kept to a minimum to aid the laying process. Its colours are far more consistent across each slab than sandstone. Limestone Colours: Limestone tends to come in three colours, buff/grey, steel blue and black/ dark grey. The darker black shades can gradually lighten with weathering, however sealing the paving will help retain the dark colouration.