It’s volcanic tuff stone deposited in seawater, below the wave beach area. Deposit has sedimentary structures, often emphasized by the fine grey/ green clays dispersed throughout the stone. Chloritic cement is common and it gives the grey/greenish colour , strongly visible under water. Stone must be installed with good circulation and filtering of the water (especially salt water) required to prevent brown algae forming. Chlorite being part of the stone confirms its resistance against chlorine. This stone is very porous, so it needs proper installation in swimming pools using cement-glues for swimming pools. If used in bathrooms we do recommend to use a good quality sealer to maintain the gloss of the stone tiles. It’s an unique stone, with a very special colour and wave pattern.