Volcanic grey stone and white limestone which can be split very well giving a very natural looking appearance. The split rock is cut into strips, which are fitted together into nice looking wall panels. The panels are interlocking, so there on the walls there is no visible joint. Material is free of lime and sulfide, so it’s not sensitive for damage by outside weather conditions. In full sunlight no protection is required, when installed in shady conditions, under trees for instance, water proofing is recommended