This rock is one of the oldest in the world at around two to three billion years old. It is found on the north west coast and islands of Scotland. It can be seen in small pebbles on the beach or across the face of exposed cliffs. It has these characteristic swirling black grey and white lines that loop and swirl within the rock. I have spent the last seven years perfecting this particular finish in naked raku on my vessels. I love it that they look not like clay but actually like the stone I am imitating.