Blue in colour; this is an effective mulch, drainage or concrete stone aggregate. The rock eventually fades from a deep blue to a light grey after it has been exposed to the sun.

Most commonly used in concrete construction and is famous for its drainage abilities, making it ideal for conserving water in garden beds. Also used for erosion control and water-sealing landscaping features, as well as pipe bedding and retaining walls. Being a hard stone, it is also very durable.