Andy Goldsworthy

Andy Goldsworthy uses natural materials and found objects exclusively in his work in surprising ways. Many of his works also focus on geometric patterns and forms. His use of contrast and color creates absolutely striking pieces. In this work he has collected river stones and arranged them according to their value on the grey scale with the lightest at the center and the darkest around the edge. the light stones contrast with the pitch black center - I wonder what material he used for that dark, pure black.