This is a beautiful sheet of 4 stamps, issued by Togo in 2011, commemorating the 50th anniversary of the death of famous French geologist Pierre Berthier. Also featured are the minerals Calcite on Amethyst, Malachite, Cuproadamite (Copper Zinc Arsenate Hydroxide), and Poldervaartite. The sheet is Post Office fresh, mint never hinged, and F/VF.