This is a beautiful sheet of 4 stamps, issued by Comoros Islands in 2010, displaying minerals. Featured on the stamps are the rock-forming mineral Corundum, the gemstone Ruby, Fluorine, ore mineral Cassiterite, Stilbite-Ca, zeolite mineral Mordenite, the silicate mineral Titanite, Quartz Amethyst, Olmiite, Apophyllite-KF (Fluorapophyllite), Cerussite white lead ore, Tourmaline crystal silicate mineral, Liddicoatite crystal, Aquamarine Beryl silicate mineral, Albite Plagioclase Feldspar, and the Topaz silicate mineral of aluminum & fluorine. The sheet is Post Office fresh, mint never hinged, and F/VF.