Four minerals - azurite, copper, variscite, and wulfenite - were unearthed by the Postal Service to be featured on this set of stamps. Azurite, named so because of its beautiful azure-blue color, and variscite, a semi-precious gemstone, are chiefly used in jewelry and other ornamental pieces. Copper has been one of man’s most useful metals for almost 5,000 years. In ancient times, the chief source of copper was found on the island of Cyprus, and it came to be known as Cyprian metal. Today, our name and symbol (Cu) for copper come from the word “cuprum” – the Roman name for Cyprian metal. Wulfenite is found in great quantities near Eastern Europe and South America. This yellow-orange mineral forms a crystallized structure, giving it a jagged appearance.