The U.S. postage stamp honoring Sen. Brien McMahon and the Atomic Energy Act, issued in 1962, features a purple color and a denomination of 4 cents. This single stamp, of mint never hinged quality, in a protective sleeve,showcases the topic of atomic energy and is a collectible item originating from the United States. A special certification is not included with this stamp, making it a unique piece for those interested in U.S. postal history and atomic energy memorabilia.