A preliminary electron microscope study of fresh, unpolished fractured surfaces of 31 samples of limestone reveals features that correlate well with appearance under the optical microscope. Smooth, granual, acicular, and rhombohedral surfaces are recognizable; some are spongy in detail. Mysterious features are the presence of tiny irregularities, possibly inclusions, and the lack of radial fibrous structure surfaces of ancient oolites. Technique for making plastic replicas of the surface is outlined. Twenty-seven elecron micrographs are here reproduced.