X rays have been used extensively in the study of hard tissue such as bone. The x rays used are typically of energy 50 keV, which have an absorption depth of approximately 1.5 cm in hard tissue. These x rays are used for creating x-ray shadowgraphs (or radiographs) of bones where the finest details recorded are of the order of a few tenths of a millimeter. However, due to the advent of x-ray sources which are energy tunable, and the availability of high resolution x-ray optics, an entirely new range of contrast is now possible along with resolution down to a few tens of nanometers. These new x-ray sources and optics have been combined to create a variety of x-ray microscopes which are now being used in a range of unique applications.