This monograph represents a tribute to the late Prof. Karl Gschneidner, well known as "Mr. Rare Earth", distinguished Professor of Materials Science and Engineering at the Iowa State University, a Senior Metallurgist at the Ames Laboratory, and the Chief Scientist of the Critical Materials Institute. Topics covered include Rare Earth Glass Spectroscopy, Treating Skin Diseases, Prospective Rare Earth Applications, Optical Information Storage, Diagnostic Imaging, Nanoparticles in Glasses, and ZnO Nanomaterials.