Critical Metals have come to the forefront of global discussion in the past ten years. Most recently, the US DOI USGS has published a comprehensive study of Minerals currently deemed Critical to the Unites States (1). This book presents resource and geologic information on the following 23 mineral commodities currently among those viewed as important to the national economy and national security of the United States: antimony (Sb), barite (barium, Ba), beryllium (Be), cobalt (Co), fluorite or fluorspar (fl uorine, F), gallium (Ga), germanium (Ge), graphite (carbon, C), hafnium (Hf), indium (In), lithium (Li), manganese (Mn), niobium (Nb), platinum-group elements (PGE), rare-earth elements (REE), rhenium (Re), selenium (Se), tantalum (Ta), tellurium (Te), tin (Sn), titanium (Ti), vanadium (V), and zirconium (Zr). For a number of these commodities-for example, graphite, manganese, niobium, and tantalum-the United States is currently wholly dependent on imports to meet its needs. Of these the Rare Earths have globally received the vast amount of attention. Unfortunately, Criticality is considered both a subjective and localized phenomenon. The US DOE CMI program has further delineated those Critical Materials as a subset that are specifically crucial for Energy and that are largely produced as by products (2,3). Hence, different jurisdictions and countries have varying needs for and applications of various metals. That said, the defining aspect of Criticality is a demand situation coupled with limited availability of supply. Limited availability may be due to many factors and most often is based upon either resource scarcity or control of supply by a singular entity. More importantly, a critical lack of skilled talent or technology is clearly the current and long-term root of this issue (4,5). 2 THE KROLL INSTITUTE FOR EXTRACTIVE METALLURGY The Kroll Institute for Extractive Metallurgy, KIEM, was established in 1974 at the Colorado School of Mines in accordance with a bequest from William J. Kroll, world renowned extractive metallurgist best known for his inventions of processes for the production of titanium and zirconium. The fi nancial resources of Dr. Kroll ' s bequest were intended to provide for the establishment of a Center for Excellence in Extractive Metallurgy at the Colorado School of Mines. Since its inception, the Kroll Institute has provided financial support to both undergraduate and graduate students at CSM, many of whom, subsequently, have made important contributions, nationally and internationally, to the fi elds of mining, minerals, metals and advanced materials. Today, the mission of the Kroll Institute is to support the minerals, metals and materials industries through the following activities: Maintain expertise and research capabilities important to the minerals, metals and materials industries Perform cutting edge research Train process engineers for industry Develop short courses Develop specialty conferences The academic environment creates a unique opportunity to