As the importance and dependence of specific mineral commodities increase, so does concern about their supply. The United States is currently 100 percent reliant on foreign sources for 20 mineral commodities and imports the majority of its supply of more than 50 mineral commodities. Mineral commodities that have important uses and face potential supply disruption are critical to American economic and national security. However, a mineral commodity's importance and the nature of its supply chain can change with time; a mineral commodity that may not have been considered critical 25 years ago may be critical today, and one considered critical today may not be so in the future. The U.S. Geological Survey has produced this volume to describe a select group of mineral commodities currently critical to our economy and security. For each mineral commodity covered, the authors provide a comprehensive look at (1) the commodity's use; (2) the geology and global distribution of the mineral deposit types that account for the present and possible future supply of the commodity; (3) the current status of production, reserves, and resources in the United States and globally; and (4) environmental considerations related to the commodity's production from different types of mineral deposits. The volume describes U.S. critical mineral resources in a global context, for no country can be self-sufficient for all its mineral commodity needs, and the United States will always rely on global mineral commodity supply chains. This volume provides the scientific understanding of critical mineral resources required for informed decisionmaking by those responsible for ensuring that the United States has a secure and sustainable supply of mineral commodities.

This volume represents an edited selection of papers presented at the International symposium on the geology of tin deposits held in Nanning City in October 1984. It documents a great advance in our knowledge of tin deposits, particularly of the People's Republic of China. Details are presented in English for the first time on the major tin-polymetallic sulphide deposits of Dachang and Gejiu, which bear similarities to the deposits of Tasmania, but are little known to the geological community outside of China. The publication of this volume was sponsored by the United Nations ESCAP Regional Mineral Resources Development Centre (RMRDC), now a Regional Mineral Resources Development Project (RMRDP) within ESCAP. The Centre had previously published a report on the Symposium in Nanning City and the following field trip to the Dachang tin-polymetallic sulphide deposit of Guangxi, entitled "Report on the International Symposium on the Geology of Tin Deposits: Nanning and Dachang, China, 27 October - 8 November 1984". It is my privilege to acknowledge the help provided by Dr. J. F. McDivitt and Dr. H. W. Gebert, co-ordinator of ESCAP-RMRDC.

Mineral Commodity Summaries 2019