UNITED STATES MINERAL RESOURCES 



NUCLEAR FUELS 



By Warren I. Finch, Arthur P. Butler, Jr., Frank C. Armstrong, 

 Albert E. Weissenborn, Mortimer H. Staatz, and Jerry C. Olson 



CONTENTS 



Introduction 



Uranium 



Abstract of conclusions 



Introduction 



Exploitation 



Geologic environment 



Geochemical cycle 



Mineralogy 



Types of deposits 



Peneconcordant deposits 



Deposits in quartz-pebble conglomerates 



Vein deposits 



Other epigenetic deposits 



Uraniferous igneous rocks 



Uraniferous phosphatic rocks 



Uraniferous marine black shales 



Resources 



Identified and hypothetical resources 



Recoverable resources 



Conditional resources 



Speculative resources 



Prospecting techniques 



Problems for research 



References cited 



Thorium 



Abstract of conclusions 



Introduction 



Exploitation 



Geologic environment 



Geochemistry 



Ore minerals and associated minerals 



Types of deposits 



Veins 



Placers 



Deposits in sedimentary rocks 



Concentrations in metamorphic and 



igneous rocks 



Resources 



Identified resources 



Hypothetical and speculative resources 



Prospecting techniques 



Research needed on domestic thorium resources- 

 References cited 



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FIGURES 



54. 



Graph shovnng projected domestic uranium re- 

 quirements, 1972-2010 



Graph showing uranium production, 1948-71, 

 from United States and other countries 



Graph showing production of monazite, 1887- 

 1970 



458 



TABLES 



93. Identified uranium resources 



94. Identified thorium resources 



Page 



463 



474 



INTRODUCTION 



By Warren I. Finch 



The increasing demand for energy throughout the 

 world and the decreasing resources of organic fuels 

 place the nuclear fuels, uranium and thorium, in the 

 spotlight of future energy sources. Technologically, 

 uranium's role is well established, but thorium's 

 future use as a fuel is less certain. 



Thorium is about three times more abundant in 

 the earth's crust than uranium. In igneous rocks the 

 two elements are closely associated with each other; 

 in the sedimentary cycle, however, they mostly part 

 ways. The primary thorium minerals are resistant 

 to oxidation, and weather out to form economically 

 important placers. Thorium does not tend to enter 

 the regimen of ground and meteoric water, rarely 

 forms secondary minerals, and thus occurs in far 

 fewer geologic environments than uranium. The 

 primary uranium minerals, except those in which 

 uranium substitutes for thorium, are easily oxidized. 

 The most important placer concentrations of primary 

 uranium minerals are those that are believed to have 

 formed under nearly oxygen-free reducing atmos- 



U.S. GEOL. SURVEY PROF. PAPER 820 



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