Contents

Contents iii
Abstract 1
Introduction 1
Some basic terms and concepts 3
Overview of geologic and tectonic history 6
Principal commodities and deposit types 8
　Metals 10
　　Beryllium 10
　　Cobalt 11
　　Copper 13
　　Gold 17
　　Iron ore 21
　　Lead and zinc 23
　　Molybdenum 26
　　Platinum-group elements and nickel 28
　　Rare-earth elements 31
　　Silver 33
　　Titanium 38
　Industrial materials 40
　　Barite 40
　　Bentonite 42
　　Boron 44
　　Bromine 46
　　Diatomite 47
　　Garnet 48
　　Gypsum 49
　　Kaolin 50
　　Phosphate rock 51
　　Potash 53
　　Salt (halite) 54
　　Soda ash (sodium carbonate) 56
　　Talc 58
Regional exploration history and significant recent discoveries 59
Potential for undiscovered mineral resources 62
References cited 65

Figures 79
Appendix 1. Major mineral deposits in the United States 125
Appendix 2. Selected criteria used to identify major mineral deposits listed in Table 2 of this report 171
Appendix 3. Resource-reserves definitions (USGS, 2004) 172

Tables
Table 1. Value of selected mineral commodities produced in the United States....................2
Table 2. Beryllium - proportion of world mine production for the United States...................10
Table 3. Cobalt - proportion of world mine production, reserves, and reserve base for the United States...11
Table 4. Copper - proportion of world mine production, reserves, reserve base, and resource base for the United States...13
Table 5. Gold - proportion of world mine production, reserves, and reserve base for the United States...17
Table 6. Iron ore - proportion of world mine production, reserves, and reserve base for the United States...21
Table 7. Lead - proportion of world mine production, reserves, and reserve base for the United States...23
Table 8. Zinc - proportion of world mine production, reserves, and reserve base for the United States...23
Table 9. Molybdenum - proportion of world mine production, reserves, and reserve base for the United States...26
Table 10. Platinum-group elements - proportion of world mine production, reserves, and reserve base for the United States...28
Table 11. Rare-earth elements - proportion of world mine production in 2002 and 2003, reserves, and reserve base for the United States...31
Table 12. Silver - proportion of world mine production, reserves, and reserve base for the United States...33
Table 13. Titanium concentrate (ilmenite) - proportion of world mine production, reserves, and reserve base for the United States...38
Table 14. Barite - proportion of world mine production, reserves, and reserve base for the United States...40
Table 15. Bentonite - proportion of world mine production for the United States................42
Table 16. Boron - proportion of world mine production, reserves, and reserve base for the United States...44
Table 17. Bromine - proportion of world mine production for the United States...................46
Table 18. Diatomite - proportion of world mine production and reserves for the United States...47
Table 19. Garnet - proportion of world mine production for the United States......................48
Table 20. Gypsum - proportion of world mine production for the United States...................49
Table 21. Kaolin - proportion of world mine production for the United States.......................50
Table 22. Phosphate rock - proportion of world mine production, reserves, and reserve base for the United States...51
Table 23. Potassium - proportion of world mine production, reserves, and reserve base for the United States...53
Table 24. Salt - proportion of world mine production for the United States...........................54
Table 25. Soda ash - proportion of world mine production, reserves, and reserve base for the United States...56
Table 26. Talc - proportion of world mine production for the United States..........................58

Figures
Figure 1. Map of the World showing the areas covered by this series of regional reports, tectonic plate boundaries, and ocean bathymetry...79
Figure 2. Sketches showing the layered internal structure of the Earth.................................80
Figure 3. Perspective diagram and cross section of the uppermost layers of the Earth illustrating the main types of tectonic plate boundaries...81
Figure 4. A schematic cross-section of the Earth illustrating three types of mantle plumes...82
Figure 5. A map of the globe showing the distribution of the igneous rocks associated with selected large igneous provinces (red regions) that formed in the last 250 million years...83
Figure 6. Map showing the location of the major magmatic and metamorphic mineral deposits of United States...84
Figure 7. Cross section of the uppermost layers of the Earth illustrating the distribution of mineral deposits in relation to the main types of tectonic plate boundaries...85
Figure 8. Map showing the location of the major hydrothermal mineral deposits of United States...86
Figure 9. Map showing the location of the major sedimentary mineral deposits of United States...87
Figure 10. Map showing the location of the major surficial mineral deposits of United States...88
Figure 11. Relative geologic time units used in this report........................................................89
Figure 12. Simplified geologic map of North America................................................................90
Figure 13. Map of North American showing the geology of the North American craton underlying the sedimentary rocks that cover much of the continent..91
Figure 14. Summary of selected geologic events and features for the North American craton in the last 2,000 million years...92
Figure 15. Map showing the location of the major beryllium, copper-cobalt, copper-nickel-PGE, and platinum-palladium mineral deposits of United States...93
Figure 16. Cross section schematically illustrating the characteristic features of an idealized sedimentary-exhalative (sedex) mineral deposit...94
Figure 17. Simplified geologic map showing the distribution of metamorphosed sedimentary rocks (Belt-Purcell Supergroup) deposited in the Middle Proterozoic Belt basin and Cretaceous igneous rocks related to the Cordilleran orogen...95
Figure 18. Map showing the location of the major copper mineral deposits of United States...96
Figure 19. Cross section through an idealized stratovolcano, showing various styles of related mineralization...97
Figure 20. Map illustrating changes in metal content of mineralized rock and ore deposits in the Bingham district, Utah...98
Figure 21. Map showing the distribution of the Middle Proterozoic Revett Formation and associated hydrothermal copper-silver mineralization in northwestern Montana and northern Idaho...99
Figure 22. Map showing selected geologic features and the location of major sedimentary iron deposits (banded iron formation), magmatic copper-nickel-PGE deposits, and hydrothermal copper deposits in basalt...100
Figure 23. Map showing the location of the major gold mineral deposits of United States...101
Figure 24. Map showing the distribution of sedimentary rock-hosted gold deposits and mineralization of the Blue-Star area of the Carlin Trend, Nevada...102
Figure 25. Schematic east-west cross section of northern Nevada and northwest Utah showing the location of Carlin-type gold deposits in relation to large tectonic features...103
Figure 26. Schematic cross section that illustrates generalized patterns of alteration and mineralization of epithermal gold deposits...104
Figure 27. Map showing the location of the major iron, niobium, rare-earth metals, and titanium mineral deposits of United States...105
Figure 28. Map showing the location of the major lead and zinc mineral deposits of United States listed...106
Figure 29. Cross section illustrating the essential features of an idealized volcanogenic massive sulfide deposit...107
Figure 30. Map showing the location of MVT lead-zinc districts in the Ozark region of the United States...108
Figure 31. Map of southeast Missouri showing location of major Mississippi Valley ore districts surrounding outcrops of Precambrian igneous rocks in the St. Francois Mountains...109
Figure 32. Map showing the location of the major molybdenum mineral deposits of United States...110
Figure 33. Idealized section through an ultramafic-to-mafic layered igneous intrusion showing the distribution of magmatic ore deposits...111
Figure 34. Map showing the location of the major silver mineral deposits of United States...112
Figure 35. Map showing heavy mineral deposits in northeastern Florida and southeastern Georgia...113
Figure 36. Map showing the location of the major barite, garnet, and talc mineral deposits of United States...114
Figure 37. Map showing the location of the major sodium bentonite, phosphate rock, diatomite, kaolin, and limestone mineral deposits of United States...115
Figure 38. Map showing the location of the major gypsum, boron, bromine, salt, potash, and sodium carbonate mineral deposits of United States...116
Figure 39. Map showing the location of the major phosphorite deposits relative to the Miocene geologic framework of the southeast Atlantic Coastal Plain-continental shelf system...117
Figure 40. Map showing the distribution the location of major salt and potash deposits in evaporite basins in North America showing. Modified from Kesler (1994)...118
Figure 41. Map showing the distribution of the Green River Formation and the location of sodium carbonate deposits in Utah, Colorado, and Wyoming...119
Figure 42. Map showing the thickness of trona bed 17 and Wyoming state mine permit areas...120
Figure 43. Charts showing the density of exploration sites for selected regions of the United States...121
Figure 44. Graph showing the number of active mining claims held on public lands in the United States from 1976 to 2003...122
Figure 45. Graph showing the number of active mining operations in the United States from 1979 to 2002...123

Abstract

This report, which is one of a series of reports summarizing the World’s endowment of nonfuel mineral resources, describes the location and general geologic setting of deposits of major mineral commodities in the United States. The discussion in this report focuses on those commodities produced in the United States that constituted at least 5 percent of global production or global reserve base in 2003 or had at least $100 million production value in 2001. The discussion for each commodity begins with a brief description of the chemical and physical properties of the material and how it is used. The importance of the commodity in the United States relative to the world is also presented. However, most of the discussion emphasizes the geology of mineral commodities . the important mineral deposit types, their geologic setting, and the processes that led to their formation. A compilation of almost 400 major mineral deposits in the United States is included as an appendix.

Figure 6. Map showing the location of the major magmatic and metamorphic mineral deposits of United States listed in appendix 1. Geologic base is derived from Geological Survey of Canada (1995). Figure 7. Cross section of the uppermost layers of the Earth illustrating the distribution of mineral deposits in relation to the main types of tectonic plate boundaries. Figure 8. Map showing the location of the major hydrothermal mineral deposits of United States listed in appendix 1. Geologic base is derived from Geological Survey of Canada (1995). Figure 9. Map showing the location of the major sedimentary mineral deposits of United States listed in appendix 1. The map also shows the extent of sedimentary basins mentioned in the report. Geologic base is derived from Geological Survey of Canada (1995) and sedimentary basins are from St. John (2000). Figure 12. Simplified geologic map of North America. Modified from Bally and others (1989) and Hoffman (1989). White labels are: CRB . Columbia River flood basalt province; K . Keweenawan flood basalt province; and W, Wrangellia flood basalts. Figure 13. Map of North American showing the geology of the North American craton underlying the sedimentary rocks that cover much of the continent. Modified from Hoffman (1989). Figure 19. Cross section through an idealized stratovolcano, showing various styles of related mineralization. USGSによる『Geology and Nonfuel Mineral Deposits of the United States』から