Economic geology of the United States

Preface

The following work on the Economic Geology of the United States covers essentially the ground which is gone over in the elementary course in this subject in Cornell University, but it is hoped that -it will prove useful as a text-book in other colleges.

The mode of arrangement is markedly different from that found in other books on the same subject, in that the non-metallic minerals are discussed first and the metallic minerals last. This, to the author, seems the most desirable method of treatment, for the reason that the non-metallics are not only the most important, the value of their production having exceeded the metallics by over one hundred and fifty million dollars in 1903, but also because it leads from a discussion of the simpler to the more complex forms of mineral deposits.

It has not been thought desirable to include a chapter on geologic and physiographic principles, since the space which could be allotted to it is altogether too small, and, moreover, the study of economic geology presupposes a knowledge of geology and mineralogy on the. part of the student. While the references given at the end of each chapter do not include every paper that has been written on the subject to which they refer, still it is believed that they are sufficiently numerous to permit one to follow out the subject in considerable detail if he so desire.

In the preparation of the manuscript all available sources of information have been freely drawn upon, and the numbers in parentheses in the text refer to the numbered references at the end of each chapter.

v

VI PREFACE

All statistical figures, unless otherwise stated, are taken from the reports of the United States Geological Survey.

Descriptions of mineral occurrences in foreign countries are not included, except in a few cases where the deposits serve as an important if not the only source of supply for the United States.

The writer wishes to express his thanks to Professor R. S. Tarr for examination and criticism of much of the manuscript, and to W. E. McCourt, Instructor in Geology, and H. Leighton, Assistant in Geology, for aid in the preparation of drawings and statistical tables. For the loan of photographs or cuts acknowledgments are due to Messrs. H. F. Bain, J. E. Spurr, J. M. Boutwell, G. H. Eldridge, W. Lindgren, F. H. Oliphant, and J. H. Pratt of the United States Geological Survey ; Professor A. C. Lane, Michigan Geological Survey ; Dr. D. H. Newland, New York State Museum ; Professor C. C. O'Harra, South Dakota School of Mines; Professor E. A. Smith, Alabama Geological Survey; Professor G. H. Perkins, Vermont Geological Survey ; Dr. H. B. Kummel, New Jersey Geological Survey ; Dr. W. B. Phillips, Texas Geological Survey; Dr. G. P. Merrill, United States National Museum; also to Messrs. H. W. Turner, F. S. Witherbee, A. W. Sheafer, L. Martin, Wiley & Sons, Vermont Marble Co., and Bedford Quarries Co.

Cornell University, Ithaca, N.Y., June, 1905.

Contents

PAGE

Preface ..... v

Contents vii

List of Illustrations . . . . . xv

List of Abbreviations xxi

CHAPTER I Coal 3-38

Kinds of coal, 3 ; Peat, 3 ; Lignite, 4 ; Bituminous coal, 4 ; Cannel coal, 5 ; Semi-bituminous coal, 5 ; Anthracite coal, 5 ; Proximate analysis of coal, C ; Origin of coal, 9 ; Conditions of vegetable accumulation, 10 ; Chemical changes occurring during coal formation, 12 ; Effect of heat and pressure, 14 ; Structural features of coal beds, 15 ; Outcrops, 15 ; Associated rocks, 16 ; Variations in thickness, 16 ; Other irregularities, 17 ; Coal fields of the United States, 18; Geologic distribution of coals in the United States, 10 ; Appalachian field, 20 ; Bituminous area, 21 ; Character of Appalachian bituminous coals, 22 ; Pennsylvania anthracite field, 22 ; Rhode Island field, 25 ; The Triassic field, 25 ; Eastern Interior field, 26 ; Northern Interior field, 27 ; Western Interior field and southwestern fields, 28 ; Western Interior field, 29 ; Southwestern field, 20 ; Gulf states lignite area, 30 ; Rocky Mountain fields, 30 ; The Pacific Coast fields, 31 ; Alaska, 32 ; Production of coal, 33 ; Production of coke, 35 ; References on coal, 35 ; References on peat, 38.

CHAPTER II Petroleum, Natural Gas, and Other Hydrocarbons . . 39-68

History of petroleum development, 39 ; History of natural gas

development, 40 ; Properties of petroleum, 40; Properties of natural

gas, 42 ; Mode of occurrence, 43 ; Pressure of oil and gas wells, 44 ;

Origin, 46 ; Inorganic theory, 46 ; Organic theory, 47 ; Geological

Vlll CONTENTS

PAGE

distribution of petroleum and natural gas, 48 ; Distribution of petroleum in the United States, 48 ; Appalachian field, 48 ; Ohio- Indiana field, 50 ; Texas-Louisiana oil fields, 51 ; Kansas, 52 ; California, 52 ; Wyoming, 53 ; Colorado, 53 ; Alaska, 54 ; Distribution of natural gas in the United States, 54 ; New York, 54 ; Pennsylvania, 54 ; West Virginia, 55 ; Ohio, 55 ; Indiana, 55 ; Kansas, 55 ; Uses of petroleum, 56 ; Uses of natural gas, 56 ; Oil shales, 56 ; Solid bitumens, 57 ; Occurrence, 57 ; Asphaltites, 58 ; Albertite, 59 ; Anthraxolite, 59 ; Ozokerite, 59 ; Grahamite, 59 ; Lake asphalt, 59 ; Uintaite or gilsonite, 59 ; Manjak, 59 ; Bituminous rocks, 60 ; Analyses, 60 ; Uses, 61 ; Production of petroleum, natural gas, and asphaltum, 61 ; Eeferences on petroleum, 66 ; References on natural gas, 67 ; References on oil shale, 67 ; References on asphaltum, 67.

Chapter III

Properties of building stones, 69 ; Color, 70 ; Texture, 70 ; Density, 70 ; Hardness, 71 ; Strength, 71 ; Crushing strength, 72 ; Transverse strength, 72 ; Porosity and ratio of absorption, 73 ; Resistance to frost, 73 ; Resistance to heat, 73 ; Structural features affecting quarrying, 74 ; Bedding planes, 74 ; Granites, 75 ; Characteristics of granites, 75 ; Distribution of granites in the United States, 76 ; Eastern crystalline belt, 77 ; Central states, 77 ; Western states, 77 ; Uses of granite, 77 ; Miscellaneous igneous rocks, 78 ; Limestones and marbles, 78 ; General characteristics, 78 ; Varieties of limestones, 79 ; Distribution of limestones in the United States, 80 ; Distribution of marbles in the United States, 81 ; Onyx marbles, 83 ; Serpentine, 83 ; Sandstones, 84 ; General properties, 84 ; Varieties of sandstone, 85 ; Distribution of sandstones in the United States, 86 ; Uses of sandstones, 87 ; Slates, 87 ; General characteristics, 87 ; Distribution of slates in the United States, 88 ; Uses of slate, 89 ; Production of building stones, 89 ; References on building stones, 90 ; References on onyx marble, 91.

Chapter IV

Definition, 92 ; Residual clays, 92 ; Sedimentary clays, 93 ; Marine clays, 94 ; Elood-plain clays, 94 ; Lake clays, 94 ; Glacial clays, 94 ; iEolian clays, 94 ; Properties of clay, 95 ; Chemical properties, 95 ; Physical properties, 96 ; Plasticity, 96 ; Tensile strength, 96 ; Shrinkage, 96 ; Fusibility, 97 ; Specific gravity, 97 ;

CONTEXTS IX

Chemical composition, 97 ; Classification of clay, 98 ; Kinds of clay, 99 ; Geological distribution, 100 ; Distribution of clays in the United States by kinds, 100 ; Kaolins, 100 ; Fire clays, 102 ; Pottery clays, 103 ; Brick and tile clays, 104 ; Miscellaneous clays of importance, 104 ; Uses of clay, 105 ; Production of clay, 105 ; Eeferences on clay, 106.

Chapter V

Composition of limestone, 109 ; Changes in burning, 110 ; Lime, 110; Hydraulic cements, 111; Pozzuolano cements, 111; Hydraulic limes, 112 ; Natural rock cements, 112 ; Portland cement, 113 ; Distribution of lime and cement materials in the United States, 116 ; Limestone for lime. 116 ; Hydraulic limes. 117 ; Natural rock cement, 117 ; Portland cements, 118 ; Uses of lime, 119 ; Uses of cement, 119 ; Production of cement, 120 ; References on lime and cement materials, 121.

Chapter VI

Salt, 124 ; Occurrence of salt in sea and lake waters. 124 ; Rock salt, 125 ; Origin of rock salt, 125 ; Natural brines, 127 ; Salt marshes and soils, 127 ; Distribution of salt in the United States, 127; New York. 127; Michigan. 129; Other eastern states, 129; Louisiana, 129 ; Kansas, 130 ; Other western states, 130 ; Extraction, 131 ; Uses, 132 ; Production of salt. 132 ; References on salt. 134; Borax, 134; Borax minerals, 134; Distribution in United States, 134 ; Uses, 134 ; Production of borax, 136 ; References on borax, 136; Sodium sulphate, 136; References, 137; Sodium carbonate, 137 ; References, 137 ; Soda niter, 137 ; References, 138.

Chapter VII

Gypsum, 139 ; Anhydrite, 139 ; Origin of gypsum, 139 ; Gypsite,

140 ; Distribution in the United States, 140 ; Iowa. 140 ; Kansas,

141 ; Michigan, 142 ; New York, 142 ; Other occurrences, 142 ; Analyses, 143 ; Uses, 143 ; Production of gypsum, 145 ; References on gypsum, 146.

Chapter VIII

Phosphate of lime, 147 ; Apatite, 147 ; Amorphous phosphates. 147 ; Florida phosphates, 148 ; Land pebble or matrix rock, 149 ;

CONTENTS

PAGE

River pebble, 149 ; South Carolina phosphates, 150 ; Tennessee phosphates, 150 ; Other phosphate occurrences, 153; Composition, 153 ; Uses, 154 ; Guano, 155 ; Greensand, 155 ; Production, 156 ; References on fertilizers, 157.

Chapter IX

Introductory, 158 ; Grindstones, 158 ; Whetstones and oilstones, 159 ; Buhrstones and millstones, 161 ; Pumice and volcanic ash, 161 ; Infusorial earth and tripoli, 162 ; Crystalline quartz, 163 ; Garnet, 163 ; Corundum and emery, 163 ; Artificial abrasives, 165 ; Production of abrasives, 165 ; References on abrasives, 166.

Chapter X

Asbestos, 167 ; Asbestos minerals, 167 ; Distribution, 167 ; Uses, 169 ; Production of asbestos, 169 ; References on asbestos, 169 ; Barite, 170 ; Uses, 170 ; Production, 170 ; References on barite, 171 ; Fluorspar, 171 ; Distribution in United States, 172 ; Uses, 173 ; References on fluorspar, 174; Fuller's earth, 174; Production of fuller's earth, 176 ; References on fuller's earth, 176 ; Glass sand, 176 ; References on glass sand, 178 ; Graphite, 178 ; Distribution of graphite in the United States, 178 ; Uses, 179 ; Production of graphite, 180 ; References on graphite, 181 ; Lithographic stone, 181; References on lithographic stone, 183; Lithium, 183; Magnesite, 183 ; References on magnesite, 184 ; Mica, 184 ; References on mica, 186 ; Mineral pigments, 186 ; Hematite, 186 ; Ochers, 186 ; Slate, 187 ; Gypsum, 187 ; Barite, 187 ; Asbestos, 188 ; Graphite, 188 ; Calcium carbonate, 188 ; Other paints, 188 ; Production of mineral pigments, 189 ; References on mineral paints, 189 ; Molding sand, 189 ; References on molding sand, 190 ; Monazite, 190 ; Uses, 191 ; Production of monazite, 191 ; References on monazite, 191 ; Precious stones, 192 ; Diamond, 192 ; Ruby, 193 ; Sapphire, 193; Emerald, 193; Topaz, 194; Turquoise, 194; Garnet, 194; Opal, 195 ; Other precious stones, 195 ; Production of precious stones, 195 ; References on precious stones, 196 ; Sulphur and pyrite, 196 ; Sulphur, 196 ; Solfataric type, 196 ; Gypsum type, 197 ; Uses, 198 ; Production of sulphur, 198 ; References on sulphur, 199; Pyrite, 199; Distribution, 199; Uses, 200; References on pyrite, 200 ; Strontium, 200 ; Uses, 201 ; References on strontium, 201 ; Talc and soapstone, 201 ; Uses, 202 ; Pyrophyllite, 203 ; Production, 203 ; References on talc and soapstone, 203.

CONTENTS XI

Chapter XI Page

Mineral waters, 204 ; Distribution of mineral waters in the United States, 205 ; Production of mineral waters, 206 ; References on mineral waters, 207 ; Underground waters, 207 ; Ground water, 207 ; Artesian waters, 209 ; References on underground water, 211.

CHAPTER XII Soils and Road Materials 213-219

Soils, 213 ; Origin, 213 ; Residual soils, 213 ; Transported soils, 213 ; Properties of soils, 213 ; Chemical properties, 214 ; Physical properties, 215 ; Distribution of soils in the United States, 216 ; References on soils, 216 ; Road materials, 217 ; References on road materials, 219.

Chapter XIII

Definition, 223 ; Gangue minerals, 223 ; Origin of ore bodies, 224 ; Ores of contemporaneous origin, 224 ; Concentration of ores in rocks, 225 ; Formation of cavities, 231 ; Precipitation of metals from solution, 232 ; Replacement or metasomatism, 233 ; Concentration by eruptive after-action or pneumatolysis, 234 ; Other causes of precipitation, 235 ; Forms of ore bodies, 236 ; Fissure veins, 236 ; Other forms of ore deposits, 241 ; Secondary changes in ore deposits, 242 ; Weathering or superficial alteration, 242 ; Secondary deposition below water level, 244 ; Value of ores, 245 ; Classification of ore deposits, 246 ; References on ore deposits, 249.

Chapter XIV

Ores of iron, 251 ; Magnetite, 254 ; Distribution of magnetites in the United States, 254 ; Non-titaniferous magnetites, 254 ; Other occurrences, 254 ; Titaniferous magnetites, 257 ; Magnetite sands, 258 ; Hematite, 259 ; Distribution of hematite ores in the United States, 259 ; Lake Superior region, 259 ; Clinton ore, 266 ; Other

Xll CONTENTS

PAGE

hematite occurrences, 268 ; Limonite, 269 ; Bog ores, 269 ; Residual limonites, 270 ; Other occurrences, 271 ; Siderite, 272 ; Production of iron ores, 273 ; References on iron ores, 276.

Chapter XV

Ores, 278 ; Impurities in copper ores, 280 ; Superficial alteration of copper ores, 280 ; Distribution of copper ores in the United States, 281 ; Montana, 282 ; Michigan, 287 ; Arizona, 290 ; Bisbee or Warren district, 290 • Jerome district, 292 : Clifton district, 293 ; Globe district, 294 ; Appalachian region, 294 ; Utah, 296 ; California, 297 ; Other occurrences, 298 ; Uses of copper, 298 ; Production of copper, 299 ; References on copper, 301.

Chapter XVI

Ores of lead, 303 ; Ores of zinc, 303 ; Superficial alteration of lead and zinc ores, 305 ; Distribution of lead and zinc ores in the United States, 305 ; Lead alone, 306 ; Appalachian belt, 306 ; Southeastern Missouri, 306 ; Desilverized lead, 307 ; Zinc ores alone, 307 ; Eastern and southern states, 308 ; Sussex County, N.J., 308 ; Virginia and Tennessee, 310 ; Pennsylvania, 311 ; Lead and zinc ores of the Mississippi Valley region, 311 ; Upper Mississippi Valley area, 311 ; Ozark region, 314 ; Origin of the ores, 316 ; Rocky Mountain states, 318 ; Uses of lead and zinc, 319 ; Uses of lead, 319 ; Uses of zinc, 320 ; Production of lead and zinc, 321 ; References on lead and zinc, 323.

Chapter XVII

Ores of gold, 325 ; Ores of silver, 325 ; Mode of occurrence, 326 ; Weathering and secondary enrichment, 327 ; Classification, 327 ; Geological distribution, 329 ; Extraction, 329; Distribution of gold and silver ores, 331 ; Cordilleran region, 332 ; Pacific coast Cretaceous gold-quartz ores, 332 ; Mother Lode belt, 333 ; Nevada County, 334 ; Central belt of gold-silver ores, 335 ; Mercur, Utah, 336 ; Other occurrences, 337 ; Eastern belt of Tertiary gold-silver veins, 337 ; Cripple Creek, 338 ; San Juan region, 341 ; Tonopah, Nev. , 343 ; Comstock Lode, Nev. , 344 ; Other occurrences, 345 ; Auriferous gravels, 346 ; Black Hills region, 350 ; Homestake belt,

CONTENTS Xlll

PAGE

351 ; Siliceous Cambrian ores, 852 ; Michigan region, 352 ; Eastern crystalline belt, 352 ; Alaska, 353; Uses of gold, 357 ; Uses of silver, 358 ; Production of gold and silver, 358 ; References on gold and silver, 360.

CHAPTER XVIII Silver-Lead 364-374

Silver-lead ores, 364 ; Lead ville District, Colo., 364 ; Aspen, Colo., 367 ; Other occurrences, 369 ; Park City, Utah. 370 ; Tintic District, Utah, 372 ; Cceur d'Alene, Ido., 372 ; Montana, Nevada, etc., 373 ; References on silver-lead ores, 374.

CHAPTER XIX Aluminum, Manganese, and Mercury 375-395

Ores of aluminum, 375 ; Distribution of bauxite in the United States, 376 ; Georgia-Alabama, 877 ; Arkansas, 378 ; New Mexico, 379 ; Uses of aluminum, 379 ; Uses of bauxite, 380 ; Production of bauxite and aluminum, 380 ; References on bauxite and aluminum, 383 ; Manganese, 383 ; Manganese ores, 383 ; Origin, 384 ; Distribution of manganese ores in the United States, 384 ; Eastern area, 885 ; Arkansas, 387 ; Other United States occurrences, 387 ; Uses of manganese, 388 ; Production of manganese, 388 ; References on manganese, 390 ; Ores of mercury, 390 ; Mode of occurrence, 390 ; Distribution in the United States, 390 ; California, 391 ; Texas, 392 ; Origin, 393 ; Uses of mercury, 393 ; Production of mercury, 394 ; References on mercury, 395.

CHAPTER XX Minor Metals 396-417

Ores of antimony, 396 ; Distribution of antimony in the United States, 396 ; Uses, 397 ; Production of antimony, 397 ; References on antimony, 397 ; Arsenic, 398 ; References on arsenic, 398 ; Bismuth, 399 ; Ores, 399 ; Distribution, 399 ; Uses and production,

399 ; Ores of chromic iron, 399 ; Origin of chromite, 400 ; Analyses,

400 ; Distribution of chromic iron in United States, 400 ; Uses, 401 ; Production of chromite, 402 ; References on chromic iron ore, 402 ; Molybdenum, ores and occurrences, 403 ; Uses of molybdenum, 403 ; Production of molybdenum, 403 ; References on molybdenum, 403 ; Nickel and cobalt, 403 ; Ores, 403 ; Distribution, 404; Eastern occurrences of nickel, 404 ; Other occurrences, 405 ; Uses of nickel, 405 ; Uses of cobalt, 406 ; Production, 406 ; References on nickel

XIV CONTENTS

and cobalt, 407; Platinum group of metals, 407; Platinum, 407; Distribution in the United States, 407 ; Uses of platinum, 408 ; Production of platinum, 408 ; References on platinum, 409 ; Palladium, 409 ; Osmium, 409 ; Iridium, 410 ; Tin, 410 ; Ores, 410 ; Mode of occurrence, 410 ; Distribution in the United States, 411 ; Uses of tin, 412 ; Production of tin, 412 ; References on tin, 413 ; Titanium, 413 ; Ores, 413 ; Occurrence, 413 ; Uses, 414 ; References on titanium, 414 ; Tungsten, 414 ; Ores, 414; Occurrence, 415 ; Uses, 415 ; Production, 415 ; References on tungsten, 416 ; Uranium and vanadium, 416 ; Ores, 416 ; Uses, 416 ; Production, 416 ; References on uranium and vanadium, 417.

LIST OF ILLUSTRATIONS

FIG. PAGE

1. Diagram showing changes occurring in passage of vegetable tissue

to graphite 13

2. Section in coal measures of western Pennsylvania, showing fire

clay under coal beds 16

3. Section showing irregularities in coal seam, a, split ; b, parting of

shale ; c, pinch ; d, swell ; e, cut out 17

4. Section of faulted coal seam 17

5. Section across Coosa, Ala. , coal field, showing folding and faulting

characteristic of southern end of Appalachian coal field . . 20

6. Map of Pennsylvania anthracite field 23

7. Sections in Pennsylvania anthracite field 24

8. Coal breaker in Pennsylvania anthracite region .... 25

9. Section across Eastern Interior coal field 26

10. Shaft house and tipple, bituminous coal mine, Spring Valley, 111. . 27

11. Generalized section of Northern Interior coal field .... 28

12. Composite section showing structure of lower coal measures in Iowa 29

13. Section of anticlinal fold showing accumulation of gas, oil, and

water 43

14. Map showing oil and gas fields of United States .... 49

15. Geological section in Ohio-Indiana oil and gas field ... 50

16. Section of Spindle Top oil field near Beaumont, Tex. ... 51

17. Section in Los Angeles oil field 53

18. Map of asphalt and bituminous rock deposits of United States . 58

19. Section of Gilsonite vein, Utah 59

20. Map showing distribution of crystalline rocks (mainly granite) in

21. Map showing marble areas of eastern United States ... 81

22. Section showing cleavage and bedding in slate .... 87

23. Section in slate quarry with cleavage parallel to bedding, a, purple

slate ; 6, unworked ; c and d, variegated ; e and /, green ;

g and h, gray green ; j, quartzite ; j, gray with black patches . 88

24. Section showing formation of residual clay 93

25. Section of a sedimentary clay deposit 93

26. Map showing distribution of salt-producing areas in United States,

compiled from various geological survey reports . . . 128

27. Map showing gypsum-producing localities of United States . . 141

28. Map of Florida phosphate deposits 148

29. Map of Tennessee phosphate areas 151

xv

XVI LIST OF ILLUSTRATIONS

FIG

PAGE

30. Vertical section showing geologic position of Tennessee phosphates 152

31. Map showing distribution of abrasives in United States . . . 159

32. Section showing occurrence of corundum around border of dunite

mass . 164

33. Asbestos vein in serpentine . . 168

34. Ideal section across a river valley, showing the position of ground

water and the undulations of the water table with reference to

the surface of the ground and bed rock 208

35. Geologic section of Atlantic Coastal Plain, showing water-bearing

horizons 210

36. Section from Black Hills across South Dakota, showing artesian

well conditions 211

37. Replacement vein in syenite rock, War Eagle mine, Rossland, B.C.

a, granular orthoclase with a little sericite ; b, secondary biotite ;

q, secondary quartz ; c, chlorite ; black, secondary pyrrhotite 234

38. Section of vein in Enterprise mine, Rico, Colo. The right side

shows later banding due to reopening of the fissure . . . 237

39. Section showing change in character of vein passing from gneiss (g)

to soft shale (jp) 238

40. Tabulation of strikes of principal veins in Monte Cristo, Wash.,

district 239

41. Linked veins 240

42. Gash vein with associated "flats" and "pitches" — Wisconsin

zinc region 240

43. Section at Bonne Terre, Mo., showing ore disseminated through

44. Section through Copper Queen mine, Bisbee, Ariz., showing varia-

ble depth of weathering 243

45. Map showing distribution of iron ores in United States . . . 253

46. Map of Lake Superior iron regions, shipping ports, and transporta-

tion lines 259

47. Sections of iron ore deposits in Marquette range .... 260

48. Generalized vertical section through Penokee-Gogebic ore deposit

and adjacent rocks, Colby mine, Bessemer, Mich. . . . 261

49. Generalized vertical section through Mesabi ore deposit and adja-

cent rocks 262

50. Section of Clinton ore beds, Oxmoor, Ala. a, red sandstone, 5' ;

6, yellow sandstone, 6' ; c, red sandstone, 15' ; d, ore, 22', upper 2' soft ; e, shale, 6' ; /, rich ore, 2' 6" . . . . 266

51. Section illustrating formation of residual limonite in limestone . 270

52. Map showing distribution of copper ores in United States . . 282

53. Map of Butte, Mont., district, showing distribution of veins and

geology 283

54. Section at Butte, Mont., showing mode of occurrence of the ore . 284

LIST OF ILLUSTRATIONS XV11

FIG. PAGE

55. Section across Keweenaw Point . .... 287

56. Section showing occurrence of amygdaloidal copper, Quincy mine,

57. Geological section at Bisbee, Ariz 291

58. Generalized section of ore bodies at Bisbee, Ariz 292

59. Section of Morenci district. P, porphyry ; S, unaltered sediments ;

F, fissure veins ; M, metamorphosed limestone and shale ;

O, contact metamorphic ores ; R, disseminated chalcocite . 293

60. Section of ore body at Bully Hill, Calif 298

61. Map showing distribution of lead and zinc ores in United States . 305

62. Generalized section of southeastern Missouri lead region . . 306

63. Model of Franklin zinc-ore body 309

64. Section of Bertha zinc mines, Wythe County, Va., showing irregu-

lar surface of limestone covered by residual clay bearing ore . 310

65. Section showing occurrence of lead and zinc ores in Wisconsin,

with fissure ore in flats and pitches, and disseminated ore in

oil rock 312

66. Map of Ozark region 314

67. Generalized section showing occurrence of lead and zinc ore in

southwestern Missouri 315

68. A typical hoisting outfit in the southwestern Missouri zinc region . 316

69. Map showing distribution of gold and silver ores in United States . 331

70. Map and section of portion of Mother Lode district, Calif. Pgv,

river gravels, usually auriferous ; Ng, auriferous river gravels. Sedimentary rocks : Jm, inariposa formation (clay, slate, sandstone, and conglomerate) ; Cc, calaveras formation (slaty mica schists). Igneous rocks : Nl, latite ; Nat, andesite tuffs, breccia, and conglomerate ; mdi, meta-diorite; Sp, serpentine ; ma, meta-andesite ; ams, amphibole schist .... 334

71. Section illustrating relations of auriferous quartz veins at Nevada

City, Calif 335

72. Section at Mercur, Utah 336

73. Map of Colorado showing location of mining regions . . . 338

74. Section of vein at Cripple Creek, Colo 339

75. Geologic map of Telluride district, Colorado, showing outcrop of

more important veins 342

76. Ideal cross section of rocks at Tonopah, Nev 343

77. Section of Comstock Lode. D, diorite ; Q, quartz ; V, vein matter

in earlier diabase (Db) ; H, earlier hornblende andesite ;

A, augite andesite * 344

78. Generalized section of old placer, with technical terms, a, volcanic

cap ; b, upper lead ; c, bench gravel ; d, channel gravel . . 347

79. Section of Homestake Belt at Lead, S.D., showing relation of

ancient and modern placers to Homestake Lode . . . 350

XV111 LIST OF ILLUSTRATIONS

FIG. PAGE

80. Typical section of siliceous gold ores, Black Hills, S.D. . . . 351

81. Map showing mineral deposits of Alaska as far as known . . 354

82. Sketch map of Douglas Island, Alaska 355

83. Cross section through Alaska Treadwell mine on nonhern side of

Douglas Island 356

84. Ideal section across Leadville district 366

85. Section of ore body at Aspen, Colo. 368

86. Diagrammatic section across a northeasterly lode at Rico, Colo.,

showing " blanket " of ore 369

87. Vein filling a fault fissure, Enterprise mine, Rico, Colo. . . 370

88. Section of lead-silver vein, Cceur d'Alene, Ido 373

89. Geologic map of Alabama-Georgia bauxite region .... 377

90. Section of bauxite deposit, a, Residual mantle ; 6, Red sandy clay

soil; c, Pisolitic ore; d, Bauxite with clay; e, Clay with

bauxite ; /, Talus ; g, Mottled clay ; h, Drainage ditch . . 378

91. Map showing Georgia manganese areas 385

92. Section in Georgia manganese area showing geologic relations of

manganese, limonite, and ocher 386

93. Section of Batesville, Ark., manganese region, illustrating geological

structure and relation of different formations to marketable

and non-marketable ore 387

94. Map of California mercury localities 391

95. Map showing Texas mercury region 392

96. Section of cinnabar vein in limestone, Terlingua, Tex. . . . 393

97. Sketch map showing location of Carolina tin belt .... 411

PLATES

PLATE PAGE

I. Map showing distribution of coal in United States. Frontispiece II. Fig. 1. Pit working (stripping) near Milnesville, Pa. The

mammoth seam is uncovered in bottom of pit . . . 31 Fig. 2. Lignite seam, Williston, N.D 31

III. Fig. 1. General view of Tuna Valley, in Pennsylvania oil field 48 Fig. 2. View in Los Angeles, Calif., oil field. Such close spacing of oil derricks tends to hasten the exhaustion of the

oil supply 48

IV. General view of Spindle Top oil field, Beaumont, Tex. . . 51 V. Fig. 1. Quarry of bituminous sandstone, Santa Cruz, Calif. . 60

Fig. 2. Granite quarry, Hard wick, Vt 60

VI. Quarry in limestone, Bedford, Ind. 80

VII. Marble quarry, Proctor, Vt 82 -

VIII. View of green slate quarry, Pawlet, Vt 88 /

IX. Bank of sedimentary clay, Woodbridge, N.J. This section

affords at least five kinds of clay 103 '

X. Fig. 1. Quarry of natural cement rock, Cumberland, Md. . 117 Fig. 2. Marl pit at Warners, N.Y. The dark streaks are

peat and the marl is underlain by clay . . . .117

XI. Fig. 1. Interior view of salt mine, Livonia, N.Y. . . . 12!)

Fig. 2. Borax mine near Daggett, Calif. .... 129

XII. Fig. 1. Gypsum quarry, Alabaster, Mich. Shows gypsum overlain by glacial drift, The dump in foreground is overburden removed from gypsum ...... 139

Fig. 2. Rock phosphate mine near Ocala, Fla. . . . 139

XIII. Fig. 1. Grindstone quarry, Tippecanoe, Ohio .... 159 Fig. 2. Corundum vein between peridotite and gneiss, Corundum Hill, Ga 159

XIV. Fig. 1. View of open cut in magnetite deposit, Mineville, N.Y.

The pillars are ore left standing to support the gneiss

Fig. 2. General view of magnetic separating plants and shaft

houses, Mineville, N.Y 254

XV. Fig. 1. Iron mine, Soudan, Minn. Shows old open pit with

jasper horse in middle 261

Fig. 2. Outcrop of Clinton iron ore, Red Mountain, near

Birmingham, Ala 261

XX

PLATES

PLATE

XVI.

XVII.

XVIII.

XIX.

XX.

XXI.

XXII.

XXIII.

XXIV.

XXV.

PAGB

General view of Mountain Iron mine, Mesabi Eange, Minn.

Shows mining of ore with steam shovels and covering

of (a) glacial drift 264

Fig. 1. Pit of residual limonite, Shelby, Ala 270 I

Fig. 2. Old limonite mine, Ivanhoe, Va., showing pinnacled

surface of limestone which underlies the ore-bearing clay.

The level of surface before mining began is seen on either

side of excavation 270

Anaconda group of mines, Butte, Mont 285

Fig. 1. Smelter of Clifton Copper Co., Clifton, Ariz. . . 293 ,

Fig. 2. View of Bingham Canon, Utah 293

Fig. 1. Kennedy mine on the Mother Lode near Jackson,

Calif 333/

Fig. 2. Auriferous quartz veins in Maryland mine, Nevada

City, Calif 333

Fig. 1. View of Independence mine and Battle Mountain,

Cripple Creek, Colo 340

Fig. 2. General view of region around Tonopah, Nev. . . 340 Fig. 1. Hydraulic mining of auriferous gravel. The sluice

box in foreground is for catching the gold .... 348