179

Guiana, bauxite, 242-243

Gulf Coast region, lignite, 118
petroleum, 132, 135, 137
salt, 298
sulphur, 110
_See also_ Louisiana, Texas, etc.

Gypsum, 100, 283-285, 397

Haas, Frank, 367, 369

"Head" of underground water, 71-73

Heikes, V. C., Butler, B. S., and Loughlin, G. F., 44, 55, 230

Highway building, application of geology to, 90-91

Holland, cement, 87
commercial and political control of various minerals, 64
_See also_ Dutch East Indies, etc.

Homestake Mine, South Dakota, gold ores, 229

Hones, 269

Hoover, Herbert C., 322

Hot springs, relation to ore-deposits, 40, 258-259

Hot waters, evidence of formation of ores by, 37-41

Huancavelica district, Peru, mercury ores, 258

Hudson River, physiographic problems in tunneling under, 415

Hudson's Bay, possible diamond field, 317

Humus, 94

Hunan Province, China, antimony ores, 249

Hungary, antimony, 247
natural gas, 151
_See also_ Austria-Hungary.

Hydrosphere, 18

Hypogene ores, use of term, 32-33

Idaho, coal, 117
lead, 39, 45, 209, 211, 212-213
monazite, 289
phosphates, 105
silver, 234
zinc, 214, 216

Idria, Austria-Hungary, mercury ores, 257

Igneous after-effects, ore-deposits formed as, 19-20, 36-46

Igneous rocks, formation of, 19
mineral deposits associated with, 19-20, 34-46
principal minerals of, 14-16
proportions of principal types, 17
relative abundance of, 17
weathering of, 20

Illinois, clay, 85
coal, 115, 117, 126
fluorspar, 194
limestone, 83
petroleum, 132, 133, 135
pyrite, 109
sand and gravel, 85
tripoli and rottenstone, 269
zinc, 216

Illinois Geological Survey, cooperative exploration for oil, 147, 306

Income tax, application to mineral properties, 336-339

India, bauxite, 242

India, bromine, 277
chromite, 178-179
coal, 115, 116
corundum, 268
diamond dust, 268
gypsum, 283
iron, 154, 164, 165
manganese, 174-176
mica, 286
monazite, 288, 289
petroleum, 128, 129
platinum, 238
salt, 294
zirconium, 189

Indiana, coal, 117, 126
hones, oilstones and whetstones, 269
limestones, 83
petroleum, 133, 135

Interest rate, as a guide in conservation, 364
choice of for valuation purposes, 233
limiting effect on acquirement of reserves, 334