, 129, 137, 144
silver, 231-232, 233
vanadium, 188
zinc, 214-215

Mexico, commercial and political control of various minerals, 64

Miami, Arizona, copper ores, 33, 47, 48, 198, 203, 208

Mica, 285-288, 398

Michigan,
bromine, 277
copper, 199
grindstones and pulpstones, 269
gypsum, 284
iron. _See_ Lake Superior iron ores, Gogebic district, etc.
limestone, 83
salt, 294, 297

Michigan, taxation of iron ores, 335

Midcontinent field, petroleum, 132, 135, 137, 141, 146

Military geology, preparation of textbook, 407

Military operations, relation of ground-waters to, 78-79

Millstones, 269

Minas Geraes, Brazil, iron ores, 52-53, 162, 165, 167, 313

Mineral deposits,
classification and general features of origin, 27-59
exploration and development, 301-327
origin as a factor in economic problems, 29-31, 322-323
outcrops, 311-317
secondary concentration, 46-50, 54-57
_See also_ under Iron ores, Copper ores, etc.
zonal arrangement, 42-45

Mineral industry,
basis for popular interest in, 328
"social surplus" of, 330

Mineral lands, classification, 309-311

Mineral paints, relative position of United States, 397

Mineral provinces and epochs, 308-309

Mineral resources,
conservation, 359-382
general quantitative considerations, 60-66
international aspects, 383-404
laws relating to, 342-358
nationalization, 345-347, 375-376, 377-378, 382
political and commercial control, 65
relative position of the United States in regard to supplies, 396-400
valuation and taxation, 328-341
world movement, 383-388
world reserves, 65-66

Mineralogy, relation to economic geology, 3

"Minette" iron ores, 158, 161, 166

Mining law, 342-358

Mining methods, control of by government or owners in interests of
conservation, 355

Minnesota,
granite, 82
iron. _See_ Lake Superior iron ores, Mesabi district, etc.
manganese, 175, 177

Minnesota, taxation of iron ores, 335

Mississippi Valley, cadmium, 254
lead and zinc ores, 54-55, 108, 211-212, 214, 215-219, 308, 313

Missouri, barite, 273-274
cadmium, 254
lead, 209, 211
silica for refractories, 195
tripoli and rottenstone, 269
zinc, 214, 215, 217-218

Molybdenum ores, 185-187, 397

Monazite, 288-289, 398

Montana, arsenic, 250-251
copp