salt, 298
sulphur, 110

Lower California, copper, 201
magnesite, 191-192

Luxemburg, coal situation under Peace Treaty, 401
iron ores, 160-162, 163
_See also_ under Lorraine, iron ores

Madagascar, corundum, 268
graphite, 280-282

Magmatic segregation, mineral deposits thus formed, 34-35, 59

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

Magnesite, 191-193, 397

Magnetic surveys in tracing mineral ledges, 317-318

Magnetite deposits, 34, 171, 191, 317-318

Maine, feldspar, 86
granite, 82
tourmaline, 293

Malay States, tin, 260-261
tungsten, 183

Manchuria, iron, 160

Mandatory countries, exploitation of minerals in, 390-391

Manganese ores, 47, 55, 173-178, 314, 386, 398

Mansfield shales, Germany, copper ores, 9, 52, 206

Mantle rock, 22

Mapimi, Mexico, arsenic production, 250

Marble, 83, 89-90

Marbut, Curtis F., 95

Marl, 83

Marquette district, Michigan, iron ore outcrops, 312

Maryland, diatomaceous earth, 269
serpentine, 83

Marysville, Utah, alunite deposits, 114

Mashing, 25-26

Massachusetts, granite, 82
serpentine, 83

McCoy, A. W., 142

Mead, Daniel W., 69, 77-78

Mead, W. J., 245

Mead, W. J., and Leith, C. K., 45

Mehl, M. G., 144

Menominee district, Michigan, iron ore outcrops, 312

Mercury ores, 40, 255-260, 398

Mesabi district, Minnesota, concentration of siliceous iron ores, 156
exploration for iron ores, 313, 318, 324, 325

Mesopotamia, petroleum, 128-130, 137, 391

Mesothorium, 288

Metallogenic provinces and epochs, 308-309

Metamorphic cycle and its relation to classification of mineral
deposits, 27-28

"Metamorphic rocks," defined, 27

Metamorphism, relation to economic geology, 10
use of principles of in exploration
for mineral deposits, 319-320
_See also_ Katamorphism, Anamorphism, Contact metamorphism,
Dynamic metamorphism, Weathering, etc.

Metasomatic replacement, 24

Metcalf-Morenci district, Arizona, copper ores, 38, 198

Meteoric waters, influence of in deposition of ore deposits, 25, 41-42

Mexico,
antimony, 247-248
arsenic, 250
cement, 87
copper, 197-198, 201, 203
gold, 222
graphite, 280-282, 283
lead, 210-211
magnesite, 191-192
mercury, 256, 258
molybdenum, 186
natural gas, 151
petroleum, 128