Sulphur, 99-100, 109-111, 397

Sulphur Bank Springs, California, deposition of mercury by hot waters,
259

Supergene ores, use of term, 32, 33, 48

Surface water supplies, 76-78

Surface waters, application of geology to use of, 414
relation to excavation and construction, 78-79

Sweden, cement, 87
iron, 154, 155, 156, 158, 160, 162, 163, 171
manganese, 176
phosphate from Thomas slag, 104
zinc, 214
_See also_ Scandinavia.

Switzerland, cement, 87
nitrogen fixation plants, 102

Syngenetic ore deposits, use of term, 32, 34, 51

Taconite, 167

Talc and soapstone, 299-300, 397

Tankage, use of phosphate content, 104

Tariffs, proposed, on mineral resources, 175-176, 179, 184, 192, 248,
257-258

Tariffs and duties, anti-conservational effect of, 362-363, 366, 375,
376, 393-394

Tasmania, bismuth, 252
platinum, 238
zinc, 214

Taxation of mineral resources, 1, 335-341

Tennessee, barite, 273
bauxite, 243, 245
copper, 204
flint linings, 269
marble, 83
petroleum, 132, 133
phosphates, 105, 107
zinc, 54-55, 216, 219

Terlingua district, Texas, mercury, 257, 259

Texas, asphalt and bitumen, 152
coal, 117
fuller's earth, 279
graphite, 281
gypsum, 284
mercury, 256, 257, 259
natural gas, 151
petroleum, 132, 133, 135, 148
salt, 298
sulphur, 110

Thermal metamorphism. _See_ Contact metamorphism.

Thermal waters, 72

Thibet, borax, 275, 276

Thomas process of steel making, 158, 161
use of slag for phosphate content, 104, 106

Tin ores, 36-50, 51, 260-263, 307, 322, 386, 392, 398

Tintic, Utah, silver ores, 39, 42, 235, 251, 253

Titaniferous magnetites, 34, 171, 191

Titanium ores, 190-191, 398

Tonopah, Nevada, gold silver ores, 38, 234, 236-237, 308

Topographic cycle, description of, 6

Topography, relation to mineral deposits, 7-9, 314-315
relation to rock structures, 7

Tourmaline, 290, 293

Training in economic geology, 420-428

Transvaal, Africa, asbestos, 272
diamonds, 291
gold, 222, 223-225, 228

Trap-rock, 82

Travertine, 83

Treadwell Mine, Alaska, gold ores, 229

Trenches, military, application of geology to, 408, 410-411

Trinidad, asphalt, 152, 153
petroleum, 128

Tripoli, 267, 269, 398

Tungsten ores, 51, 182-185, 386, 398

Tuni