ASSIFICATION OF MINERAL LANDS 309

OUTCROPS OF MINERAL DEPOSITS 311
Some illustrative cases 312
Topography and climate as aids in searching for mineral
outcrops 314
Size and depth of ore bodies as determined from outcrops 315
The use of placers in tracing mineral outcrops 316
The use of magnetic surveys in tracing mineral ledges 317

THE USE OF ELECTRICAL CONDUCTIVITY AND OTHER QUALITIES OF
ROCKS IN EXPLORATION 319

THE USE OF STRUCTURE AND METAMORPHISM IN EXPLORATION 319

DRILLING IN EXPLORATION 320

QUANTITATIVE ASPECTS OF GEOLOGIC EXPLORATION 321

ORIGIN OF MINERAL DEPOSITS AS A FACTOR IN EXPLORATION 322

LAKE SUPERIOR IRON ORE EXPLORATION AS AN ILLUSTRATION 323

DEVELOPMENT AND EXPLOITATION OF MINERAL DEPOSITS 326

CHAPTER XV. VALUATION AND TAXATION OF MINERAL
RESOURCES 328

POPULAR CONCEPTION OF MINERAL VALUATION 328

VALUATION AND TAXATION OF MINES 329
Intrinsic and extrinsic factors in valuation 329
Values of mineral deposits not often established by
market transfers 331
The ad valorem method of valuation 331
Other methods of mineral valuation and taxation 335

GENERAL COMMENTS ON TAXATION OF MINERAL RESOURCES 338

CHAPTER XVI. LAWS RELATING TO MINERAL RESOURCES 342

I. LAWS RELATING TO OWNERSHIP AND CONTROL OF MINERAL
RESOURCES 342
On alienated lands 343
On the public domain 344
Nationalization of mineral resources 345
Effect of ownership laws on exploration 347
Use of geology in relation to ownership laws 349

II. LAWS RELATING TO EXTRACTION OF MINERAL RESOURCES 355

III. LAWS RE