VI. NICKEL, BY C. S. CORBETT 129 VII. TUNGSTEN, BY FRANK L. HESS 142 VIII. VANADIUM, BY R. B. MOORE 163 IX. ANTIMONY, BY H. G. FERGUSON AND D. A. HALL 172 X. MOLYBDENUM, BY R. B. MOORE 191 XI. RADIUM AND URANIUM, BY R. A. F. PENROSE, JR. 201 XII. ZIRCONIUM, BY H. C. MORRIS 209 XIII. MONAZITE, THORIUM, AND MESOTHORIUM, BY R. B. MOORE 216 XIV. COPPER, BY F. W. PAINE 223 XV. LEAD, BY FREDERICK B. HYDER 261 XVI. ZINC, BY FREDERICK B. HYDER 294 XVII. TIN, BY JAMES M. HILL 317 XVIII. MERCURY, BY F. L. RANSOME 337 XIX. BAUXITE AND ALUMINUM, BY JAMES M. HILL 349 XX. EMERY AND CORUNDUM, BY FRANK J. KATZ 356 XXI. MAGNESITE, BY R. W. STONE 363 XXII. GRAPHITE, BY H. G. FERGUSON, FRANK F. GROUT, AND GEORGE D. DUB 372 XXIII. MICA, BY DURAND A. HALL 380 XXIV. ASBESTOS, BY OLIVER BOWLES 388 XXV. PHOSPHATE ROCK, BY R. W. STONE 402 XXVI. POTASH, BY HOYT S. GALE AND A. W. STOCKETT 411 XXVII. NITROGEN, BY CHESTER G. GILBERT 421 XXVIII. PYRITE AND SULPHUR, BY A. G. WHITE 447 XXIX. GOLD, BY JOHN E. ORCHARD 462 XXX. SILVER, BY F. W. PAINE 495 XXXI. PLATINUM, BY JAMES M. HILL 506 XXXII. WHO OWNS THE EARTH? BY J. E. SPURR 522 POLITICAL AND COMMERCIAL GEOLOGY AND THE WORLD’S MINERAL RESOURCES CHAPTER I PETROLEUM BY JOHN D. NORTHROP[1] [1] In this article, prepared in June, 1918, by Mr. Northrop, have been incorporated certain notes and additions; as, for example, information furnished by E. Russell Lloyd, of the United States Geological Survey; A. G. White and W. E. Perdue, of the Bureau of Mines, and others. (J. E. S.) INTRODUCTION BY J. E. SPURR