VI CONTENTS
Part III. Nonmetals—Continued Page
  Sand and gravel, by H. H. Hughes and E. R. Phiffips 603
  Gypsum, by R. M. Santmyers 617
  Lime, by Paul Hatmaker and A. T. Coons 629
  Clay, by R. H. Kudlich and K. V. Herlihy 639
  Abrasive materials, by Paul Hatmaker and A. E. Davis 647
  Sulphur and pyrites, by R. H. Ridgway and A. W. Mitchell 669
  Salt, bromine, calcium chloride, and iodine, by A. T. Coons 687
  Phosphate rock, by Bertrand L. Johnson 701
  Fuller's earth, by W. W. Adams and C. Galiher 709
  Talc and ground soapstone, by Alden H. Emery and B. H. Stoddarth  715
  Fluorspar and cryolite, by H. W. Davis 723
  Feldspar, by H. 0. Rogers and C. Galiher 735
  Asbestos, by Oliver Bowles and B. H. Stoddard 745
  Barite and barium products, by R. M. Santmyers and B. . Stoddard_ 753
  Potash, by J. H. Hedges 763
  Magnesium and its compounds, by E. P. Partridge and A. E. Davis.  777
  Mica, by F. W. Horton and B. H. Stoddard 787
   Natural sodiem compounds and boron minerals, by A. T. Coons - -  795
   Precious *and semiprecious stones (gem minerals), by M. W. von
     Bernewitz 799
Part IV. Mine safety:
   Safety in mining in 1932, by D. Harrington 809

ILLUSTRATIONS
Fig.
 1. Quantity-production cycles of certain important mineral commodities
 -  in the United States and the world, 1921—32 1
 2. Salient features of the copper industry, 1910—32 29
 3. Trends in production, consumption, stocks, and prices of primary
   lead in the United States, 1926—32 53
 4. Trends in the United States zinc industry, 1900—1932 67
 5. Production and price trends of the principal lead and zinc pigments,
   1915—32 88
 6. Trends in production of iron ore, pig iron, and steel in the United
   States, 1880—1932 178
 7. Trends in prices of iron ore, pig iron, finished steel, and steel scrap_
- -  179
 8. Trends of bauxite production for the United States and for the world
   over two decades compared with shipments into the United States
   and domestic exports 208
 9. Primary aluminum produced in the United States and in the world,
   1913—32, compared with imports into the United States, and
   with domestic consumption, exports, secondary production, and
   the trend of the average New York quoted price (no. 1 virgin 98—99
   percent) 209
 10. Location of mercury mines and prospects, western United States - - 
229
 11. Trends in production, imports, stocks, and prices of tin, 1901—32
283
 12. Trends in consumption, price, and domestic shipments of chromite
   in the United States, 1923—32 299
 13. Average price per troy ounce of platinum and allied metals at New
   York, January 1931 to April 1933 340
 14. Outstanding trends in the nickel industry, 1901—1932 370
 15. Current trends of production, stocks, and prices of bituminous coal,
   1927—32 383
 16. Monthly movement of bituminous coal in the major channels of distri
   bution, 1931—32 388
 17. Monthly production of bituminous coal in selected fields, 1931—32.
- -  391
 18. Trend of bituminous-coal production and of mine capacity in the
   United States, 1899—1932 392
 19. Tonnage of bituminous coal absorbed by the principal branches of
   consumption, 1917—32 395
 20. Relative rate of growth of annual supply of coal, oil and gas, and
   water power in the United States, 1870—1932 397
 21. Trends in fuel efficiency in the United States, 1917—32 401
 22. Twenty-two years' exports of bituminous coal to (1) Canada and
   Mexico, (2) the Caribbean, and (3) "overseas" destinations 404
 23. Tonnage of bituminous coal loaded mechanically, classified by types
   of machines, 1926—32 405