620 MINERALS YEARBOOK

 Imported crude gypsum, mainly from Canada, was reported by importers at
$0.93 per short ton for 1932.
 Development of new uses.—Considerable interest has been shown during
the past few years in utilization of the physical properties of anhydrite
or the calcium sulphate which is its essential constituent. Recent research
on the use of .anhydrite (the anhydrous foi~m of gypsum) in the manufacture
of commercial plasters has had encouraging results. The resulting plasters
are reported to compare favorably with many of thebetter grades of gypsum
plasters now on the market as regards "setting" qualities and tensile strength.2
They have greateib density than gypsum plasters, are strong, and easily worked,
and promise to be cheaper in that they do not require calcination, the most
costly step in the manufacture of gypsum plasters. Moreover, they may be
used as a final or finishing coat on walls, for which purpose only lime plasters,
have hitherto been considered suitable.
 Anhydrite has replaced gypsum to a great extent in the fertilizer industry,
some 30,000 tons of this material being imported into the South Atlantic
States from Canada for fertilizing peanuts and as a constituent in some commercial
fertiizei~'s,
 Recent investigations in the United States and elsewhere have indicated,
that as much as 50 percent of anhydrite can be used with gypsum as a retarder
in portland cement.
 Considerable interest is being evidenced in the possible manufacture of
sulphuric acid and the conversion of ammonia to sulphate by gypsum upon the
completion of the Boulder Dam.3 Both processes are in commercial use to a
great extent in Germany and to a smaller degree in England. It has been estimated
that there is enough gypsum within a 50-mile radius of the dam to supply
the entire Pacific coast market for at least 50 years.
 A new method of preparing gypsum plaster employs a single mill which completes
in. one .operation the drying of the raw gypsum, its conversion into plaster
of paris, fine grinding, and pneumatic delivery.' Among the advantages reported
for this system are an increase in the speed of calcination by constant removal
of the moisture-laden air layer that otherwise accumulates above the calcining
rock, a continuous rather than intermittent process of fabrication, and installation
and operating costs that may be lower than in present plants.

PRODUCTION AND SALES

 Crude gypsum.—The sharp curtailment in the production of crude gypsum
in the United States in 1932 resulted in a mined output of 1,355,219 short
tons, a decrease of 1,203,798 tons, or 47 percent, as compared with 1931.
The number of operators reporting in 1932 was 53, or 1 less than in 1931.
 New York State continued to maintain its position as the leadmg producer
of gypsum, but like most other States showed a decrease in 1932. Nine producers
reported 347,153 tons, or 26 percent of the total output during the year.
Other important States in the production of crude gypsum in 1932 in order
of importance were Michigan,
 2 Chemical Age, Some New Uses for Anhydrite: vol. 27, no. 696, Oct. 29,
1932, p. 406.
 Carpenter, J. A., and Smith, A. M., Electrochemical Industries at Hoover
Dam: Mm. Rev. (Salt Lake) vol. 34, no. 37, Sept. 13, 1932, pp. 7—10.
 4Laeger, Horst, Combined Process for Burning Stucco Gypsum: Tonindustrie-Ztg.,
vol. 56~ Mare 10,
1932, pp. 293-294.