336 REVIEWS 



The main facts of the occurrence and character of the ore and the associated 

 rocks are as follows: 



1. The iron ore occurs in tabular bodies at the contact of the porphyry 

 and the Madison limestone. The ore bodies range in width from 5 to 60 feet, 

 and average about 20 feet. 



2. The ore is the result of the replacement of the limestone, as shown by 

 its much more imeven contact surface against the limestone and by the reten- 

 tion here and there in the ore body of the banding of the limestone and of 

 parts of the limestone itself. 



3. Where the contact is inclined the hematite is more commonly found 

 where the limestone is the footwaU. 



4. The ore is a compact gray or reddish-gray hematite. It contains in 

 places enough magnetite to make it react to the magnet. It is not to any 

 large degree limonitic at the surface. At the one point where any considerable 

 depth has been reached (125 feet, on the Snowbird claim) the ore contains a 

 little pyrite and chalcopyrite. 



The limestone at the contact with the porphyry is usually altered to a 

 yellowish, finely crystalhne marble. No contact sihcates were seen except a 

 small amount of wollastonite in the rock taken from the tunnel on the Snowbird 

 claim [pp. 90 and 91]. 



E. S. B. 



Gypsum in igig. By R. W. Stone. Mineral Resources of the 

 United States, 1919. Part II, pp. 99-113. 



The gypsum industry in 19 19 showed a slight recovery from the low 

 level of production touched in 1918. The report gives the usual statis- 

 tical data, the only unusual feature being a discussion by Dr. WiUiam 

 Crocker, professor of plant physiology at the University of Chicago, of 

 "Agricultural Gypsum and Its Uses." 



Eighty years ago land plaster was one of the most used of fertilizers, and 

 there are indications that it wUl again come into general use. 



There are four main uses of this substance in agriculture: As a source of 

 sulphur for alfalfa, red clover, or other crops of high sulphur requirement, and 

 for combination with ground-rock phosphate as a substitute for acid phosphate; 

 as a preserver of manure; as a soil stimulant; and as an amendment for black 

 alkali [p. 109]. 



E. S. B. 



