THE MINING AND QUARRY INDUSTRY 1914 35 



ores. The process, it may be explained in a word, makes use of the 

 differences of electric conductivity in the separation of minerals ; 

 inasmuch as graphite is a good conductor and mica a very poor 

 one there seems to be a basis at least for experimentation in this 

 field. 



GYPSUM 



The gypsum mines of the State were not quite so actively worked 

 last year as in the preceding season, but still yielded a large output. 

 The decrease in tonnage which was of small proportions may be 

 attributed to the poor market for calcined products which in turn 

 was influenced by the decline of building operations throughout the 

 East. The market for gypsum plasters for a time was oversupplied 

 and became almost demoralized by the competition among mills 

 for the little trade that existed. In some building centers these 

 products were offered at prices which left little or no profit to the 

 manufacturer. In view of the enormous development of the indus- 

 try that has taken place in the last few years it is but natural that 

 the production finally should reach a point where it equaled or 

 exceeded the requirements, a condition that obtained last year for 

 the first time. With the resumption of normal activity in the 

 market the industry doubtless will rapidly recover from the 

 depression. 



The production of gypsum last year was reported from four 

 counties — Onondaga, Monroe, Genesee and Erie. There are sev- 

 eral others that contain deposits, since the district extends all the 

 way from Madison county on the east to the Niagara river, but the 

 present mine localities have certain advantages as to quality of the 

 rock or for economic extraction and marketing of the materials. The 

 thickest deposits are found in the east in Onondaga, Cayuga and 

 Madison counties where they attain a maximum of from 15 to 40 

 feet. The grade is somewhat inferior, however, the gypsum being 

 intermixed with clayey and calcareous impurities and having a 

 rather dark color. These deposits consequently are not employed 

 generally for calcined plasters, but are useful as sources of agri- 

 cultural plaster. In Monroe, Genesee and Erie counties, the deposits 

 are much thinner, averaging 4 or 5 feet in most places, but have a 

 higher purity so that the rock is well adapted for practically all 

 purposes. Most of the output in these counties is calcined, but a 

 fairly large proportion is sold crude to cement manufacturers. 



The total output was 513,094 short tons or about 20,000 tons 

 less than in 191 3. The following table shows the output distributed 

 according to uses for the two years. 



