264 



NEW YORK STATE MUSEUM 



much greater than is indicated by the table, since large quantities 

 in addition are made by local plants from imported materials. Of 

 the total product of crude gypsum last year, about two-thirds was 

 converted into calcined plasters (plaster of paris, stucco and wall 

 plasters) by the companies who operated the mines, and the remain- 

 ing third was sold in crude form, principally to portland cement 

 mills, or ground to land plaster. 



Production of gypsum in New York 





1 



915 



' 



916 



MATERIAL 



SHORT 

 TONS 



VALUE 



SHORT 

 TONS 



VALUE 



Total output, crude 



Sold crude 



5l6 002 



162 686 



6 536 



292 344 





579 827 

 188 077 



7 169 

 311 264 





$241 511 



13 486 



I 006 203 



$273 322 

 18 710 



1 167 555 



Ground for land plaster .... 

 Wall plaster, etc., made. . . . 



Total 





$1 26l 200 





$1 459 587 







The production in 191 6 was reported from five counties (Onon- 

 daga, Cayuga, Monroe, Genesee and Erie) situated in central and 

 western New York along the belt of Salina strata which hold the 

 gypsum. The Salina beds are mostly shales, with limestones near 

 the top, inclosing beds of rock salt and massive gypsum. The great- 

 est thickness of the formation is in Onondaga and Cayuga counties 

 where the beds altogether measure 1000 feet or more from the base 

 to the top. Here also occur the heaviest layers of gypsum, ranging 

 from 20 to 60 feet, the latter thickness being, attained in the vicinity 

 of Fayetteville and Jamesville, Onondaga county. The gypsum in 

 the western section seldom exceeds 6 or 8 feet in thickness. 



There is a great difference in the grade of the gypsum that is 

 obtainable in the different deposits. The percentage of hydrated 

 calcium sulphate, or gypsum substance, ranges from 65 to 70 per 

 cent in the more impure sorts to 95 per cent in the best rock. The 

 impurities consist of clayey matter and the carbonates of lime and 

 magnesia. The variation is not altogether without rule, for it can 

 be stated in general that the grade improves progressively from 

 east to west, the best quality of rock being found in Genesee and 

 Erie counties on the extreme west end of the belt, while on the east 

 end in Madison, Onondaga and Cayuga counties the average 



