30 .\i:\\ VLiKK STATK MLSliUM 



esee and l-^ric counties. The gypsum is associated with the Salina 

 forniatiuii, which carries the rock salt beds, and is ciuarricd or 

 mined along the outcrop from Madison county westward. The 

 Salina formation can be traced to the east into Albany county but 

 with such diminishing thickness as to preclude the occurrence of 

 workable gypsum deposits in that section. 



^lost of the workings are situated near the southern edge of 

 the belt occupied by the Salina beds. The gypsum occurs below 

 the Bertie waterlime, which marks the top of the formation, and 

 above the salt horizon. Its beds are regularly disposed with respect 

 to the inclosing rocks, dipping with them at a very low angle to 

 the south. They aflford a practically inexhaustible supply. Their 

 greatest thickness along the outcrop is in Onondaga county where 

 as much as 60 feet have been found, divided into several layers. 

 In the western part of the State the beds range from 4 to 8 feet 

 thick. Many of the borings for salt have encountered gypsum, 

 showing its continuation for long distances to the south along the 

 dip of the strata. 



The present extensive utilization of gypsum in Xew York has 

 been due to the establishment of plants for the manufacture c 

 plaster of paris, stucco, wall plasters, etc., a branch of the industi^ 

 that has grown to large proportions in the last decade. Formerly 

 the principal outlet for the mineral was in agriculture, which still 

 afifords a small market for the ground product. Another use 

 that has become quite important is in the portland cement trad 

 a considerable proportion of the gypsum listed in the accompan . 

 ing table as sold in crude state is shipped to points in Pennsyl- 

 vania and elsewhere for admixture with portland cement. 



The gypsum rock as found in New York has a gray or drab 

 color. It contains a varying amount of impurities in the form 

 of lime and magnesia carbonates, clay and silica or quartz, be- 

 sides a small proportion of organic matter which is the principal 

 coloring agent. In calcination the organic substances are broken 

 up or driven off. The impurities on the average amount to from 

 5 to 15 per cent of the total. 



Manufacture. ]\Iost of the gypsum that is mined or quarried 

 in the State undergoes some kind of preparation before shipment. 

 In the case of the material sold to portland cement manufactur- 

 ers, however, a portion is shipped in lump form to be later crushed 

 at the cement works and mixed with the clinker before grinding. 

 A part of the gypsum, also, is crushed at the mines and shipped 

 in bags. A very small quantity is sold in calcined condition to 



