32 NEW YORK STATE MUSEUM 



or mined along the outcrop from Madison county westward. 

 The SaHna 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. 



Most 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 wdth them at a very low 

 angle to the south. They afford a practically inexhaustible 

 supply. Their greatest thickness along the outcrop is in Onon- 

 daga 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 New York 

 has been due to the establishment of plants for the manufacture 

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

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

 Formerly the principal outlet for the mineral was in agriculture 

 which still affords a small market for the ground product. 

 Another use that has become quite important is in the Portland 

 cement trade; a considerable proportion of the gypsum listed in 

 the accompanying table as sold in crude state is shipped to 

 points in Pennsylvania and elsewhere for admixture with Port- 

 land 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, 

 besides a small proportion of organic matter which is the prin- 

 cipal coloring agent. In calcination the organic substances are 

 broken up or driven oif. The impurities on the average amount 

 to from 5 to 15 per cent of the total. 



The manufacture of calcined plasters is carried on in Syracuse 

 and vicinity, at Wheatland and Garbutt, Monroe co., and at 

 Oakfield, Genesee co. 



Production and trade. With the exception of the last three 

 months of the year, the demand for gypsum and gypsum mater- 

 ials was active, stimulating a largely increased output. The 

 quantity of gypsum mined or quarried during the year was 



