42 NEW YORK STATE MUSEUM 



down by the Buffalo Cement Co., at Buffalo several years ago 

 showed two beds of white gypsum each 4 feet thick. The upper 

 bed was encountered at 43 feet from the surface and the lower 

 one at 62 feet, with a 2 foot bed at 49 feet. An attempt to ex- 

 plore the upper bed by a vertical shaft was relinquished after meet- 

 ing a heavy flow of water and nothing has been done since toward 

 the development of the deposits. 



Chemical composition of the gypsum. Analyses of average 

 samples of the deposits from different localities recently made for 

 the State Museum, indicate that the gypsum content ranges between 

 the general limits of 64 or 65 per cent and 95 per cent. The qual- 

 ity seems to improve toward the west. The impurities are mainly 

 clay, lime and magnesia carbonates and quartz. 



12345 

 Si0 2 51 .40 2.93 4.00 8.31 



A1A, 1. 19 2.97 1.92 1.74 4.53, 



Fe,0 3 .79 -77 i-io 1. 11 1.34 



CaO 30.62 30.76 26.27 29.36 21.50 



MgO 1.20 1.53 8.29 2.81 7.20 



S0 3 43-59 43-78 33-83 35-79 30-47 



C0 2 1.02 2.80 11.02 6.38 9.50 



HsO 20.52 17.53 14.87 17.93 14-53 



99.44 100.54 100.23 99.12 97.38 

 Gypsum calculated. . 93.74 94.26 72.84 77.06 65.49 



1 Akron, Erie co. 2 Oakfield, Genesee co. 3 Garbutt, Monroe 

 co. 4-5 Lyndon, Onondaga co. Analyses are by George E. Will- 

 comb. 



Methods of extraction. The gypsum beds of the eastern section 

 are worked by quarry methods. The smaller pocket deposits have 

 been exploited only in a desultory manner, their yield from year 

 to year depending upon the local market for land plaster. More 

 systematic operations are carried on in connection with the rock 

 gypsum of Onondaga and Cayuga counties. The beds are exposed 

 along the edges of hills with a variable covering of limestone and 

 drift which is stripped off or allowed to fall into the excavation as 

 the gypsum is removed from the face. The gypsum is broken 

 down by drilling and blasting. Power drills of the percussion type 

 and hand drills are both employed. As the quarry advances into 

 the hill an increasing overburden is encountered and in the course 

 of time may become a serious obstacle to the continuation of open 

 quarry work. Operations are then either transferred to a mew 

 locality or changed to underground mining. 



In the section west of Cayuga county the gypsum is worked 

 underground, by means of an adit where the bed approaches close 

 to the surface, otherwise by a vertical shaft. This method has 



