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NEW YORK STATE MUSEUM 



samples were taken from the commonest expressions, not necessarily 

 from the purest. Sample i is somewhat out of the ordinary and is 

 not an average. Samples 2 and 3 are fair averages of the predomi- 

 nant rock and there remains a very substantial opportunity of acquir- 

 ing a better grade by selection. These analyses are here appended. 



ANALYSES OF GYPSUM FROM GRINDSTONE ISLAND 

 By E. W. Morley 

 Sample I Compact gray, with red and green mottles 



2 Coarse crystalline, with alternating black and white 



bands 



3 Darker, with more finely alternating black and white 



bands 

 (Each sample has been done in duplicate and the average given) 



Sample 1 A B Average 



Water 14-96 14.90 14-93 



Silica 20.93 20.94 20.94 



Alumina 5.14 5.07 5.10 



Ferric oxid 2.20 2.21 2.21 



Calcium carbonate 2 . 98 3 . 07 3 . 02 



Magnesium carbonate 4-49 (4-49) 4-49 



Calcium sulfate 49-50 49- 2 5 49-37 



Chlorine Trace Trace Trace 



100.20 99-93 100.06 



Sample 2 A B Average 



Water 1983 1992 19-87 



Silica 0.34 0.37 0.36 



Alumina 0.00 0.01 0.01 



Ferric oxid 0.36 0.38 0.37 



Calcium carbonate 4 • 29 4 • *9 4 • 24 



Magnesium carbonate 1 .90 1 -90 1 -9° 



Calcium sulfate 73-34 73-44 73-39 



100.06 100.21 100.14 



Sample 3 A B Average 



Water 20.00 20.06 20.03 



Silica 0.38 0.43 0.41 



Alumina 0.29 0.27 0.28 



Ferric oxid 0.32 0.32 0.32 



Calcium carbonate 2.04 2.06 2.05 



Magnesium carbonate 1.19 1.26 1.22 



Calcium sulfate 75-74 75-82 75 . 78 



99.96 100.22 100.09 



