150 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 

 Sani])le 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 Ijccn done in duplicate and the average given) 



Sample I A B Average 



Water 14.96 14.90 14-93 



Silica 20.93 20.94 20.94 



Alumina 5.14 5.07 5.10 



I'erric 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 49-25 49-37 



Chlorine Trace Trace Trace 



100.20 99-93 100.06 



.Va ////■/(' 2 A B Average 



Water 19.83 1992 19-87 



Silica 0.34 0.37 0.36 



Alumina , 0.00 o.oi o.oi 



Ferric oxid 0.36 0.38 0.37 



Calcium carbonate 4 . 29 4.19 4 . 24 



]\Iagnesium carbonate 1.90 1.90 1.90 



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 i . 19 1-26 i .22 



Calcium sulfate 75-74 75-82 75-78 



99.96 100.22 100.09 



