ARGILLACEOUS LIMESTONE: CEMENT ROCK. 



327 



few pure limestone beds occur, and the material from these low-magnesia 

 beds is shipped to a neighboring cement-mill. 



Numerous analyses of the highly magnesian limestones are available, 

 from which a few typical results have been selected for insertion here. 

 Analyses of the purer limestone, used to add to the cement rock, wilL 

 be found in the table on page 329. 



TABLE 151. 

 ANALYSES OF KITTATINNY MAGNESIAN LIMESTONE.* 



From various reports of the New Jersey Geological Survey. 



1. Chandlers Island, Sussex County, N. J. 



2. Sparta, Sussex County, N. J. 



3. Asbury, Warren County, N. J. 



4. Oxford Furnace, Sussex County, N. J. 



5, 6. Clinton, Hunterdon County, N. J. 



7. Pottersville, Somerset County, N. J. 



8, 9. Peapack, N. J. 

 10. Annandale, N. J. 



While all of the above analyses are from New Jersey localities, the 

 magnesian limestone of the rest of the Lehigh district would give closely 

 similar results. 



Throughout most of the Lehigh district the practice is to mix a 

 small amount of pure limestone with a relatively large amount of the 

 "cement rock" or argillaceous limestone, in order to bring the lime 

 carbonate content up to the percentage proper for a Portland-cement 

 mixture. As above noted, all of the "cement rock" is derived from the 

 middle part of the Trenton formation, where the beds will run from 

 60 to 70 per cent of lime carbonate. The pure limestone which is re- 

 quired to bring this material up to the necessary percentage of lime 

 carbonate (75 per cent or so) is obtained either from the lower portion 

 of the Trenton itself or from certain low-magnesia beds occurring, 

 in the Kittatinny formation. 



