ARGILLACEOUS LIMESTONE: CEMENT ROCK. 



329 



TABLE 152. 

 ANALYSES OF HIGHLY CLAYEY LIMESTONES: 



'CEMENT ROCK' 



TABLE 153. 

 ANALYSES OF PURE LIMESTONES USED FOR MIXING WITH CEMENT ROCK. 



its limestone quarry material running as low as 85 per. cent of lime 

 .carbonate is often used. 



Quarry practice. In most of the cement-rock quarries of the 

 Lehigh district the rock dips from 15 to 25, usually to the northwest. 

 At a few quarries, particularly in New Jersey, the dip is much steeper. 

 The quarries are opened preferably on a side-hill, and the overlying 

 stripping, which consists of soil and weathered rock, is removed by 

 scrapers or shoveling. The quarry of the Lawrence Cement Company 

 has been extended in its lower levels so as to give a tunnel through 

 which the material is hoisted to the mill. Several other quarries have 



