CLAYS, SHALES, AND SLATES. 



365 



Slates used in cement-manufacture. Only one American Portland- 

 cement plant is at present using roofing slate as one of its raw mate- 

 rials, and this plant is of quite recent construction. It is that of the 

 Southern States Portland Cement Company, and is located about half 

 a mile east of the village of Rockmart, Polk County, Ga. The Port- 

 land cement manufactured here is made from a mixture of pure lime- 

 stone and slate, both of which materials occur in the immediate vicinity 

 of the plant. 



Hard blue slates, which have been extensively quarried for struc- 

 tural purposes, outcrop on the hills south of Rockmart. These slates 

 are of Ordovician age and have been described as the "Rockmart 

 slates" by Hayes. East of the town the surface rock is the "Chicka- 

 mauga limestone," which here contains beds of pure non-magnesian 

 limestone which have been quarried at several points in the vicinity 

 and burned into lime. 



The cement company purchased the property of the old Georgia 

 Slate Company, about half a mile southwest of Rockmart, and car- 

 ried on extensive operations with the diamond-drill. The intention 

 was to quarry the slate, sell as slate the portions best suited for that 

 use, and utilize the scrap and waste in the manufacture of cement. 

 The quarries from which the limestone is obtained are located half a 

 mile east of town, near the mill. The president of the cement com- 

 pany is Mr. W. F. Cowhan, who is also connected with the Peninsular 

 Portland Cement Company, of Jackson, Mich., and the National Port- 

 land Cement Company, of Durham, Ontario. 



TABLE 166. 

 ANALYSES OF SLATE USED FOR PORTLAND CEMENT, ROCKMART, GA. 



1. J. F. Davis, analyst. Privately communicated. 



2. Slocum and Vandeventer, analysts. 18th Ann. Rep. U. S. Geol. Survey, pt. 5. 



