364 



CEMENTS, LIMES, AND PLASTERS. 



limestone. Isolated slate districts occur in Virginia, but not near 

 limestone areas. In eastern Tennessee and northwestern Georgia, 

 however, roofing slates and non-magnesian limestones occur in close 

 proximity; and in the Georgia slate district a Portland-cement plant 

 is already in operation. West of the Mississippi, good slates are worked 

 more or less extensively in Minnesota, Arkansas, Utah, and California. 

 Composition of slates. The composition of a large series of Ameri- 

 can roofing slates from various localities is given in Table 164. 



TABLE 164 

 ANALYSES OF AMERICAN ROOFING SLATES. 



1. Monson, Maine. 

 2. 



3. Lancaster, Mass. 



4. Hamburg, N. Y. 



5. West Pawlet, Vt. 



* Carbonate. 



6. Pawlet, Vt. 



7. Poulteney, N. Y. 



8. Raceville, N. Y. 



9. Bangor, Pa. 



10. Peach Bottom, Pa.-Md. belt. 



11. Peach Bottom, Pa.-Md. belt. 



12. Martinsburg, W. Va. 



13. Arvonia, Va. 



14. Rockmart, Ga. 



TABLE 165. 

 COMPOSITION OF AMERICAN ROOFING SLATES. 



