of the Bocks of the Coal Formation. 



143 



100-102 



No. 3. Coarse Coal. — Sp. gr. 1-269 ; fracture slaty ; lies imme- 

 diately over the good coal ; and the bed varies from two to six inches 

 in thickness. It contains a large amount of iron pyrites, and is put 

 to no useful purpose. 



Composition. 



100000 



