64 PHYSIOGRAPHY. 



Bituminous Coal Black Manganese. 



ten cents the bushel ; and at Pittsburg, where it is most abundant, its 

 price is six cents the bushel. According to Maclure, the independent 

 coal formation extends from the waters of the Ohio to the waters of the 

 Tombigbee. The coal of this region is chiefly a very pure slate coal ; 

 and is often beautifully tarnished with the richest iridescence. At some 

 places upon the Ohio, however, extensive deposits of the purest pitch 

 coal are found. The secondary region of the Connecticut river affords 

 occasionally traces of Bituminous Coal, not only in its sandstones and 

 slates, but in its trap ; but is no where likely to be found in sufficient 

 quantity to be explored. 



5. The important uses of this species for fuel are well known. Can- 

 nel coal and jet are wrought for ornamental purposes. 



BLACK MANGANESE. Pyramidal Manga- 

 nese-Ore. MOHS. 



Primary form. Octahedron with a square base. P on 

 P"=]17 30'. 



Secondary form. 



Fig. 60. 



a on a - 139 56' 



Cleavage, parallel to the base of the primary form per- 

 fect ; less distinct and interrupted parallel with the octahe- 

 dral faces. 



Fracture uneven. 



Lustre imperfect metallic. Color brownish black, 

 Streak dark reddish or chesnut-brown. Opake, 

 * 



