70 



KEMP'S ORE DEPOSITS. 



The limonite is in cellular lumps, in pipes, pots, and various imita- 

 tive forms which often have a beautiful luster. The hollow masses 

 have in general resulted form the filling of reticulated cracks in 

 shattered rock. The ore thus deposits around the cores of country 

 rock, which afterward are removed, leaving a hollow shell or geode. 

 (See Tenth Census, Vol. XV., pp. 275, 369, 370.) 



2.01.11. Reserving the Siluro-Cambrian limonites for a subtype 

 the ore bodies are described in order from east to west, taking up 

 first the Alleghany region, then the Mississippi Valley, and lastly 





FIG. 8. Section of the Hurst limonite bank, Wythe County, Virginia, 



illustrating the replacement of shattered limestone with limonite 



and the formation of geodes of ore. After E, R, Benton, 



Tenth Census, Vol. XV., p. 275. 



the Rocky Mountains. The limonites of New England and New 

 York belong in the subsequent subtype, as do those of eastern 

 Pennsylvania and the more important ones in Virginia, Tennessee, 

 Georgia, and Alabama. In central and western Pennsylvania, 

 however, not a small amount is obtained from the higher lying 

 terranes. The Hudson River slates furnish small amounts in 

 Franklin County, which are thought by McCreath to have resulted 

 from the alteration of nodules of pyrites. (Second Penn. Geol. Sur- 

 vey, MS, p. x.) The Medina sandstones contain highly ferrugi- 

 nous portions in Huntingdon County. (McCreath, Second Penn. 

 l. Survey, MM, p. 198.) The Lower Helderburg and Oriskany 



