2 14 Bulletin of Laboratories of Denisofi University [Voi. xii 



from the decay of the quartzite. So far as mining developments 

 have been made in the area, the ocher has nearly equal occur- 

 rence in the fresh and in the decayed quartzite. At every 

 point examined, its position in the residual clays is in all re- 

 spects similar to that in the hard and fresh rock. Its occur- 

 rence in the fresh and in the altered rock can best be described 

 separately. 



Occttrrence in the Fresh Rock. — Abundant opportunity is af- 

 forded for studying the mode of occurrence of the ocher in the 

 fresh rock over many parts of the area, from the good natural 

 exposures of the rock. (See Figs. 4, 5 and 6.) For the study 

 of the ocher in its relations to the fresh rock, the best section 

 is at the wooden bridge over the Etowah river, two miles south- 

 east of Cartersville, where the river has cut across one of the 

 quartzite ridges and where extensive mining has been done by 

 the Georgia Peruvian Ocher Company. Here the quartzite has 

 been extensively crushed and shattered from compression, so 

 that it is difficult to determine the original bedding of the rock 



(Fig- 4)- 



Concerning the occurrence of the ocher at this locality, 



Doctor Hayes says :' "The ocher forms a series of extremely 

 irregular branching veins, which intersect this shattered quartz- 

 ite without any apparent system. They frequently expand into 

 bodies of considerable size ; and when the ocher is removed, 

 rooms from 6 to 10 ft. in diameter are sometimes left, connected 

 by narrow winding passages. The mining of the ocher has left 

 the point of the ridge completely honey-combed with these 

 irregular passages and rooms. 



"The contact between the ocher and the inclosing quartz- 

 ite is never sharp and distinct, but always shows a more or less 

 gradual transition from the hard vitreous quartzite, to the soft 

 ore which may be easily crushed between the fingers. The 

 quartzite first becomes stained a light yellow, and loses its com- 

 pact, close-grained texture. This phase passes into a second, 

 in which the rock is perceptibly porous, having a rough fracture 



' Trans., xxx., 415--416. 



