194 Bulletin of Laboratories of Denison University. [Voi.xti 



the source, on decay, of the workable deposits of manganese 

 in the form of the oxide. In several localities the oxide is 

 found, in place, in the fresh rock, but, usually, it is a second- 

 ary product inclosed in the residual clays, similar to the ores 

 of the Paleozoic area. The manganese of both the Crystalline 

 and Paleozoic areas of Georgia include only the oxides ot 

 the metal. 



Extent of the Work and Location of the Deposits. — More 

 or less prospecting work for manganese-ores has been done in 

 a number of counties in the Crystalline area. The test-work 

 has been sufficient in most cases to indicate that workable de- 

 posits of the ore do not exist, although small shipments of the 

 ore have been made from a number of the openings in different 

 counties. 



The localities in which prospecting work has been done for 

 manganese are widely separated and are scattered over various 

 parts of the area which bear no apparent geological relation- 

 ship to each other. The deposits are not associated with any 

 particular type of rock, but are found in association with several 

 widely different mineralogical types. 



The counties in which manganese has been worked or test- 

 ed in the Crystalline area are Murray, Fannin, Towns, Chero- 

 kee, Haralson, Paulding, Habersham and Hart. See map (Fig. 

 i), which shows the distribution of the ore-deposits. 



Genesis of the Ores in the Crytalline Arra. 



Numerous openings made for manganese in different parts 

 of the Crystalline area afforded opportunity for tracing the 

 formation of the manganese oxides from several of the man- 

 ganese-bearing silicates. Of these a manganiferous garnet and 

 mica showed the formation of the oxide from the original sili- 

 cate in both a partial and complete stage of decomposition. In 

 each case the early stage was indicated by the original mineral 

 being irregularly coated and spotted from decay by a mixture 

 of the oxides of manganese and iron. The final stage showed 

 the almost complete destruction of the original mineral, and its 

 place filled by the black amorphous oxides of manganese and 



