Art. IX.] Watson, Manganese Ore-Deposits of Geo gia. 193 



small grains and crystals of manganiferous magnetite and sep- 

 arate grains of manganese oxide, and in places the rock is 

 pyritiferous. The manganese is mostly concentrated along the 

 contact between the quartzite and schist, but contained mostly 

 in the quartzite as massive ore carrying usually much iron, which 

 at times almost totally replaces the manganese. (See Figs. 16 

 and 17.) Between the two extremes of manganese-ore contain- 

 ing a little iron and iron-ore with a little manganese, all degrees 

 of admixture of the two oxides occur. 



The nodular type of ore similar to that of the Cartersville 

 district is, perhaps, best developed in the manganese-deposits 

 occurring within the southern limits of the town of Blue Ridge, 

 in Fannin county. (See Fig. 18.) Here the manganese is 

 found in the residual clays derived from the decay of mica- 

 schist near the margin of a narrow band of jasper-like quartz, 

 which cuts the schist in an approximate north-south direc- 

 tion. The manganese is distributed through the clays as 

 gravel, nodules and larger masses in nests or small pockets 

 and stringers. The ore contains much siliceous impurity, and 

 is in intimate relation with iron-ore, much of which has been 

 shipped. 



At other localities in the Crystalline area manganese is 

 found, in massive and nodular forms and as a black clayey 

 mixture of finely divided manganese oxide, in residual clays 

 derived from the decay of hornblende- and mica-schists. The 

 mica-schist is often garnetiferous. 



The above occurrences of manganese in the crystalline 

 rocks indicate (i) a concentration of the ore along and near the 

 contact between certain formations ; and (2) accumulation of 

 the ore in the residual clays derived from the decay of various 

 siliceous crystalline rocks. 



Mineralogical Forms of tJic Ores. — The silicate, oxide and 

 carbonate of manganese are found to some extent in the rocks 

 of the Crystalline area. Neither the silicate nor the carbonate is 

 of commercial importance. Manganese-bearing silicates are 

 widely distributed among the more common rock-forming min- 

 erals ot the area, and are of great importance in that they form 



