Art. IX.] Watson, Mangatiese Ore-Deposits of Georgia. 161 



of specimens collected by Mr. A. H. Brooks of the U. S. Geo- 

 logical Survey, i mile east of Rowland, Bartow county, Geor- 

 gia : 



Analysis of Granite, Cartersville District. 



SiO„ 



Fe,0, - - 



FeO, 



MgO, ... 



CaO, 



Na,0, 



KjO, 



HP+, - - . 



HjO— , ... 



Total, - - - 99.77 



Brooks has given the following petrographic data on the 

 granite from this locality : 



"Contains microline, some plagioclase, abundant pyroxene, partly altered 

 into chiefly uralite and chlorite, some biotite with frequent inclusions of rutile, 

 much blue vitreous quartz, apatite, zircon and magnetite."* 



In places, the border-portion of the granite mass is over- 

 lapped by a coarse feldspathic conglomerate whose mineral con- 

 stituents were evidently derived from the granite, since tlie mi- 

 crocline and the blue quartz of the granite enter largely into the 

 composition of the conglomerate. In other places a series of 

 black graphitic slates are in contact with the granite. No fos- 

 sils are known to occur in the conglomerates and slates, and on 

 account of their appearance of extreme age, Hayes^ has grouped 

 them as Algonkian (Ocoee). 



To the south of the Corbin granite-area, the conglomerates 

 and slates increase in metamorphism and apparently pass into 

 schists and gneisses, whose origin, whether igneous or sedi- 

 mentary, is unknown. 



The extreme southeast corner of the map (Fig, 3) com- 

 prises narrow belts of granite, gneiss and hornblende (amphibo- 



» Clarke, F. W., Bulletin, U. S. Geol. Survey, No. 1 68, 1900, p. 55. 

 * Hayes, C. W , Trans., xxx., 408 (1901). 



