2 12 Bulletin of Laboratories of Demson University. [Vo). xii 



employed in working the manganese are now used for mining 

 the ocher. Such occurrence is well illustrated on the property 

 of the Blue Ridge Ocher Company, where large quantities of 

 manganese-ores were formerly mined, and the tunnels and 

 shafts are now utilized for removing the ocher. On the same 

 property a large quantity of hard and porous spongy masses 

 of limonite, occurring as lenses and irregular seams in the ocher 

 beds, was being removed with the ocher during the summer 

 of 1902. 



At the Etowah river, on the Georgia Peruvian Ocher Com- 

 pany's property, several miles southeast of Cartersville, large 

 clusters and groups of barite crystals are formed in the pockets 

 of ocher and in the fractures and caverns of the quartzite. The 

 barite often occurs in divergent groups of massive tabular crys- 

 tals, giving crested appearance, grading into both straight and 

 curved laminated masses. 



Chemical Composition of the Ocher. 



The chemical composition of both the crude and the refined 

 ocher is shown in the table of analyses below, made by the N. 

 P. Pratt laboratory, in Atlanta, Georgia. 



Table of Chemical Analyses of the Crude and Refilled Ocher. 



Samples. 



I. 



II. 



III. 



IV. 



V. 



VI. 



VII. VIII. 



Fe^Os, 

 Al,03, 

 FeO, 

 MnOj, 

 SiO„ (free 



sand), 



SiOj (combined as sili- 

 cates), . . 

 HjO at 105° C, . 

 TIjO above 105° (.", . 



Total, 



Per 



Cent. 

 72.29 



5-55 

 0.46 

 0.87 

 6.65 



3-9^ 

 0.55 

 9.22 



Per 

 Cent. 

 56.29 

 10.15 

 0-39 

 0-54 

 S.94 



9.49 



2.08 



11-34 



Per 



Cent. 



65-49 

 7.20 



1.80 

 7.76 



6.85 



0.40 



10.50 



Per 



Cent. 



54.60 



6.68 



1.50 

 17.42 



10.08 

 0.48 

 9.24 



Per 

 Cent. 



67-37 

 6.85 



2.04 

 6.54 



6.61 

 0.96 

 9-63 



Per 



Cent. 



61.40 



7.14 



2.00 

 1 1.89 



5-84 

 0.46 



9-37 



Per 



Cent. 



67-32 

 5.86 



6.35 

 0.78 

 9.60 



Per 

 Cent. 



62 79 

 6.94 



9.14 6.20 



9-7S 

 0.50 



99-57 99-22 100.00 100.00 100.00 100.00 99.05 



