238 



CERTAIN SAND MOUNDS OF 



one-half native silver in mechanical combination has been reported. During all 

 our investigations we have been unable to learn of native copper from any other 

 locality on this continent, which is visibly argentiferous, and as the researches of 

 others have had a like result, we are strongly of the opinion that implements or 

 sheets of copper from the mounds, in which silver can be seen, may be considered 

 as surely having derived their material from Lake Superior. 



We are informed by Professor Cushing that an object of copper containing 

 visible silver was found in northern Florida. 



Mining was unsuccessfully attempted by the English at Lake Superior in 

 1771-1772, and it was not until 1844, after the admission of Michigan to statehood, 

 that a steady output was furnished from the district. 1 



From this it is evident that no "Lake" copper can have been furnished by 

 Europeans during any possible mound building period. 



So many evidences of prehistoric intercourse with regions to the south have 

 been found in the mounds of our Western States that it is safe to assume that the 

 Lake Superior district furnished the greater part of the copper in use by Southern 

 Indians, which was doubtless traded for shell implements and ornaments, or for the 

 raw material obtainable only on the seaboard or on the Gulf coast. Moreover, as 

 aboriginal copper with visible admixture of silver has been found in the Southern 

 States, it is virtually safe to assume that with such metal went other " Lake" cop- 

 per in which silver is not perceptible. 



Dr. Harry F. Keller, whose residence in Michigan as Professor of Chemistry 

 in the Michigan Mining School at Houghton, gave him exceptional advantages in 

 respect to analysis of "Lake" copper, has furnished us with the following unpub- 

 lished analyses made by himself: — 



" Native copper from the Tamarack mine, 2 Lake Superior. 



Copper 



. 99-8049 



per cent. 



Silver 



. 0-0151 



u 



Iron 



. 0-0240 



a 



Silica 



. 0-0193 



a 





99-8633 



a 



uopper from Kearsarge mine 



, Lake Superior. 





Copper 



. 99-7627 



per cent. 



Silver 



. 0-0183 



a 



Iron 



. 0-0223 



a 



Arsenic 



Trace. 





Silica 



0-0210 



per cent 



99-8243 



" Sp. gr. 8-912." 



1 Copper Resources of the United States," by James Douglas, New York. Author's edition, 1891. 



2 The vein in the Tamarack mine is conglomerate. Dr. Keller informs us, however, that the analysis 

 was made from a good sized nugget. Such specimens are occasionally found in conglomerate mines. 



