THE ST. JOHN'S RIVER, FLORIDA. 



237 



obtained ; it exhibited a pure copper-red color, metallic lustre, and gave a specific 

 gravity of 8-896. 



" All the elements likely to occur in the metal were carefully tested for : gold, 

 lead, bismuth, arsenic, tin, tellurium, selenium, cobalt, and nickel were found to be 

 absent ; the analysis yielded : — 



I. 

 " Copper 

 Silver 



Antimony 0-0020 



Iron . 0-0491 



0-1220 

 Trace. 

 0-0144 



Oxygen . 

 Sulphur . 

 Gangue (silica) 



99-7587 per cent. 

 0-0039 .« 



II. 



99-7620 per cent. 



0-0037 

 Not determined. 



0-0503 per cent. 



0-1094 



0-0110 



99-9501 



" The oxygen is present partly as oxide of iron, and partly as cuprous oxide. 

 If we deduct these admixtures, as well as the silica, it is seen that the metal itself 

 contains 99 "994 per cent, of pure copper." 



The reader must bear in mind that the oxygen referred to was not present 

 throughout the entire mass of copper as combined oxygen, which does not occur in 

 native copper, but locally, as explained above. We think it well to make this ex- 

 planation, as possibly all our readers are not fully informed as to the difference, and 

 a misconception might arise. 



James Colquhoun, Esq., has kindly forwarded to us samples of native copper 

 from the Fry mine, Clifton, Arizona. This copper, submitted to Ledoux and Com- 

 pany, yielded the following results 



" Copper 

 Silver 

 Iron 

 Lead 



99-210 per cent. 

 0-003 

 0-045 



None. 



" Note : The sample was examined for bismuth, arsenic, antimony, nickel, 

 cobalt, none of which was present. 



" The sample also contains some silicious matter not combined with the cop- 

 per, but held mechanically in the interstices. As this could not be considered an 

 impurity in the metal, the amount was not determined." 



As this silicious matter was included in the preliminary weighing, its absence 

 from the result accounts for the apparently low percentage of copper in the speci- 

 men. 



The Lake Superior District. — As we have stated, the copper of the Lake 

 Superior district, where abundant evidence of prehistoric mining exists, is native, and 

 argentiferous to the extent of about six ounces to the ton. When this percentage is 

 exceeded, the silver is visibly present in flakes, seams and streaks, from which at 

 times quantities of native silver can be cut. In fact, "Lake" copper with almost 



