jYutive Copper of Lake Superior, ^-e. 211 



through a stratum of red sand-stone, and covered by a very 

 heavy deposit of alkivial soil full of water worn fragments 

 of stones and pebbles, and imbedding occasional masses of 

 native copper. Such is the character of the country in the 

 immediate vicinity of the copper rock, and the latter is man- 

 ifestly one of those imbedded substances, which has been 

 fortuitously exposed to the powerful action of the river 

 against an alluvial bank. 



During our continuance upon this stream we found, or- 

 rather procured from the Indians, another mass of native 

 copper weighing nine pounds (Troy) nearly ; which will be 

 forwarded to the War Department. This specimen is par- 

 tially enveloped by a crust of green carbonat of copper,, 

 which is in some places^5roMs, and on the under side mix- 

 ed with a small portion of adhering sand, and some angular 

 fragments of quartz, upon which it appears to have fallen 

 in a liquid state. There is also an appearance of crystal- 

 ization upon one side of it, and a portion of adhering black 

 oxyd, the nature of which it is difficult to determine by 

 ocular inspection. Several smaller pieces, generally weigh- 

 ing less than a pound, were also procured during our ex- 

 cursion up the Ontonagon, and in the regions east of it, but 

 all, excepting those cut from the large mass, are somewhat 

 oxydated, or otherwise encrusted upon the surface. The 

 geological structure of the country in detail, and the mine- 

 ral appearances of the shore about the copper rock and 

 at other points along the river, between that and the lake, 

 are also of a highly interesting character, but do not appear 

 to me to demand a more particular consideration in this re- 

 port. 



The discovery of masses of native copper is generally 

 considered indicative of the existence of mines in the 

 neighborhood. The practised miner looks upon them as 

 signs which point to larger bodies of the same metal in the 

 earth, and is often determined, by discoveries of this nature, 

 in the choice of the spot for commencing his labours. The 

 predictions drawn from such evidence, are also more san- 

 guine in proportion to the extent of the discovery. It 

 is not, however, an unerring indication, and appears liable 

 to many exceptions. A detached mass of copper is some- 

 times found at a great distance from any body of the met- 

 al, or its ores ; and these on the contrary, often occur in the 



