JVative Copper of Lake Superior, SfC. 205 



cious metals, or to the action of the river, which during its 

 semi-annual floods carries down large quantities of sand 

 and other alluvial matter that may serve to abrade its sur- 

 face, and keep it bright. The shape of the rock is very- 

 irregular — its greatest length is three feet eight inches — its 

 greatest breadth three feet four inches, and it may altogether 

 contain eleven cubic feet. In size, it considerably exceeds 

 the great mass of native iron found some years ago upon 

 the banks of Red River in Louisiana, and now deposited 

 among the collections of the New- York Historical Socie- 

 ty, (1) but on account of the admixture of rocky matter, is 

 inferior in weight. Henry, who visited it in 1766 estima- 

 ted its weight at five tons. (2) But after examining it with 

 scrupulous attention, I have computed the weight of metal- 

 lic copper in the rock at twenty two hundred pounds. The 

 quantity may, however, have been much diminished since 

 its first discovery, and the marks of chissels and axes upon 

 it with the broken tools lying around, prove that portions 

 have been cut off, and carried away. The author just quo- 

 ted observes " that such was its pure and malleable state, 

 that with an axe he was able to cut off a portion weighing 

 a hundred pounds." Notwithstanding this reduction it may 

 still be considered one of the largest and most remarkable 

 bodies of native copper upon the globe, and is, so far as 

 my reading extends, exceeded only by a specimen found in 

 a valley in Brazil weighing 2666 Portuguese pounds. (3) 

 Viewed only as a subject for scientific speculation, it pre- 

 sents the most interesting considerations, and must be re- 

 garded by the geologist as affording illustrative proofs of an 

 important character. Its connexion with a rock which is 

 foreign to the immediate section of country where it lies, 

 indicates a removal from its original bed, while the intimate 

 connexion of the metal and matrix, and the complete en-^ 

 Telopement of individual masses of the copper by the rock, 

 point to a common and contemporaneous origin, whether 

 that be referable to the agency of caloric or water. This 

 conclusion admits of an obvious and important application 



(1) See Brace's Mineralogical Journal, p. 124, 218. 



(2) See Henry's Travels and adventures, p. 205. 



(3) Philips' Mineralogy. 



