Native Copper of Lake Superior, &. 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 
inregular—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 
the banks of Red River in Louisiana, and now depos 
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 wi 
scrupulous attention, I have compu weight of metal- 
lic copper in the rock at twenty two hundred pounds. The 
quantity may, however, have been much dintinished. sees 
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 
avalley in Brazil weighing 2666 Portuguese pounds. (3) 
Viewed only as a subject for scientific akan, 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, 
rss a removai from its original bed, while the intimate 
connexion of the metal and matrix, eid the complete en- 
velbpement of individual masses of the copper by the rock, 
point to a common and i iid ae origin, whether 
that be referable to the agency of caloric or water. This 
conclusion admits of an obvious and important application 
(1) See Bruce’s Mineralogical Journal, p. 124, 218. 
(2) See Henry’s Travels and adventures, p. 205. 
(3) Philips’ Mineralogy. 
