1846.] Copper Mines. 65 



At Copper Harbor a vein of the black oxide of copper has 

 been discovered in the conglomerate about 14 inches wide, and 

 has been traced fifty feet. At Hayes' Point, the chrysocolla a 

 gfeen hydrous silicate of copper has been known for a long time. 



It is stated by Dr. Jackson that one of the most valuable loca- 

 tions of Lake Superior Mining Company is situated on the west 

 side of Eagle river, eight miles from Eagle harbor, and about a 

 mile and a half from the lake shore. The ore, which consists of 

 native copper and silver, is disseminated in the trap rock, so 

 thickly as to yield between ten and thirty per cent of its weight. 

 What is interesting, is the association of the copper and silver; 

 first in an alloy, and then again the silver forms a plate adherent 

 to the copper, without being at all alloyed with it. The cop- 

 per contains three-tenths per cent of silver. The vein has no 

 regular walls, but its workable extent is about eleven feet. It 

 has been traced half a mile. The yield of silver to the ton of 

 this ore is equal, according to Jackson's analysis, to 25/^ lbs. per 

 ton of silver; the copper to 1257 lbs. per ton. The above yield 

 was obtained from the coarsely sifted pieces; to this must be 

 added for the fine washings and siftings, a yield of 3,^ lbs. of sil- 

 ver, and of copper 250 pounds per ton. According to this 

 analysis, the value of silver in a ton of ore equals $568, and 

 the copper $241.12; value of the metal $701.12 per ton of ore. 

 It is proper to add that the reports from Lake Superior this win- 



per centum of fine copper, average produce in one hundred parts of ore. 

 Depth of the principal shafts — Woolf's engine shaft, 248 fathoms; Pearce's 

 engine shaft, 275 fathoms. Quantity of water raised, from 2000 to SOOK gal- 

 lons per minute. Power employed in drainage, 9 steam engines. Average 

 annual expense of drainage, £12,700 ($63,500). Quantity of ore annually 

 produced, 16,400 tons of copper ore, and a few tons of tin ore. Produce in 

 metal, 1517 tons of fine copper, and a little tin. Total returns or value of the 

 produce in metal, £119,900 ($5S9,000). Total cost of the mines, £98,500 

 ($492,500). Clear profit to the proprietors, £21,000 ($105,000) per annum. 

 Amount of capital invested, £75,000 ($375,000). Interest on capital invest- 

 ed 280 per centum, after paying back the original capital. Number of men 

 employed, about 2500 persons, of whom 1450 are employed under ground. 

 Manner in which the ores are disposed of, sold to the smelting companies, 

 and smelted by them at Swansea, in South Wales." 



