280 



the Quincy Mine, P. L., running with the formation, while at 

 Keweenaw Point, until this year, the veins were supposed invari- 

 ably to cross the formation at nearly right angles. 



Mr. Dupee requested Dr. C. T. Jackson to express his views 

 with regard to this mineral deposit on Eagle River. 



Dr. Jackson then stated, that when he first called public 

 attention to the native copper mines on Lake Superior, in 1844, 

 he made a full survey of the whole mining districts on Eagle 

 River, and at Copper Falls, and had published in his reports to 

 the Lake Superior and Copper Falls Mining Companies, very 

 full descriptions of their respective mining " countries," and of 

 the copper and silver veins included in the rocks. On reference 

 to his first Report, in 1844, it will be found that this scoriaceous 

 or " ash bed," as seen on the margin of Eagle River, is described 

 as exhibiting one wall, while for the distance of ninety feet, at 

 right angles to it, the rock is impregnated with particles of native 

 copper and silver, which are most abundant in the "ash bed," 

 there called the "rotten rock." The other wall of this bed was 

 not then found, and he was glad to learn that it had now been 

 discovered by the miners. Regular veins had also been found 

 in this same scoriaceous trap-rock ; and at the time the Lake 

 Superior Company stopped work, through bad counsels, there 

 was a vein with well-defined walls, and rich in copper and silver, 

 at the bottom of their tunnel under the river. Copper mining, 

 at that day, was so little understood by the early adventurers, 

 and so many difficulties stood in their way, in an unbroken 

 wilderness, that the first mining company abandoned their mines 

 before they had fairly commenced regular works. The Phoenix 

 Company, having purchased the property, are now mining with 

 greater advantages, and it is believed with fair prospects of 

 ultimate success. The ash bed, mentioned by Mr. Dupee, is a 

 comparatively soft scoria, or rotten amygdaloid, formed by the 

 mixture of molten trap-rock and fine sandstone, which have 

 been, as it were, melted together into a very spongy kind of 

 scoria, the aqueous vapor having rendered it remarkably vesicu- 

 lar. The amygdaloidal and scoriaceous beds of trap-rock, occur 

 in alternate layers with coarse conglomerate and fine red sand- 

 stone strata, appearing as if immense sheets of the molten trap 



