114 C. P. Williams and J. F. Blandy, 



Thus the Isle Eojale lode yields in the following proportion: 

 of mass and barrel (heavy) copper 60 per cent, stamp (tine) cop- 

 per 40 per cent, whilst the great metalliferous deposit of tbe 

 second series produces of mass and barrel copper 43 per cent, and 

 of stamp copper 56 per cent. This comparison has been found 

 to hold good through a series of years. All the intercalations of 

 conglomerate opened in this zone, from its western to its eastern 

 boundary, are cupriferous, and most of them have overlying 

 them contact deposits of good width in which this metal has been 

 concentrated, while not one bed of the sedimentary rocks found 

 west of the conglomerate forming the western boundary of the 



Near the eastern limit of this zone several of the lodes have 

 been found to contain a small amount of the sulphuretted ores, 

 and a large amount of quartzose vein matter with arsenids of 

 copper (whitneyite and domeykite) has been found in angular 

 fragments on the surface in the same vicinity, pointing to the 

 proximity of veins of an age and composition different to any- 

 thing yet opened in the Portage Lake District, and most proba- 

 ble synchronous in formation and repletion with the veins mined 

 in the Southern or Bohemian range of Point Keweenaw, 



Fewabic Zone. — Besting on the rocks of the first named series. 

 but separated from them by a copper-bearing conglomerate ^vl^l 

 its accompanying contact vein, and occupying a width of r.e;!";} 

 1300 feet, occurs the Pewabic zone. In this formation ten ucji 

 of metal-bearing amygdaloid have been opened, of which three 

 only have been worked to any extent, and one of these, that 

 from which the series has been named, has given wonderful re- 

 sults, having yielded about 600 lbs. of ingot copper to the cubic 

 fathom. The rocks are characterized by the almost total absence 

 of epidote, whilst those beds carrying copper have a large amoi!^^- 

 of calcareous spar and laumontite entering into their conii'C.-Ki'_^-' 

 No conglomerate intercalations occur in the space occupiov.! t-;- 

 these rocks, though it is limited on the west by a belt of ;;i:c-' 

 rock of 40 feet thickness, which, though opened at several j^"-''''- 

 J of copper. The character of the copper pr-" 



dts mined in this series has be^;^ 



of the rocks of the Isle Uo;-^" 

 zone. No traces of any sulphuretted or other ores of d^; . * 

 have been found in this series. 



Hancock Zo7ie.—The rocks comprised within this zoi:- 

 width of nearly 600 feet, being included betw-een tin- " 

 conglomerate of tlie Pewabic zone, upon which they v - 

 anc'i— ^- T -^ *^- — - rock of a wadth of about 45 fee:. 

 TO..',:, f nearly 45°, and are of a much -"^oit-r 



or. J noticed to the east of them, chlorite 



en: composition, and the entire formation 



