l.V, 



bodies are centered in the localities which have undergone the 

 extrusive intrusion and Assuring. 



The copper ore occurs in flat lenses in t he metamorphosed lime- 

 In the Highland Boy mine there are large lenticular 

 1 UK lies of chalcopyrite in the 

 fissured marble adjacent to 

 the intrusives. The ore oc- 

 curs disseminated through the 

 igneous rocks, and limestone. 



According to J. M. Bout- 

 well, heated, aqueous, min- 

 eral-bearing solutions, rich in 

 carbon dioxide and potassium 

 oxide, rose along strong north- 

 east and southeast fracture 

 zones, altered their walls by 

 adding quartz to quartzite, 

 impregnating marble with 

 metallic sulphides and specu- 

 lar iron ore, and silicifying, 

 seriticizing, and impregnating 

 monzonite with metallic sul- 

 phides and depositing lode 

 ores in largest volume between 

 calcareous and carbonaceous 

 walls, mainly by filling, and 

 partially by replacement. 

 The same author furthermore 

 states that "it is probable 

 that the principal scource of 

 the copper ore in the lime- 

 stone was the magma of the 

 intrusive, that the mineral 

 elements were transported by 

 the intrusives and by the 

 thermal solutions and vapors 

 emitted from both their super- 

 ficial and deeper portions and that the ore was deposited by 

 molecular replacement of a metamorphosed, at least partially 

 in.ii inorized and silicified, country rock" (Figs. 93 and 94). 



(5) The Alaskan District. In Alaska there are four distinct 



