156 



ECONOMIC GEOLOGY 



copper fields or districts. The Prince of Wales Island; Prince 

 William Sound; Copper River district, and the Kotsina district. 

 (See Fig. 95.) 



(1) On Prince of Wales Island, contact metamorphic ores 

 occur in irregular masses along the contacts of the intrusives with 

 limestones. The copper mineral is chalcopyrite. It is associ- 



FIG. 95. Geologic map of Copper Mountain Region, Prince of Wales 

 Island, Alaska. After Wright. (By permission of the Macmillan Company, 

 from Ries' Economic Geology.) 



ated with pyrrhotite, pyrite and magnetite with a gangue of am- 

 phibole and feldspar. Fissure veins and disseminated ores are 

 also encountered. (See Fig. 96.) 



(2) On Prince William Sound the ore is chalcopyrite dissemi- 

 nated through the metamorphic schists. The ore is associated 

 with pyrite and pyrrhotite in cavity fillings. Also as replace- 



