78 



ECONOMIC GEOLOGY 



FIG. 57. Map showing mineral deposits of Alaska. After Brooks. 

 (By permission of the Macmillan Company, from Ries' Economic Geology.) 



Gabbro A/bite Diorite State 



traversed by veins of 

 Ca/cite & .Quart* 



FIG. 58. Gold ore in transverse veins in the Ready Bullion mine, Tread- 

 well, Alaska. (After A. C. Spencer, U. S. Geological Survey.) 



