I >/./'/ /. Ml I 1/,N 



113 



chamber deposits and as gash veins; also it occurs in what is 

 known as flats and pitches. (See Fig. 71.) 



The most important lead deposits of the United States are of 



: .''.'..; !;'// : ; ':'.*v ; /: ' : " ; .\v'-. : : {: / * T - w 



1- .- UPPER GALENA 



MIPPLE GALENA 



LOWER QAL.EHA 

 BLUE LIMESTONE. 

 LIMESTONE 

 PETER'S 3ANPSTQNE 



FIG. 72. Ideal section in the lead and zinc region of Wisconsin, showing 

 the forms of ore deposits at the different horizons. (After Chamberlain.) 



Grtywacke Dioritt Calcitc Quart* Galena Blendi 



FIG. 73. Section of the Adelbert lodes, Pribam, Bohemia. (After J. 



Zadrizil.) 



metasomatic origin. They occur in the limestones of all ages 

 (Fig. 72). Fossils have been replaced by galenite retaining both 

 the external form and internal structure of the organism. Such 



