Fig. I. — Diagram showing the range in feldspar composition for the various 

 materials studied. The numbers refer to those on the accompanying tables where 

 additional data are given. The solid black hnes opposite the material indicated in the 

 left-hand column show the range in feldspar composition for that material. Note the 

 wide range of feldspars in the material of sedimentary origin as compared to that 

 which is igneous in origin. 



