BULL. GEOL. SOC. AM 



VOL. 10, If 



PL. 38 



FifiURE 1. — PlIOTOJIICKOGRAl'll Of AVr.bTERI.i liRAY GrANITE 



The dark material is biotite and its relative abundance is illustrated. Actual diameter, 



4 millimeters 



Figure 2.— Photojiicrograj']! oy l]uj:.Ni]],EMjj;-.^xEiss found near Westeki.y 



The solid, dark material is hornblende. The narrow dark strips are biotite. Actual 

 diameter, 4 millimeters 



PHOTOMICROGRAPHS OF GRANITE AND GNEISS 



