EXPLANATION OF PLATE 11. 



Figure i. — Cross section of vein traversing the rock. The rock is a fine 

 granular, aggregate of albite, with large blades of blue amphi- 

 bole c, scattered grains of sphene s, and occasional crystals of 

 zircon The vein is a coarse granular aggregate of albite f, 

 traversed by crystals of actinolite a, which for the most part are 

 secondary enlargments of the blue amphibole and in crystal- 

 lographic continuity with it. x 10. 



Figure 2. — Showing parallel growth of a group of crystals of blue amphibole. 



x 30. 



Figure 3. — Showing zonal composition of blue amphibole with predominance 

 of the actinolite molecule at the center, x 30. 



Figures 4 and 5. — Transverse sections of prisms of blue amphibole showing 

 color of the C ray. x 30. 



Figure 6. — Section parallel to c^Pco , showing color of J) ray. > 15. 



Figure 7. — Section parallel to ooPco , showing color of q ra y- : 5- 



Figure S. — Section parallel to coPco , showing color of a ray- x 3°- 



Figure 9. — Section parallel to 00 Poo", showing color ot [ ray. ■ 30. 



Figures 6-9 also show, on a larger scale than Figure 1, the secondary en- 

 largements of actinolite upon the broken ends of the blue 

 amphibole. 



Note. — No attempt is made to indicate the pleochroism of the actinolite, which is compara- 

 tively feeble. 



