26 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 60 



grinding of thin sections of these small pebbles, which averaged 

 about 3 millimeters in diameter, was difficult, but about a half dozen 

 of them were successfully prepared. These sections were all alike 



26 



27 ^-^^-^ 28 



Figs. 24-28. — 24-25, Olivine ; 26, titanite ; 27, ilmenite ; 28, allanite. 



and consisted of a fresh rock of marked ophitic texture having laths 

 of twinned plagioclase feldspar in a ground of glassy augite. The 

 sections also contained scattered comparatively large tabular crystals 

 of ilmenite. 



