3l6 smithsonian miscellaneous collections [vol. 45 



Summary 



1. Four rocks are described, namely, hypersthene-akerite, una- 

 kite, epidosite, and altered olivine-basalt. The first two mentioned 

 are of more than ordinary interest, owing to their rather restricted 

 distribution. 



2. The term unakite has been applied to a rock whose mineral 

 components would place it among the granites, with epidote as an 

 essential constituent, but whose analysis is relatively basic for this 

 type of rock. This name was applied by Bradley in 1874 to a similar 

 rock from the Unaka mountains. North Carolina, and so far as the 

 writer is aware, its occurrence at other places has not been referred to. 



3. The name hypersthene-akerite has been applied to a hyper- 

 sthene-quartz-diallage-syenite in the sense originally proposed by 

 Brogger. 



4. The unakite has originated from the akerite by the process of 

 hydrometamorphism, aided and perhaps induced by dynamic dis- 

 turbances. 



5. The relative ages of the akerite and basalt are not given, since 

 they could not be determined with certainty in the limited time avail- 

 able for field work. It is hoped that in the near future opportunity 

 for more extended study will be presented. The basalt is younger 

 than the granite on the eastern slope. 



