PLATE XLIII. 



Fig. a. - 



(Sp. No. 26070. AVithout analyzer, X 17.) 



Normal granular hornblende-gabbro. This Illustrates the normal medium-grained hornblende- 

 gabbro whicli occurs in this district. Xhe mineral constituents hornblende, feldspar, and iron oxide 

 can be readily distinguished. (Described, p. 248.) 



Fig. B. 



(Sp. No. 26069. With analyzer, x 18.) 



Schistose hornblende-gabbro. This illustrates a crushed specimen of a normal hornblende- 

 gabbro such as is represented above in fig. A, In tliis the feldspar has been partly granulated, and new 

 feldspar and quartz has resulted therefrom. The hornblende has also to a considerable extent been 

 recrystallized as light-green secondary hornblende. The mica has become chloritized. These are the 

 important secondary products. A very fair schistose structure has resulted from the crushing. 

 Carried to its full extent, metamorphism of this rock would result in producing an amphibolite or a 

 hornblende-gneiss. (Described, p. 248.) 



316 



