GEOLOGICAL AND MINERALOGICAL NOTES. 125 



Cape Ann region, printed in connection with the report, 

 these areas were recorded as hornblende-granitite. In the 

 whole area of the augite-syenite rock there are several 

 dome shaped and irregular masses of the hornblende- 

 granitite and, as the two forms of rock are distinctly gran- 

 itic in type, it is not surprising that they have long been 

 considered as one formation. Indeed, on the surface of 

 some of the eroded augite-syenite outcrops, secondary 

 quartz has been developed to such an extent that it would 

 be impossible from a macroscopical examination to dis- 

 tinguish them from the hornblende-granite rocks, while a 

 few inches deeper, in the fresh unaltered mass, the ab- 

 sence of quartz would at once show that the formation be- 

 longed to the syenite rock group. 



Paper read before the Essex Institute, Mar. 20, 1893. 



