208 WATSON AND CLINE ROCKS OF THE BLUE RIDGE REGION 



Norms of Akerites corresponding to Analyses of Rocks on page 207 



Q . 



Or 

 Ab 

 An 



. 

 Ne 



01 . 

 Di . 

 Hy 

 II . 

 Mt 

 Hm 



I 





II 





Ill 



IV 



Y 



VI 



VII 



15.2 





11.5 





12.6 



26.5 



2.8 



.7 





32.2 





33.4 





30.0 



19.5 



26.1 



18.3 



30.6 



34.1 





44.5 





37.2 



23.1 



41.4 



45.6 



43.0 



7.0 





2.8 





9.7 



12.0 



13.1 



19.2 



7.S 







1.6 







7.0 

























.3 



















2.7 



3.4 









3.0 





4.5 



5.0 



8.2 



5.0 





2.7 

 1.4 





2.8 



.9 



3.5 



3.7 

 2.3 

 3.7 



4.4 

 2.3 



4.2 



7.9 

 1.8 





1.3 



1.7 



1.6 



4.9 













.5 









Summary of Classification 









Number. 





Symbo: 



1. 



Magmatic name. 







I 



I, 



, 4. 2. 



3. 





toscanose 









II 



I. 



5. 1. 



3. 





phlegrose 









III 



I. 



5. 2. 



3. 





pulaskose 









IV 



I. 



4. 2. 



3. 





toscanose 









V 



II 



, 5. 2. 



4. 





akerose 







- 



VI 



11. 



5. 2. 



4. 





akerose 









VII 



II. 



5. 2. 



3. 





monzonose 









Bocks belonging to the akerite type in Massachusetts are found chiefly 

 in the eastern part of Essex County associated with granites and nepheline 

 syenites. They have been described by Wadsworth, 19 Sears, 20 and Wash- 

 ington, 21 who agree in classing them with the quartz-bearing angite 

 syenites. Washington compares his analysis of the akerite from Glou- 

 cester, Massachusetts (I of table of analyses, page 207), with one of akerite 

 (porphyritic), described by Brogger, 22 occurring between Thinghoud and 

 Fjelebua, Norway (II of table of analyses, page 207). He remarks that 

 the Massachusetts rock shows close parallelism with the more acid of 

 Brogger's akerites and belongs to an extreme type, since the akerites as a 

 group are more basic. Although the analysis of the Massachusetts rock 

 shows rather high lime, Washington states that this is all used up in the 

 formation of pyroxene, leaving none for lime-soda feldspar, which the 

 microscope shows is not present. This rock is an alkalic and sodic tos- 

 canose whose plagioclase is albite. 



18 H. S. Washington : Professional Paper No. 14, U. S. Geol. Survey, 1904. 

 18 M. E. Wadsworth : Geol. Mag., 1885, p. 207. 



20 J. H. Sears : Bull. Essex Inst, vol. xxiv, 1892, and vol. xxv, 1893. 



21 H. S. Washington : Jour. Geol., vol. vi, 1898, pp. 787-808 ; see especially pp. 796-799. 



22 W. C. Brogger : Zeitsch. f. Kryst, vol. xvi, 1890, p. 55. 



