THE MONTEREGIAN HILLS 269 



form and the position of the rock in the Quantitative classifica- 

 tion determined. It is found to be as follows : 



Class II, dosalane. 



Order 5, germanare. 



Rang 3, monzonase. 



Subrang 4, akerose (grad = polmitic). 



It thus, in composition, occupies, in a manner, a middle place 

 between the essexose and andose of Mount Johnson. 



The Pulaskite. — This soda-syenite which, as above men- 

 tioned, forms the outer zone of the mountain, girdling the essex- 

 ite, is less abundant than the latter and differs greatly from it in 

 appearance. This difference is due chiefly to the fact that it 

 is much lighter in color, being pale-yellow or buff instead of 

 dark-gray, the lighter color being due to the very small propor- 

 tion of iron-magnesia constituents present and the marked pre- 

 ponderance of the feldspars. The rock also has a more massive 

 structure, the fluidal arrangement of the constituents often met 

 with in the essexite being absent, and it weathers in a somewhat 

 different manner. It possesses, moreover, a species of por- 

 phyritic structure, owing to the development of the feldspar in 

 two forms: first, as stout prisms, up to lo™'" in diameter, which 

 are light-gray in color and very abundant ; and, secondly, in the 

 form of smaller laths of a yellow or buff color which, in associa- 

 tion with the iron-magnesia and other constituents, form a sort 

 of groundmass in the rock. 



The constituent minerals of the rock are biotite, hornblende, 

 (pyroxene), soda-orthoclase, nepheline, sodalite, apatite, mag- 

 netite, and sphene. The darker constituents are identical in 

 character with those occurring in the essexite, and therefore do 

 not require to be described again. Not only are they as a class 

 much less abundant in this pulaskite, but the mica here prepon- 

 derates, being the prevailing iron-magnesia constituent, while 

 the hornblende is much less abundant and the pyroxene is 

 entirely absent. It may be noted, however, that the hornblende 

 sometimes possesses the greenish tint referred to as occasionally 

 seen about the borders of the hornblende individuals in the 

 essexite, indicating probably that, the pulaskite magma being 



