"Say 
BOR. Emerson— Dyke of FE leeolite-syenite in New Jersey. 303 
crumbled into loose pieces and into a fine sand, which form a 
range of low hills with gentle slopes, and which, seen from a 
distance, look exactly like hills of sand or drift. 
- “The dyke here consists of a rather coarsely granular aggre- 
gate of labradorite, sphene, mica, quartz, pyroxene and iron 
pytites. ‘The sphene is of a brown to yellowish brown color, 
of an adamantine luster, and occurs in small, more or less per- 
fect, crystals, in such gveniy as to form one of the principal 
ck. 
€ iron pyrites is profusely disseminated throughout the 
rock, and causes the rapid decomposition. 
which skirts the mountain on the east, at the house of Mr. D. 
B. Roloson, this is seen in great perfection on the hillside, and 
in the orchard above this gentleman’s house, a band of lime- 
stone oceurs—a dark gray fine grained rock, which might be 
easily mistaken for a fine-grained diorite. It has, however, the 
rusty corroded surface of a siliceous limestone. Scales of bio- 
tite are disseminated in it in considerable abundance, and the 
rock is so rich in magnetite that the coarse powder is readily 
