IRON ROCK. 
95 
of Essex and Orange counties, New York, it is in veins. The 
magnetic iron district of New York begins just north of the 
valley of the Mohawk, and occurs in all the counties in that 
part of the state, the veins themselves occurring in subordinate 
or smaller districts; or, in other words, veins of this ore appear 
to cluster together in certain areas, as it is rare that a single 
vein is found occupying a district: where one vein is found, it 
is usual to find several running in parallel lines. The specular 
ore occupies two or more districts in Jefferson and St. Law¬ 
rence counties. These are usually associated with serpentine 
or pyrocrystalline limestone. Magnetic and specular iron ores 
are composed of 
Magnetic oxide. Specular oxide. 
Oxygen, 28‘21 30'66 
Metallic iron, 71'79 69'34 
Both species are variable in composition from foreign mat¬ 
ter, particularly quartz. The special relations of the two spe¬ 
cies of iron ore will be given in the part relating to mining. 
I have given the direction of the ranges or belts of the pyro¬ 
crystalline limestone and serpentine; and it is discovered that 
these two rocks skirt the eastern base of the Appalachians 
through their entire length from northeast to southwest. The 
same fact may be stated respecting the range of the octahedral 
iron in Orange county, adjacent to the Highlands. Among 
this cluster of mines I may enumerate some seven or eight 
extensive formations, among which are the Long, Rich, Forchee, 
and Wilkes mines. The formation which carries the magnetic 
iron passes into and through the state of New Jersey from the 
Sterling mines to those of Pompton, of which there are some three 
or four veins which are included in a gneiss abounding in horn¬ 
blende—a rock which is quite massive, and is sometimes called, 
from its resemblance to granite, a gneissoid granite. A cluster 
of many veins are known, and have been worked, in the neigh¬ 
borhood of Dover. This seems to be a distinct belt, and pursues 
a southwesterly course towards the Delaware. A parallel 
belt more westerly is also known, and which embraces the zinc- 
