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[Assembly 
magnetic ores are the most common, and it appears too, that this species 
is characteristic of this formation. And again, in the western part of 
Essex, and eastern part of St. Lawrence, the rock contains another va- 
riety of magnetic iron, differing in some respects at least, from the com- 
mon magnetic iron along the lake; and to mention another formation of 
iron, we have the brown hematites, situated among the limestones of 
Vermont, Massachusetts and Connecticut, and occupying the valleys of 
the green mountain range. Each geological formation furnishing an 
ore specifically different. 
From these facts, and others which might be produced, it appears 
that ores of iron have been developed in all the great geological forma- 
tions in this country, and in each it possesses some distinguishing pecu- 
liarities, so that when the same species is produced in two different for- 
mations, the circumstances under which they have been deposited have 
effected such changes in them that the process for reduction requires a 
meterial alteration. It is not intended, however, to assert that the 
characters of a species are so far changed that it can not be recognized 
as the same species, but that it has suffered a remarkable modification; 
and such is the fact in the magnetic ores, a part of which belong to the 
gneiss along the Champlain, and a part to the granitic or hypersthene 
rock of the highlands of Essex. 
Bog Ore, 
I visited a number of the deposits of this ore in the county, and found 
them all to have been produced from the decomposition of pyritous iron, 
and the oxides intermixed with it. This is the case certainly with some 
of the larger collections, as their formation could be traced directly to 
the parent rock, in which the sulphuret is largely disseminated, and 
which is also undergoing constant decomposition. Some small collec- 
tions are found at the margins of springs, the waters of which are charg- 
ed with the oxide and carbonates of iron, which on exposure to air at 
the surface, lose their carbonic acid, and form precipitates of the ore.— 
Deposits of this kind, may be seen at De Kalb village. 
One of the largest collections of the former character, is in Hermon, 
on the lands of Dr. Thatcher, and Mr. Kent. The extent of those beds 
is not exactly known, but the quantity is inexhaustible. 
One fault which all the ores derived from this source have, is, the inter- 
mixture of sulphuretof iron, which renders it necessary to expel the sul- 
phur, by roasting, previous to subjecting them to the action of the fur- 
nace. Probably, however, exposure to the air a few months, in most 
