Adirondack Region — Magnetic Iron Ores. 7 



a large amount of Bessemer ore, and a few small mines, but which 

 are no longer worked. 



n -THE ADIRONDACK REGION, INCLUDING THE LAKE 

 CHAMPLAIN MINES -MAGNETIC IRON ORES. 



The Adirondack region, the great mountain plateau of Northern 

 New York, is bounded by the valleys of Lake Champlain on the 

 east, of the St. Lawrence river on the north and north-west, of Black 

 river on the west, and the Mohawk on the south. It occupies nearly 

 all of Warren, Hamilton and Essex counties, the western and 

 southern parts of Clinton, the southern parts of Franklin and 

 St. Lawrence, the eastern part of Jefferson and Lewis, the northern 

 towns of Oneida, Herkimer, Hamilton and Saratoga, and the north- 

 west corner of Washinoton counties. Its area has been estimated to 

 be at least 10,000 square miles. Dr. Emmons, in his Survey of the 

 Second Geological District, described the rock formations of this 

 territory as gneisses and hypersthene rock principally ; and the 

 former he regarded as the prevailing rock, excepting in a large 

 triangular area in Essex county, where the outcropping rocks are 

 hypersthene.* The gneissic rocks resemble closely the rocks of the 

 Highlands of the Hudson, and they have been recognized by 

 geologists generally as Lower Laurentian. 



The so-called "hypersthene rocks " of Dr. Emmons consist of 

 labradorite and pyroxene or labradorite with hypersthene and some 

 pyroxene, and hence are often designated as a Labrador series. In an 

 article on the "Laurentian Magnetic Iron Ore Deposits in Northern 

 New York," Charles E. Hall has grouped the magnetites in three 

 series, or horizons ; the lowest, the Laurentian magnetites ; second, 

 the Laurentian sulphurous ores ; and highest, the Labrador group, 

 with its titaniferous ores.f 



Magnetite is one of the common minerals in the Adirondacks, and 

 is widely distributed, both as a constituent or accessory mineral in 

 roc Us, and in beds of workable extent. Mines have been opened in 

 all parts of the region, but the greatest development has been in the 

 valley of Lake Champlain, and hence the ores are known in the 

 market as Lake Champlain ores. In it are the famous Port Henry 

 mines and others. The Chateaugay range cannot be said to lie in 



* Emmons : Survey of the Second Geological District, Albany, 1842, pp. 27-33 and 

 75-78. 



t Thirty-second Annual Report, N. Y. State Museum, pp. 133-140. 



