IRON ORES OF NEW YORK 533 



Saratoga, and the northwest corner of Washington counties. Its 

 area has been estimated to be at least 10,000 square miles. Dr. 

 Emmons, in his survey of the Second Geological District, decribed 

 the rock formation 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 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 Lau 

 rentian 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 rocks, and in beds of workable extent. Mines have 

 been opened in all parts of the region, but the greatest develop- 

 ment 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 

 can cot be said to lie in the Champlain valley. Therefore the 

 grouping by geological rather than by geographical lines alone, 

 is more definite, and the larger district of the Adirondacks is 

 better than any subdivisions according to our present knowledge. 

 It is a notable fact that nearly all of the mines are on the borders, 

 and that comparatively few ore localities have been found in the 

 interior of it. A reference to the map of the State, with this report, 

 shows the location of the mines and mine groups. The explana- 

 tion of their distribution is the greater accessibility of the outer 

 part of the region to lines of transportation and its more thorough 

 exploration. Prospecting for iron ore in the forested and more 

 distant interior is difficult, and besides, is not stimulated by any 

 hope of adequate return, excepting in case of large deposits which, 

 from their extent and character of ore, might warrant the con- 

 struction of branch railway lines, as at Chateaugay, Clifton, Jay- 



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

 t Thirty-second Annnal Report, N. Y. Scate Mu-eum, pp. 133-140. 



