IRON ORES OF THE CLINTON FORMATION 45 



is also to be inferred from the persistence of the beds along»the 

 strike. 



In the Oneida county area, on the other hand, though there is a 

 stretch of fully lo miles east and west in which the beds exceed the 

 minimum thickness stated, the conditions for mining on the dip are 

 generally less favorable. The average width of the area lying within 

 500 feet from the surface may be placed at 2 miles. The indicated 

 dip is here about 150 feet to the mile. 



With large scale operations the cost of ore extraction down to a 

 depth of 500 feet should not be much, if any, over $2 a ton. It 

 would appear that this limit is easily within range of "economic 

 mining for the near future, though with the large resources lying- 

 near the surface there will be no incentive to extend operations to 

 such a depth for many years to come. 



THE ORES 



Mineralogy and structural features 



The Clinton ores belong to the red, earthy variety of hematite. In 

 some specimens a little specular hematite is present, due to resolu- 

 tion and crystallization after the beds were laid down ; siderite 

 or iron carbonate also occurs locally in small amount distributed 

 in fine particles through the mass. The bulk of the ore, however, 

 consists invariably of amorphous hematite, red or brownish red 

 in color and streak. The specific gravity of the ore ranges between 

 the limits of 3.5 and 3.8. For purposes of calculation it may be 

 assumed that a cubic foot weighs 225 pounds. 



Compared with the hematites occurring in other surroundings, 

 the Clinton ores may be distinguished by certain structural pecul- 

 iarities, descriptive of which are the terms oolitic, lenticular, fossil 

 etc., that are applied to them in the various mining districts. These 

 structures are related to the methods of origin and arc singularly 

 persistent. 



An examination of representative specimens from the New York 

 beds brings out the fact that the hematite forms two kinds of 

 aggregates, each giving a distinctive character to the ores in which 

 it predominates. The one consists of s])herical or somewliat tlat- 

 tcned grains, quite uniform as to size and having the ai)i)earancc of 

 being solid hematilc. When separated from the matrix and l)roken, 

 or wlicn observed in thin section, it is usually scon that the grains 

 have a nucleus, generally a minute (|uartz kernel, about wliich the 



