Geological Siirvey of the State of Neio York. 81 



Prof. Emmons presents in his report a notice of much interest, 

 in relation to the iron ores of his district. Those of Essex county, 

 at Mclntyre, occur in vast abundance in the hypersthene rock ; 

 they are also found in the other primary rocks. They belong to 

 one variety, the octahedral or magnetic oxide, and occur in veins 

 of great extent. 



The peculiar connexion of trap dikes with these veins suggests 

 to Prof. Emmons an igneous hypothesis as to the origin of the ore. 



These veins in Arnold Hill, are crossed by a greenstone dike, 

 ten feet wide, which dislocates one of them four feet, and they 

 run north and south, making an angle with the direction of the 

 rock and red granite, which is northeast and southwest. The 

 Palmer vein is cut by four dikes ; one of them is fourteen feet 

 wide, and is traceable on the surface half a mile. This dike be- 

 ing pierced, a vein of ore thirty five feet wide was found, in close 

 contact with the dike and cleaving readily from it. 



The Winter ore has been cut through by nine dikes. 



The amount of the several veins in the vicinity of Clintonville 

 is one hundred and thirty six feet. The ores in the Sandford 

 mine, town of Newcomb, are in the hypersthene rock, and it 

 would appear, from the minute survey and description given, that 

 this ore is very superior, and the locality possesses advantages that 

 render it more available than any other works of the country. 



These ores have been wrought, and the iron made has been 

 submitted to comparative experiments by Prof. Johnson* of Phil- 

 adelphia, and found to be equal in strength to the best English 

 iron and surpassed only by the Russian. 



Prof. Emmons contrasts the position of the specular oxide of 

 iron of Jefferson and St. Lawrence counties, with the magnetic 

 oxide of Essex, and describes the association of the former as 

 follows : "The specular oxide may be (is) found in two geolo- 

 gical positions, — in the first it is associated with primary limestone 

 — in the second with gneiss, or some other primary rock beneath, 

 and the Potsdam sandstone above. In addition to the limestone, 

 serpentine is a common associate. It is sometimes in pure sepa- 

 rate masses, and in others, it is in intimate mixture and combina- 

 tion — giving in the first instance a spotted, and in the last a mot- 

 tled appearance to the rock." 



* See this Journal, Vol. xxxvi, p. 94. 

 Vol. XL, No, 1.— Oct.-Dec, 1840. 11 



