MAGNETIC OXIDE OF IRON. 11 



Davenport's inn. It is contained in the gneiss or hornblendic gneiss rock, and follows its line 

 of bearing and dip. The ore is usually quite compact, and sometimes mixed with iron and 

 copper pjrrites. In some parts of this mine, which is a mile or more in length, the ore is so 

 highly charged with iron pyrites as to render it unfit for working, without the preliminary 

 process of roasting. 



There are here apparently three distinct deposits of this ore, scarcely differing from each 

 other, except in the proportion of iron pyrites which they contain. However much they may 

 resemble veins when on the surface of the rock, wherever they have been opened to any 

 extent, they are found to be parallel with the general stratification. 



Hornblende, both massive and in imperfect crystals, crystallized sphene, graphite, iron and 

 copper pyrites, carbonate of lime, green and blue carbonate of copper, and hyalite, are found 

 in immediate association with this ore, or in the rock in which it occurs. 



The Denny Mine is about three quarters of a mile south-southwest of the preceding, and 

 seven miles east of Philips' mill. It is situated on one of the crests of the eastern ridge of 

 the Highlands. The ore is usually compact and tolerably pure, but it is often largely mixed 

 with silica. It is strongly attracted by the magnet, and also possesses polarity. It is easily 

 reduced to powder, which, as usual, is black, unless when largely mixed with foreign matters. 

 The deposit is in beds or veins in gneiss, which, however, have a higher inclination than is 

 usual. Mr. Mather has correctly remarked, that the rocks on each side of the principal vein 

 are more or less traversed with thin veins of ore ; and it has been suggested, that the ore has 

 been injected into the cracks and crevices of the rock when broken by some upheave. 



The constituents of one of the compact specimens of this ore, are as follows : 



Magnetic oxide of iron, 89 . 00 



Silica, &c 11.00 



Besides silica, feldspar, and rarely carbonate of lime and asbestus, are associated with 

 this ore. 



This mine has been worked about thirty years ; and Mr. Mather states that about 600 tons 

 of ore are annually obtained from this and the other openings in the immediate vicinity. It 

 is used at the furnace at Cold Spring, and at some of the furnaces in Orange county, where 

 it is mixed with the ore from the O'Niel and Forshee mines. 



The Coal Grove Mine is about a mile and a half south-southwest of the Denny mine. The 

 vein, which is in gneiss, is narrow at the surface, but widens in descending. The ore is 

 represented as being of good quality, and well adapted to use in the forge. The mine is 

 nearer to the furnace and Cold Spring Landing than any of the preceding. 



To these may be added the Kemble Mine, a short distance north-northeast of the Coal 

 Grove Mine, and the Gouverneur Mine, four miles east of the Philips manor house, both on 

 the Philips vein ; neither of which, however, have been much worked. 



The Townsend Mine, which occurs in the Simewog hill in the town of Southeast, has 

 been opened for nearly half a mile, and has a course about northeast and southwest. This 

 is one of the earliest discovered and most extensively worked mines in this part of the State. 



