USEFUL MINERALS. 583 



cleavage and of the bedding appears to coincide. Near the falls of 

 the river, a short distance northward of the junction just noticed, the 

 slates give place to gray quartzite, which, with some beds of olive 

 slate, occupies the river-section to, and for some distance beyond, the 

 iron vein. 



The vein is well seen in the bed of the stream, and also in exca- 

 vations in the western bank, which rises abruptly to the height of 327 

 feet above the river-bed. In the bottom of the stream it presents the 

 appearance of a complicated network of fissures, penetrating the 

 quartzite and slate, and filled with a crystalline compound of tlie car- 

 bonates of lime, iron, and magnesia, which, from its composition and 

 external characters, I refer to the species Ankerite. With this mineral 

 there is a smaller quantity of red ochrey iron ore, and of micaceous 

 specular iron ore. 



In ascending the western bank of the stream, the vein appears to 

 increase in Avidth and in the quantity of the ores of iron. In one 

 place, where a trench was cut across it, its breadth was 120 feet. 

 Though its walls are very irregular, it has a distinct underlie to the 

 south, apparently coinciding with the dip of the containing rocks. As 

 might have been anticipated from its appearance in the river-bed, it 

 presents the aspect of a wide and very irregular vein, including large 

 angular fragments of quartzite, and of an olivaceous slate with glis- 

 tening surfaces. These fragments are especially large and abundant 

 in the central part of the vein, where they form a large irregular and 

 inteniipted rocky partition. 



That the reader may be enabled to understand the description of 

 this singular deposit, I give the composition of the various substances 

 contained in it, as ascertained by my own analyses and examinations. 



1. Specular Iron Ore, or nearly pure peroxide of iron, in black 

 crystalline scales and masses. 



2. Magnetic Iron Ore, a compound of the peroxide and protoxide of 

 iron. This and the first-mentioned ore, as they occur intermixed in 

 this vein, are capable of affording from 60 to 70 per cent, of pure iron. 

 Both of these ores have been introduced into the vein by igneous 

 fusion or sublimation. 



3. Ochrey Red Iron Ore. This is the most abundant ore in the 

 vein, and is of great value on account of its richness and easy fusibility. 

 It is also the material of which the mineral-paint produced by this 

 region is manufactured. It varies somewhat in quality, but the purest 

 specimens arc peroxide of iron, with scarcely any foreigir matter. 



4. Ankerite, or carbonate of iron, lime and magnesia. This is the 

 most abundant material in the vein, and is usually of a grayish-white 

 colour, though sometimes tinged red by the peroxide of iron. A 



