128 GEOLOGY OP OLD HAMPSHIRE COUNTY, MASS. 



10 or V2 yards, having an easterly dip of 70° ; and tlience continues for an undeter- 

 mined distance, tlie surface of the ground not yet having been cleared of loose rocks 

 and of trees in such a manner as to define its extent. This branch vein has already 

 been sunk upon at this spot to a depth of 25 feet. Little or no emery is present. A 

 mass of at least 10 tons weight of the massive variety of magnetite lies loose in the 

 wood (with which the northern slope of the mountain is covered), 600 feet on the 

 direct course of this vein and near to an opening of what seems to be its direct con- 

 tinuation. The product of the latter excavation, however, is not the present massive 

 variety of ore, but this again occurs in quantity at the opening quite at the summit 

 of the South Mountain, forming a part of the great emery vein which there for a dis- 

 tance of several rods widens out to at least 15 feet. It here occurs in a series of 

 several more or less interrupted seams, often affording masses 6 or 8 inches thick and 

 quite pure, though in immediate proximity to the emery. 



The massive magnetite passes into the thin-veined where the seams are half an 

 inch and less in thickness, traversing the corundophilite or chloritoidal mineral, 

 among whose particles are frequent chinks or cavities constituting a very fissile 

 open rock. When these seams or veins become much broken or interrupted we have 

 what may be called the disseminated variety. All three coexist in the same vein and 

 often graduate insensibly to each other, the ore itself being in each variety entirely 

 identical. 



The stony magnetite exists in other places, and is disseminated in smaller grains 

 through a firmer gaugue, identical in character with that constituting the stony emery. 

 It is well seen at a place above referred to, where a vein has been worked upon 600 

 feet to the north of the summit of the North Mountain, and whence 50 tons of ore 

 have been raised for the furnace. It here exists in the proportions of 50 to 60 per 

 cent throughout the vein, which is 3 feet wide. As the vein is free from emery, it may 

 prove to be a prolongation of that bearing magnetite at the top of the mountain. 



Dr. Jackson has detected the presence of titanium in the emery of Chester, ren- 

 dering it probable that it will also be found in the accompanying magnetite. Should 

 this prove to be the case, it will only be in mere traces, and will probably increase the 

 value of the ore for iron making. It is quite certain that all the compounds, both of 

 sulphur and phosphorus, are entirely wanting throughout the formation. 



3. Corundum. 



This species consists of the well-known pure anhydrous alumina, and is rare 

 even in mines of emery. It is nevertheless occasionally found in those of Turkey, 

 occurring in the form of thin seams, small grains (often of a blue color), and rarely in 

 crystals diffused through the emery stone. It occurs rarely also at Chester, but thus 

 far has been met with only in seams or veins one-half or three-quarters of an inch thick, 

 though exhibiting a surface of nearly a square foot. It is grayish white, highly crys- 

 talline, like that from the Carnatic. The seams occur in the granular and compact 

 emery. 



