MINERAL ASSOCIATES OF SERPENTINE. 71 



Serpentine considered as a mining rock. 



In this country, few mines have been opened in this rock. In Pitcairn, a thin vein of galena 

 has been opened in it, and pursued some distance ; but it proved a total failure. In Edwards, 

 and in several other places, the specular oxide of iron has been found in it. In both of these 

 cases, however, the rock was a mixture of serpentine and limestone ; and so far as discoveries 

 have been made in the northern counties of New-York, no mineral deposit has been found 

 occupying exclusively the serpentine rock. In Troy in Vermont, however, a mine of the 

 magnetic oxide of iron has been wrought for several years. The ore is in a vein running 

 nearly north and south along the crest of a serpentine ledge for twenty-five or thirty rods. At 

 the working, the vein was ten feet wide at the top. As the work proceeded downwards, the 

 vein decreased in width. Traced to the south along the top of the ledge, it also diminishes 

 in the southern strike, and finally disappears, wedging out in the downward direction as well 

 as in that of its bearing. All the facts and phenomena furnished me at this place, correspond 

 with what I have observed in the mines which have been vwought in the primitive limestone. 

 It is, therefore, a rock which should require more than ordinary appearances, or temptations, 

 in order to induce the expenditure of capital in mines situated in it. A Boston company, in 

 consequence of overlooking the nature of the rock in which this mass of ore is situated, will, 

 in the course of a few years, be obhged to obtain their ore from some other quarter, as the 

 whole of the vein on which the iron works were estabhshed will be used up. We see what 

 a difference there is in the constancy of veins in serpentine and gneiss. Thus, at Peru, the 

 veins of the same ore penetrate downwards to the depth of two hundred feet, without any 

 variation of width ; while at Troy, the width has diminished one-third in twelve or fourteen 

 feet. I take the same view of serpentine as hmestone or trap, as a rock for mining : it is 

 imsafe, uncertain, and will result, in the end, in the entire loss of the capital invested. 



Before I close, however, I ought to make one exception in favor of the working of chromite 

 of iron. This mineral, which resembles so strongly the magnetic oxide of iron that it is often 

 mistaken for it, seems to be pecuhar to this rock, or rather to belong to it geologically. It 

 occurs in irregular shaped masses, and runs out in a mode similar to the magnetic oxide of 

 iron ; but it may occur in masses of sufficient extent to meet all the demands of commerce ; 

 but, if such large quantities were called for, as of iron ore, to supply a blast furnace, and 

 perhaps several, it would soon be exhausted. It is not, therefore, the great amount of this 

 ore in the rock, which gives safety to working it, but the small quantity required for the pur- 

 poses to which it is used. It is a remarkable fact, that while the serpentines of Massachu- 

 setts furnish chrome ore, those of the northern counties of New-York do not appear to contain 

 a trace of it ; and in this respect, we may perceive another difference in the serpentines of 

 the two regions. 



Mineral associates of Serpentine. 



Primitive limestone, in northern New-York, is the most constant rock in connection with 

 serpentine. The specular oxide of iron is also one of its common associates. Galena occurs 



