LOCALITIES OF SERPENTINE. ■ 69 



Whatever may be the final determination of the question in relation to the beds in Massa- 

 chusetts, there can be no doubt relating to the subject in the northern counties of New-York, 

 as no divisional planes can be detected in any of the beds which I have examined. It is 

 therefore an unstratified rock, so far at least as the limits of the second district are concerned. 



It will be observed that this rock occurs in thi-ee geological relations : 1st, in insulated beds 

 in granite, gneiss, etc. ; 2d, in beds of primitive limestone, with whicli it i.s also intermingled ; 

 and 3d, in those of the specular and magnetic oxides of iron. 



The consideration of these relations would bring up for discussion the period or age of the 

 serpentines ; whether, like granites, they belong to one or more periods. It is not clear whe- 

 ther we are to regard them as having been ejected at many difTerent periods, or not ; but from 

 analogy, and some few facts and phenomena which have been observed in Massachusetts and 

 northern New- York, the latter view seems tabe quite probable. The dislocations at the ore 

 beds, and the change in the sandstone which overlie those beds, are phenomena which very 

 clearly prove some remarkable changes subsequent to the deposition of this sandstone ; and 

 as serpentine is associated with these beds as constantly as trap dykes arc with those of 

 magnetic oxide of iron, and as there arc no intrusive rocks except the serpentine and specular 

 ore, we have reason to believe that the former had something to do in the production of these 

 derangements, or dislocations. All the proof, however, which exists here, is that the serpen- 

 tine was protruded after the consolidation of the sandstone ; inasmucli as it is raised up at 

 those places, and is highly charged with the peroxide of iron. 



Localities. The most important localities of serpentine are found in Pitcairn, Fowler, 

 Gouverneur, Edwards, Lewis, Moriah, and near Butlerfield's lake in Jefferson county. It 

 accompanies all the beds of primitive limestone ; and may be found too at most, if not all, 

 the ore beds in the northern counties. I have already spoken of a curious and interesting 

 variety, the porphyritic or brecciated serpentine, at the sterling ore bed, three miles and a half 

 south of Summerville in St. Lawrence county. I deem it unnecessary to go into a more 

 minute specification of localities in this place, as they will be given in the geology of the 

 different counties. 



Near Port Henry, an interesting substance is found, which resembles the primitive lime- 

 stone. The recent fracture, if made through a thick mass, reveals a surface which is com- 

 posed in the centre of limestone, serpentine, and a thin stellated mineral somewhat like talc. 

 It appears to be quite homogeneous ; but when decomposed, it leaves a remarkable scoria- 

 ceous skeleton, like a mass of porous lava, or tufa. This skeleton is composed of two distinct 

 substances, one of which has the hardness of serpentine, and the mammillated appearance 

 of chalcedony ; the other is soft, in little tufted masses arranged in zigzag lines which inter- 

 sect each other, and form thereby cavities lined with these small crystals : they appear like 

 talc. It is not remarkable that two or more minerals occur together ; but that the mass of the 

 rock should be composed in the way which is revealed by decomposition, is certainly worthy 

 of notice. Whether the scoriaceous skeleton was first formed, and then its cavities filled with 



