SILICA. 277 



line. It is very abundant ; may be obtained in large blocks, and when polished, has a per- 

 fectly black colour, and is highly esteemed for ornamental purposes. 



In the fissures of this serpentine, there are veins of tremolite, schiller spar, and other allied 

 minerals. 



At " Cotton rock " in Phillipstown, three and a half miles below West-Point, precious ser- 

 pentine occurs with veins of silky amianthus, whence the name of the locality. 



Richmond County. Serpentine passing into steatite, and containing veins and masses of 

 magnesite, asbestus, amianthus, talc, hydrate and carbonate of magnesia, is found at the 

 quarantine. Indeed it constitutes the main ridge of hills on the island, which extends from 

 New-Brighton to a little west of the village of Richmond, a distance of about eight miles. 

 According to Mr. Mather, this ridge ranges N. 20° E. and S. 20° W., and the prolongation 

 of the line of direction strikes the serpentine hills of Hoboken in New-Jersey. Through- 

 out its whole extent, this rock exhibits the diversified characters which are observed at the 

 Quarantine, or New-Brighton. This grouping of minerals, as in other cases, renders it quite 

 diflScult to distinguish the several varieties from each other. There are many intermediate or 

 transition states of these serpentines, which, in hand specimens, might be considered as dis- 

 tinct ; but an attentive examination of the locality will unfold their true character, and save 

 the chemist much labor and anxiety. 



Rockland County. Serpentine is found in grains and small masses in limestone, at several 

 localities. Some of these have been noticed under the head of Marble (page 70). I am not 

 aware that pure serpentine has been found in masses of any considerable magnitude. 



St. Lawrence County. This mineral, in almost every variety, is very abundant in this 

 county. In the form of verd antique, it is found in the towns of Gouvemeur, Fowler, 

 Edwards and Pitcairn (see page 70) ; while the variety soapstone is abundant in the towns 

 of Edwards and Fowler. Indeed, in most of those places where the true serpentine is found, 

 it passes into the softer varieties of steatite (soapstone), or into that mixture of pyroxene and 

 steatite which Dr. Emmons has called Rensselaerite. 



The crystallized variety, and the precious serpentine of a light green colour, occur in 

 the immediate vicinity of the village of Gouvemeur ; and the same mineral in the massive 

 form is found associated with calcareous spar, at Morris' natural dam, about two miles from 

 that place. It is sometimes of a yellowish green colour. 



In the vicinity of Gouvemeur, crystals are also found, which have the form of scapolite 

 in several of its modifications, but which appear to consist chiefly of serpentine or steatite. 

 In accordance with the general views which have been drawn from the analysis of several 

 supposed pseudomorphs of hornblende, pyroxene and spinelle, it is more than probable that 

 these crystals are composed of a portion of the constituents of scapolite, another part of which 

 has been replaced by serpentine or steatite. The only change necessary for this purpose, is 

 the removal of a part of the alumina and lime, and the substitution of magnesia. 



The serpentine at Gouvemeur is frequently also replaced by the fibrous and radiated form 

 of steatitic pyroxene, which is so frequently met with in this and in Jefferson county. 



