SILICA. 275 



cut and turned on a lathe. It is of various colours, from a very light green to nearly black, 

 and is susceptible of a fine polish. Large blocks have been quarried at this locality, entirely 

 free from checks and flaws which so often render this material valueless. 



New- York County. On the Hudson river, near the city, there is a large bed of serpentine, 

 with veins of amianthus ;* while the same mineral, entirely resembling that at Hoboken, is 

 frequently found in bowlders in the southern part of the island. Dr. Gale states that these 

 bowlders are rare in the northern part of the island. 



Onondaga CotJNTy. On the hill a short distance east of the mansion of Major Burnet at 

 Syracuse, there is a dyke or bed of serpentine, more or less mixed with limestone, and having 

 various shades of colour, as bottle green, greyish green, and nearly black. 



These serpentines were first noticed by Mr. Vanuxem, and described by him in his report 

 of 1839, and he considers them new varieties for our country. " Some have a peculiar 

 appearance, like bronze, owing to small gold-like particles with a lamellar structure, resem- 

 bling bronzite or metalloidal diallage. There are also other particles highly translucent, like 

 precious serpentine, with frequently small nuclei resembling devitrifications or porcellanites, 

 coloured white, yellow, blood-red, variegated, etc. The grain of this kind is like common 

 serpentine. In other kinds, the mass seems to be made up of small globuliform concretions, 

 varying in size, being centres of aggregation. Some are of dark vitreous serpentine, others 

 , are of the compact kind, the enveloping part being of a lighter colour."t 



These principal varieties produce endless mixtures upon the small scale, and numerous 

 differences in the shades of colour. 



According to Mr. Vanuxem, these serpentines seem to resemble the ophiolites of Tuscany ; 

 and should the views of Brocchi be correct, they may not only be similar in origin, but in age. 



In regard to the chemical nature of these minerals, I have observed that all the specimens 

 contain a large admixture of carbonate of lime. They almost all effervesce freely in acids ; 

 but there is always a nucleus of serpentine. The specimens are susceptible of a polish, and 

 when sufficiently compact, and free from seams, exhibit in a striking manner the great variety 

 of colours which the mineral possesses. 



Orange County. There are several localities of serpentine in the towns of Cornwall, 

 Monroe and Warwick. In the Forest of Dean in Cornwall, it is yellow and dark yellowish 

 green, in imperfect crystals and grains, in white limestone. 



The common variety of a dark colour is found associated with magnetic iron ore, at the 

 O'Neil and Forshee mines in the town of Monroe. The quantity, however, is small. 



There are several localities of the crystallized, massive and disseminated varieties in the 

 tovra of Warwick. One of the most interesting of these is about two miles south of the 

 village of Amity. It is found here in imperfect crystals, which are grass-green, yellowish 

 green, and nearly black. The crystals are sometimes two and a half inches long and one 

 and a half broad ; and Dr. Fowler has noticed some, probably from the same locality, which 



* J. Van Rensselaer. Americm Jounud of Science. XIV. 192. t Vanuxem. New-York Qeological Reports, 1839. 



