58 " ECONOMICAL MINERALOGY. 



nesia, which, as well as the sulphate, is used for medicinal purposes.* By this operation, 

 when serpentine is employed, a large quantity of Venetian red is also procured, as that mineral 

 contains a considerable proportion of oxide of iron. This manufacture is now carried on near 

 Baltimore in Maryland, and there seems to be no reason why it may not be profitably pursued 

 in the vicinity of New-York. 



Serpentine, similar in every respect to that found on Staten Island and at Hoboken in New- 

 Jersey, occurs in considerable abundance in the counties of New- York, Westchester, Putnam, 

 Rockland and Orange ; and extensive deposits of the same mineral are also found in the county 

 of St. LawTcnce. 



The beautiful green colour of serpentine, and the fine polish which it takes when pure, give 

 it great value as an ornamental marble. When mixed with gi'anular limestone, it forms the 

 celebrated verd antique. Unfortunately in almost all the localities in the southern part of the 

 State, at least so far as they have been explored, the serpentine, although in gi-eat abundance, 

 is so mixed with carbonate of magnesia, asbestus and other magnesian minerals, as to render 

 it unfit to be worked as a marble. Thus a block obtained from a quarry in the county of 

 Westchester, concerning which high expectations had been raised, was found to have an un- 

 equal degree of hardness in its different parts, and to be filled with seams and nodules of other 

 magnesian minerals which could not be polished, or were too friable to sustain the rough usage 

 which is required for the dressing of marble. 



Dr. Emmons informs us that there are geveral localities in St. Lawrence county, in which 

 the soundness of the serpentine rock is remarkable ; and the only impediment to the introduc- 

 tion of this article for ornamental and useful purposes, he thinks, is the expense of transporta- 

 tion. At Pitcairn, is a fijie locality of verd antique. The colours are green and white, ar- 

 ranged in the usual forms of clouded marble. The serpentine has a bright green colour, and 

 belongs to the variety usually called precious. The carbonate of lime is white, and forms a 

 handsome ground for the translucent serpentine .t 



Usually associated with serpentine, when it occurs in extensive beds, is a mineral which 

 has nearly the same chemical composition, generally known by the name of soapstone. This 

 is particularly the case in the counties of Richmond and St. Lawrence. In consequence of 

 its softness and tenacity, soapstone may be turned or cut into articles of various shapes, and 

 rendered hard by exposure to heat. It is hence much used for the hearths of furnaces, the 

 sides of fireplaces, the linings of stoves, and for other similar purposes. 



Another substance often found with these magnesian minerals, is asbestus, under which I 

 include the variety composed of fle.xible silky fibres, sometimes known by the name of amian- 

 thus, there being no line of specific distinction to warrant its separation. This mineral has 



* Should the preparation of these salts of magnesia become important, the dolomites or double carbonates of lime and magnesia 

 which occur at Sing-Sing and elsewhere, may be'also advantageously employed for that purpose. The double carbonate is first 

 to be calcined, and then treated by sulphuric acid or sulphate of iron. There is thus formed an insoluble sulphate of lime and a 

 soluble sulphate of magnesia, which can be easily separated. 



t Emmons. New- York Geological Reports, 1838. 



