MINERAL RESOURCES OF THE STATE OF NEW YORK 3I 



masses could develop. The occurrence of serpentine and of chrysotile 

 is limited to the crystalline limestones which are foimd in belts and 

 in which the serpentine is disseminated in nodules, bands and small 

 particles in the midst of the carbonate minerals. The proportion 

 of serpentine to the whole rock is variable; in some places it may. 

 constitute the greater part but usually it plays a subordinate role, 

 being one of several impurities of the limestones. It is a secondary 

 product, formed in most cases by the alteration of a pyroxene 

 mineral. The asbestos is a variety of the serpentine that occurs 

 in small veins, rounded aggregates and irregular patches. It is apt 

 to be very irregular in its occurrence, but is sometimes rather 

 abundant within limited areas of the limestones. The fiber looks 

 like the commercial fiber of Canada and Vermont but seems to be 

 of lighter color and greater transparency. From the features of 

 its development it is regarded as a vein mineral, deposited in cracks 

 and cavities, by solutions circulating through the limestones and 

 probably derived from the disseminated serpentine which, as stated, 

 is an alteration of p5rroxene. 



Serpentinous limestones are not at all rare in the Adirondacks; 

 in fact they are rather common in the eastern part in Essex and 

 Warren counties and also in the northwest in St Lawrence county. 

 They are associated with the normal crystalline limestones, of which 

 they are only a special development, the serpentine itself having 

 no geological significance. In some places the rock has been quarried 

 as an ornamental stone, since the greenish serpentine particles 

 with the white or bluish dolomite base give a very pleasing effect 

 that makes the stone suitable for interior decorative work. Some 

 of the better known localities for these serpentinous marbles are 

 just north of Port Henry on Lake Champlain, in western Moriah 

 township, near Minerva and Oknstedville, all in Essex county, and 

 in the town of Thurman, Warren county. 



Wherever the serpentinous limestones are found asbestos may 

 be expected in greater or lesser amount, though of course as a 

 subordinate constituent. 



The principal occurrence of this nature that has thus far been 

 uncovered is in the town of Thurman, about 7 miles west of Thurman 

 station on the Adirondack branch of the Delaware & Hudson Rail- 

 road. There is a large area of crystalline limestone which here and 

 there contains bands charged with serpentine occurring as rounded 

 and irregular patches of some size but irregularly distributed and 

 as small grains that are more evenly scattered through the mass. 

 Such a band was prospected a few years ago, resulting in the produc- 



