THE MINING AND QUARRY INDUSTRY 1914 13 



the limestones. The fiber looks like the commercial fiber of Canada 

 and Vermont but seems to be of lighter color and greater trans- 

 parency. From the features of its development it is regarded as a 

 vein mineral, deposited in cracks and cavities, by solutions circu- 

 lating through the limestones and probably derived from the dis- 

 seminated serpentine which, as stated, is an alteration of pyroxene. 



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 town- 

 ship, near Minerva and Olmstedville, 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 Thur- 

 man station on the Adirondack branch of the Delaware & Hudson 

 Railroad. 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 distrib- 

 uted and as small grains that are more evenly scattered through the 

 mass. Such a band was prospected a few years ago, resulting in the 

 production of a small quantity of chrysotile or serpentine asbestos. 

 The latter occurs principally within a small but rather persistent 

 zone of the limestone that takes a northeasterly course parallel to 

 the general structural trend. Within this zone occur numerous 

 veinlets that carry a very light, silky asbestos of a maximum 

 length of about an inch, most of which is apparently of good 

 quality. The veins are not persistent, but thin quickly and merge 

 into the massive serpentine of the country rock. Outside the main 

 zone, bunches of serpentine are to be seen which are shot through 

 with fiber, or show the presence of whitish asbestiform material. 

 The general average of the fiber is probably not more than one- 



