12 NEW YORK STATE MUSEUM 



of the Canadian mining industry which supplies the larger share of 

 the world's needs of the material. The principal mines of Canada 

 are situated in the province of Quebec, on the south side of the 

 St Lawrence river, not very remote from the northern boundary 

 of New York. The district in fact extends southward across the 

 Vermont line, in which state there are similar occurrences which 

 have more or less importance. 



The proximity of the Adirondack crystalline region to that dis- 

 trict might be regarded as favorable to its carrying the same kind 

 of deposits, but there is really no basis for such inference as a little 

 consideration will show. The asbestos of Canada and Vermont is 

 found within a belt of metamorphosed Paleozoic formations which 

 lie along the flanks of the Green Mountain uplift. The particular 

 home of the mineral is in serpentine, in this case the product of 

 alteration of old igneous rocks originally composed of minerals of 

 the olivine and pyroxene groups. A large number of serpentine 

 bodies are known in the stretch from southern Vermont into and 

 across the eastern townships of Quebec, but in only a few is 

 asbestos present in workable proportions. The mines or quarries 

 are based on masses of serpentine that carry closely crowded vein- 

 lets of chrysotile, the latter occurring in such profusion as to per- 

 mit the excavation of the whole mass, from which the fiber is then 

 obtained by hand picking or by milling operations. 



No similar bodies of serpentine are found in the Adirondacks. 

 The latest igneous intrusions in that region took place before the 

 opening of the Cambric period, and the sedimentary formations 

 were laid down at a much earlier date. The igneous intrusions 

 did not include any rocks of the peridotite class (composed of 

 olivine) and consequently there has been no material from which 

 large serpentine masses could develop. The occurrence of ser- 

 pentine and of chrysotile is limited to the crystalline limestones 

 which are found in belts and in which the serpentine is dissemi- 

 nated 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 occur- 

 rence, but is sometimes rather abundant within limited areas of 



