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IV. " On the Serpentines of Canada and their associated Rocks/' 

 By T. STERRY HUNT, Esq., of the Geological Survey of 

 Canada. Communicated by THOMAS GRAHAM, Esq., F.R.S., 

 Master of the Mint. Received February 26, 1857. 



The origin and formation of serpentine is still regarded as an 

 unsettled problem by chemical geologists, and Sir William Logan 

 having shown from structural evidence the undoubted stratified cha- 

 racter and sedimentary origin of the serpentine of the Green Moun- 

 tains in Canada, I have been induced to make a chemical and mine- 

 ralogical investigation of these serpentines and the rocks associated 

 with them. In the present note I propose to indicate briefly some 

 of the results obtained, reserving for another occasion the details of 

 my examination. 



The serpentines of the Green Mountains, which have been traced 

 for 150 miles in Canada, have been found by Sir William to belong 

 to the upper portion of the Lower Silurian system, whose disturbance 

 and metamorphism have given rise to the great Apallachian chain, 

 of which the Green Mountains are the north-eastern prolongation. 

 These mountains are composed of gneissoid, micaceous, argillaceous, 

 talcose, and chloritic schists, with quartzite, limestone, dolomite, 

 serpentine, pyroxenite, and the other rocks about to be mentioned. 



The serpentines, which form immense beds, and often cover large 

 areas, are sometimes homogeneous, and at other times conglomerate 

 in their character, the cement being a ferruginous dolomite, or more 

 rarely a carbonate of magnesia, exempt from lime but containing 

 carbonate of iron. In some cases the serpentine is intimately mixed 

 with a large amount of carbonate of lime. Chromic and magnetic 

 iron, ilmenite, diallage, with the ordinary lamellar and fibrous varie- 

 ties, picrolite and chrysotile, are common in these serpentine rocks. 

 The results of a great number of analyses show a uniformity of com- 

 position in all the serpentines of this formation, and also show a 

 curious fact hitherto overlooked, that of the constant presence of a 

 small portion of nickel, never exceeding a few thousandths. I have 

 never failed to detect it in any variety of serpentine from this forma- 

 tion, not only in Canada, but in the States of Vermont, Connecticut, 

 and New Jersey. Its presence seems still more widely spread, for I 

 have also found nickel in serpentines from California, the Vosges in 



