208 ON THE CHEMISTRY OF METAMORPHIC ROCKS. 



boron, fluorine, lithium, zirconium, and glucinum, are met with alike 

 in the oldest and the newest gneiss in North America. These 

 however, I regard as having been formed, like metalliferous veins, 

 by aqueous deposition in fissures in the strata. 



The above observations upon the metamorphic strata of a wide 

 region seem to be in conformity with the chemical princiciples 

 already laid clown in this paper; which it remains for geologists to 

 apply to the rocks of other regions, and thus determine whether 

 they are susceptible of a general application. I have found that 

 the blue crystalline labradorite of the Labrador series of Canada 

 is exactly represented by specimens from Scarvig, in Skye ; and 

 the ophiolites of Iona resemble those of the Laurentian series in 

 Canada. Many of the rocks of Donegal appear to me lithologi- 

 cally identical with those of the Laurentian period ; while the ser- 

 pentines of Aghadoey, containing chrome and nickel, and the 

 andalusite and kyanite-schists of other parts of Donegal, cannot 

 be distinguished from those which characterize the altered palaeo- 

 zoic strata of Canada. It is to be remarked that chrome and 

 nickel-bearing serpentines are met with in the same geological 

 horizon in Canada and Norway ; and that those of the Scottish 

 Highlands, which contain the same elements, belong t > the 

 newer gneiss formation ; which, according to Sir Roderick 

 Murchison, would be of similar age. The serpentines of Cornwall, 

 the Vosges, Mount Rosa, and many other regions, agree in contain- 

 ing chrome and nickel ; which on the other hand, seem to be absent 

 from the serpentines of the Primitive Gneiss formation of Scandina- 

 via. It remains to be determined how far chemical and mineral- 

 ogical differences, such as those which have been here indicated, 

 are geological constants. Meanwhile it is greatly to be desired that 

 future chemical and mineralogical investigations of crystalline rocks 

 should be made with this question in view ; and that the meta- 

 morphic strata of the British Isles, and the more modern ones 

 of Southern and Central Europe, be studied with reference to the 

 important problem which it has been my endeavour, in the present 

 paper, to lay before the Society. 



Montreal, January, 25, 1863. 



