88 Canadian Record of Science. 



ordinary temperatures, is absolutely untenable. On the 

 contrary, by closer investigation, it will everywhere be 

 found that each system of pegmatite veins of no matter 

 what variety, may in general be referred to a mass of plu- 

 tonic rock connected with it, and of closely related compo- 

 sition, and this quite independent of the nature of the wall- 

 rock. The veins may occur in the corresponding plutonic 

 mass itself, or within a certain distance outside it, but this 

 will generally exert little influence on their composition. 

 On the other hand the composition of the veins and that of 

 the allied plutonic mass will, as far as the principal ma- 

 terials are concerned, be very nearly identical (the rarer 

 pneumatolitic minerals which generally occur in small quan- 

 tities and which are formed by special processes, by " agents 

 mine'ralisateurs," are not considered here), and any local 

 variation in the mineral associates of the pegmatite veins 

 can, for the most part, be referred to peculiarities in the 

 composition of the mass with which the veins are con- 

 nected, and which they generally accompany as final and 

 contact products. 



If Credner's views upon the origin of pegmatite veins 

 cannot be accepted as correct, it is still possible that these 

 veins were deposited, as G. vom Rath concluded from his 

 observations upon the celebrated Elba pegmatite veins, from 

 solutions rising up from the depths. 1 The reason why 

 vom Rath did not attempt to account for the Elba pegma- 

 tite veins according to the older Charpentier-Naumann 

 theory, was this, " that tourmaline, beryl, lithia-miea, etc., 

 are foreign to normal granite " In comparing the Elba 

 veins with those of Brevig. " unequalled in their occur- 

 rences of minerals," and occurring in syenite, he further 

 remarks : " These veins, on account of their wealth in rare 

 and peculiar minerals, which for the most part are wanting 

 in the wall-rocks, necessitate the assumption of a special 



1 Gr. vom Rath, " Die Insel Elba" (Geogn.-min. Fragmente aus Italien, VIII) 

 in Zeitschr. d. d. geol. Ges. 1870, 22, 649 : r< While proposing the hypothesis that 

 the materials of the minerals in the veins of S. Piero have been brought up in 

 solution from the depths of the earth and not from the wall-rocks, we must 

 admit that many considerations are opposed to this view." 



