42 Canadian Record of Science. 



dal the innumerable pegmatite veins occur as regular veins 

 not only in the contiguous granite with which they are 

 genetically connected, but also in various crystalline schists. 

 The conditions at Hittero have already been mentioned. I 

 think I may assert that probably very few geologists have 

 seen so many and such various occurrences of pegmatite as 

 I have, 1 and, according to my experience, pegmatite veins 

 occur at least as abundantly outside the boundaries of the 

 corresponding eruptive rock as within it. Any theory with 

 regard to the formation of pegmatite must therefore, in the 

 first place, be able to account for the true vein occurrences 

 which are completely independent of the wall rock, with- 

 out at the same time losing sight of their close relationship 

 with the scattered pegmatitic druses. 



J. Lehmann, 2 in his large and excellent work upon "The 

 Granulite District of Saxony," endeavours to account for 

 the pegmatite veins of that district. He starts out with 

 the "hydatopyrogene" formation of granite, and pronounces 

 the veins in a sense to be injection veins ; with complete 

 correctness, he distinctly emphasizes the fact that their 

 feldspar, etc., has not been deposited from ordinary per- 

 colating water. " The granitic veins of the granulite dis- 

 trict have originated, no doubt, with the aid of more or less 

 water, but this has not been atmospheric water which has 

 percolated downwards through the cracks of the granite, 

 but it is eruptive water, which was given up from the 

 granite to the surrounding rocks, and which, under peculiar 

 conditions obtaining at great depths,was supersaturated with 

 mineral matter." Lehmann assumes for the granitic magma 

 a gelatinous consistency, which was to be accounted for 

 presumably by the presence of " viscous silicic acid." 

 " These fluid secretions of granite may be compared to hot 

 jelly." . . . " The capacity of silica to form jellies 

 with much or with little water invites strongly to this hypo, 

 thesis." " Between such a gelatinous magma 



1 Th. Scheerer remarks (Pogg. Ann. 1842, 56, 493), that pegmatite veins" may 

 be met with in Norway (and also in Sweden) in greater frequency than in other 

 countries." 



2 Granulitgebirge, p. 52-58. 



