Origin of Pegmatite. — Crosbif and Fuller. 163 
ic structure'; (4) the finer crystallization next the walls, at 
least this is more suggestive of igneous contacts; (5) broken 
tourmalines, etc.; (6) inclined tourmalines; (7) inclusions of 
carbon dioxide; (8) immense size of many of the veins; (9) 
evidence of solution of the walls; (10) orientation of inclu- 
sions. The characters of the first list point unequivocally to 
the intervention of water in the formation of pegmatite; 
while those of the second list demand with equal distinctness 
important modification of the aqueous process. 
Igneous Theories. 
One of the earliest, and at the same time one of the clear- 
est and most satisfactory, statements of the igneous theory of 
pegmatite is that by Charpentier (1823). He held that the 
pegmatites are ''injections of granitic material, which, origi- 
nating in the still tluid granite, deep down, was pressed into 
the cracks of the already solidified granite above — afterbirths, 
as it were, of the same granitic formation in the district of 
which they occur." 
This idea was accepted by De la Beche, Bronn, Fournet, 
Durocher, and Angelot ; and Naumann* regarded it as the 
most probable theory. 
Brogger quotes Charpentier's view approvingly ; and his 
own paper, one of the most notable of the later contributions 
to the literature of pegmatite, is essentially a defense and far- 
ther development of this early igneous theory. He reviews 
critically the view^ of other writers, and argues strongly in 
favor of magmatic solidification, holding that it affords satis- 
factory explanations of the chief facts of composition, text- 
ure, structure, and relations to the inclosing formations. 
That water plays a more or less essential part in the form- 
ation of igneous magmas, at least those of acid character, is 
now so generally conceded that it would be idle to advance 
arguments against the view that pegmatite is the product of 
dry fusion. In fact it wo.uld probably be dilticult to prove 
that any of the so-called igneous rocks, have resulted from 
strictly anhydrous processes. The real question is, then, can 
acid pegmatites be regarded as the direct product of such a 
slightly aqueo-igneous fusi(»n or magma as yields the normal 
granites? It appears to the writers that a sufficient answer 
*Lehrbuch der Geognosie, 2d Ed., 2, 232 (1858). 
