366 The American Geologist. J"°«' ^^^-^ 
ing points advanced by W. O. Crosby and M. L. Fuller* in 
support of the aqueo-igneous theory are all borne out by the 
character of the veins in question. They are: the occur- 
rence of rare minerals; the formation of large crystals ; the 
banding and comb structure of tourmalines, etc. normal to 
the walls ; water inclusions in the quartz ; and the occur- 
rence of pockets and druses. There is always one normal 
plutonic rock in every pegmatyte region, of similar but less 
acid character, from which the pegmatyte is evidently de- 
rived. The normal country granite apparently occupies 
this position here. 
In summary Van Hise says: "Pegmatization when it 
occurs on a great scale usually is found in connection with 
great intrusive masses in which there have been long-con- 
tinued composite intrusions. No great batholith is the re- 
sult of a single simple intrusion. The introduction of such 
masses went on irregularly through a very long time. Peg- 
matyte masses are not the result of a distinct epoch of 
eruption, but usually are produced in connection with the 
closing phases of igneous activity. * * * As the peg- 
matytes close to the central mass solidify, a large portion 
of the water is expelled and travels outward to help form 
the pegmatyte rock having a more distinctive vein char- 
acter." 
As before stated, the banded quartzyte very constantly 
forms the lower half of the Pala and Rincon pegmatitic 
veins. In explanation to this it is now suggested that this 
material first occupied the fractures in the cooling noryte 
boss as a hydrous magma, and that on crystallizing it con- 
tracted to approximately half its former volume. Toward 
the later stage of crystallization garnets developed, aided 
by contact action of the noryte, but were unable to reach 
any considerable size. Later a more aqueous magrria was 
forced up through the reopened crevices and formed the 
upper portion of the veins. The pockets seem to be of 
later origin. The crystallization in them of the residual 
rare elements as complex silicates and the occurrence of 
large quartz and orthoclase crystals supports this theory. 
1 Ckobbt, W O and Fullkr, M. L., Orgin of Pegmatite. Tech. Quar- 
Vol. 5, 1896, pp. 326-356. 
