APLITE, PEGMALITE, AND TOURMALINE 193 
and in several instances veinlets of twelve and more inches long 
of tourmaline-felt (fine acicular tourmaline), as much as an eighth 
of an inch in width, have been noted in the granite in the north- 
west quarries of the ridge. While no distinct evidence bearing 
on the contemporaneous origin of the tourmaline aggregates in 
the granite with those of the pegmatite and the tourmaline vein- 
lets, it seems reasonable to assume such contemporaneity. 
The very nature of the areas oppose the hypothesis of direct 
secretion out of the eruptive granite magma. On the other 
hand, the characteristic mode of occurrence and intimate rela- 
tionship to certain other mineral species present, as shown both 
macroscopically and microscopically, make it reasonably certain 
that the tourmaline areas have resulted from fumaroles highly 
charged with boric acid acting on the feldspars and mica. 
Tuomas L. Watson. 
GEOLOGICAL LABORATORY, DENISON UNIVERSITY, 
Granville, Ohio. 
