REPORT OF THE DIRECTOR, 1922 135 
of the vein however are the noncontinuity of the banded parallel 
structures for any considerable distance and the box devolpment 
of the cellular structure. 
General Geology of the Area 
This locality marks a point along the contact of the syenite 
and the syenite-Grenville mixed gneisses, all of Precambrian age 
as can be seen by a study of the associated rocks of the vein; 
for we find that the country rock of the vein is the Grenville 
limestone, or what was once a limestone but now converted into 
various colored fine and coarse-grained marbles through the con- 
tact metamorphic action of the nearby syenites. 
Fall Brook 
Per we PIG EMSS COGS Ze 
DEE Ly 
sofeel 
Trecam brian 
Box — Ci ] G Ve E d F, Ae Pink 
“BOK” i d yYenvi ore e ma la] 
vein Gvenvill€ pmacbhle Gee ed Syen 
Fig. t Cross section through the “box-”vein and associated rocks, 
Lyonsdale, N. Y 
The box vein follows the strike and dip of the major foliation 
plane of the associated rocks which is for the former N 20° E 
and for the latter 40° W. 
Owing to the small amount of excavation in the search for 
boxes and chalcopyrite, only 40 feet of the vein are in sight along 
the strike and the width is about 11 feet. As fragments of the 
vein have been noticed on the south side of Fall brook it doubt- 
less follows along the strike and could be found there by further 
excavation. 
The rocks on the footwall of the vein consist largely of pink 
granitic syenite gneisses and greenish pyroxene gneisses with 
syenitic pegmatitic intrusions following the gneissic structures 
very closely. Of the origin of these rocks there can be little 
doubt, as we find so much of texture and mineral composition that 
is typical of igneous nature in them. In the pyroxene gneisses 
