bansome.] SILVEK LAKE MINE. 153 
The ore of the Silver Lake lode is low grade, carrying very little 
gold. Although it has been "extensively stoped in the past, the main 
output of the mine is from the lodes of the second group. 
The New York City vein (or Whale-Rochester vein) is the most 
important of these, from the extent, regularity, and comparatively- 
high grade of its ore body. Its general strike is about N. 20° W., 
and its average dip is about 80° to the northeast. As to the Whale- 
Rochester vein, its upper portions were formerly extensively worked 
through an adit in Whale Basin. In the Silver Lake mine it has been 
worked through levels 1 and C, 300 feet apart, and by means of an 
intermediate level halfway between them. This lode is generally 
smaller than the Silver Lake, and has been less disturbed by post- 
mineral movement. The ore is generally fast, or frozen, to the walls, 
and is usually solid and unoxidized. In common with the other lodes 
of Group II the New York sometimes pinches to a very narrow and 
tight seam. This is well illustrated at the point where it is inter- 
sected by the crosscut on level C. It is here a stringer less than 
an inch in width, showing little indication of being part of a great 
productive vein. The chief value of the New York City vein has 
been found to lie northwest of the points where it is pierced by the 
crosscuts on levels 1 and C. In this direction it is stoped practi- 
cally continuously up to the Silver Lake lode. A typical section of 
the lode from the stope above level 1 is shown in fig. 3, page 67. As 
it approaches the Silver Lake lode it becomes smaller and more irregu- 
lar, and bends westward. It is also somewhat oxidized and stained. 
At the junction it passes into the Silver Lake with no other lines of 
separation than those due to later movement, and is usually defined 
b} 7 seams of gouge. From the point of junction westward the ore of 
the Silver Lake vein contains more chalcopyrite than is usual else- 
where, and thus resembles somewhat the ore of the New York City 
vein. The productive portion of 1 he New York City vein is cut by a 
fault about 750 feet south of its junction with the Silver Lake vein. 
The strike of this fault is apparently about N. 73° E., and it hades 
northerly about 15°. It has thrown the northern portion of the lode 
from 12 to 15 feet to the west. This fault was best seen in the stope 
above the midway level. Here the vein is cut off abruptly by a 
breccia zone about 6 feet wide which crosses the stope. The breccia 
is composed of sharpl} 7 angular fragments of country rock cemented 
by quartz, which carries a little ore, but is of too low grade to pay. 
Within the breccia zone are two or three fairly regular quartz string- 
ers. This occurrence is of special interest as showing that the depo- 
sition of quartz and ore was not confined to the period within which 
the important lodes were filled, but also took place at a later time. 
On the other hand, it seems very probable that this fault is older 
than the faults usually filled with soft, moist gouge, which have been 
described in connection with the Silver Lake vein. South of the 
