raxsome,] SILVER LAKE MINE. 151 
Anglesite and eerussite wore found associated with the galena in 
these upper levels, but never formed a very large proportion of the 
ore, of which the important bodies, even in these upper workings, 
wen' chiefly galena. 
Movements within the Silver Lake lode subsequent to the deposi- 
tion of the ore may be conveniently divided into four classes, (1) 
faults cutting the lode obliquely and at a considerable angle with the 
horizontal; (2) strike faults essentially parallel with the lode; (3) 
strike faults making a considerable angle with the plane of the lode, 
and (4) irregular fracturing. Those of class 1 will first be described. 
(1) A close inspection of the sent Invest or foot wall of the Silver Lake 
vein shows that it is cut at frequent although irregular intervals by fis- 
sures, usually of small width. It is seldom possible in such cases to 
determine accurately the general course of these fissures. Fissures are 
never geometrical planes, and an observation made on a fissure exposed 
in the walls of a drift may give figures differing very much from the 
general or average course of the dislocation. The observed courses of 
these fissures give directions varying from north and south toN. 55° W. 
In general, they appeal- to form a system essentially parallel with the 
productive lodes of Group II, such as the New York City and Royal. 
Their dip is usually to the southwest at a high angle (over 70°), but 
there are a few notable exceptions. The fissures vary from narrow 
cracks up to openings ;t fool wide. In a few cases they are filled with 
solid quartz, carrying a little ore. These last are not known to cut 
the Silver Lake lode. They air probably of the same age as the lat- 
ter and are comparable, in all respects save size, with such veins as 
the E. G. S. and L. A. S. of Group II. .Most of these fissures, how- 
ever, are filled with aclay seam or gouge of varying thickness, some- 
times containing broken vein quartz. These fissures cut through the 
Silver Lake lode and are t herefore younger. They record disturbance 
subsequent to its format ion. They have not influenced the productive- 
ness of the latter to any known extent, but are well known and care- 
fully watched by the miners on account of their misleading tendency. 
Experience has shown that a miner, on running upon one of these cross 
seams, is wvy likely to follow it into the hanging wall, leaving, 
unknowingly, the main lode on his left. The presence of broken 
quartz mixed with the gouge 1 of these seams shows that in some cases 
they record fresh movement along preexisting fissures which had 
become filled with quartz. The actual result of movement along these 
post-mineral fractures is present as gouge, but the net displacement 
seemsto have been always small. It is usually impossible to detect any 
actual faulting of the main lode where crossed by these later fissures. 
On Level A, southeast drift, a set of fissures occurs which, while 
apparently belonging to this system, are of unusually flat dip, in one 
case as low as 20°. The direction of dip is easterly. The vein itself 
is very irregular southeast of the first of these faults and is, chiefly a 
breccia of country rock cemented by quartz and low-grade ore. It is 
