8O NEW YORK STATE MUSEUM 
grained massive magnetite, which contains, in common with all the 
magnetite ore bodies, remnants of still unreplaced minerals, and 
minerals of similar origin to the ore itself, such as apatite. In the 
“slip-zone” there are occasional occurrences of coarsely crystalline 
magnetite, but these are rare. 
Closely associated with the ore and forming parts of the walls is a 
coarse red hornblendic and pyroxenic pegmatite; the dioritic phase 
of the Pochuck pegmatite. Sometimes included within the ore, rim- 
med with coarse biotite at the contact, sometimes lying between the 
ore and the wall rock, sometimes cutting the ore, this pegmatite and 
the ore are very closely associated and essentially contemporaneous 
in origin. 
The ore does not uniformly follow the structure in the rock, as 
stringers of ore cut across the rock structure in places, and fre- 
quently split and divide, the stringers of ore in such cases commonly 
pinching out and fading into rock, in a manner shown in figure 4 
sketched in the main slope toward the bottom of the mine. In other 
places the ore follows more or less regularly the secondary corruga- 
tions called “ rolls,’ as shown in figure 5, sketched at the north end 
of no. 6 drift on the 2800-foot level. 
According to figures obtained at the mine, first-class shipping ore 
will carry 61.34 per cent iron, 0.60 per cent phosphorus and 5.20 per 
cent silica; this is probably a little better than the general average 
composition of the ore. Putnam, in the Tenth Census Report, gives, 
as an average of 50 tons, 57.25 per cent iron, 1.205 per cent phos- 
phorus and 0.088 per cent sulphur. The output from the Lake 
mine up to and including the year 1917 was 1,254,283 tons of mag- 
netite. 
The Tip-top mine. From a small opening on the summit of the 
hill immediately south of the Lake and Sterling mines, and distant 
from them less than 1000 feet, a little ore has beeen taken in the 
past. This mine, called the Clarke or Tip-top mine,’?® ceased oper- 
ations some time between 1880 and 1889. From structural relations 
shown in the field it is judged that this small body of magnetite, 
much of which has been mined out, is a small portion of the Lake 
ore body, displaced by a fault of small throw. In the Tenth Census 
Report, Putnam states that the ore carried 54.03 per cent iron, 0.173 
per cent sulphur, and 1.751 per cent phosphorus; quite similar in 
composition to the ore from the main body of the Lake mine. The 
126 Putnam, in the Tenth Census Report, apparently confused this mine with 
another opening on the lower horizon of ore, called the Summit mine. 
