MAGNETITE IRON DEPOSITS OF SOUTHEASTERN NEW YORK SI 
mine was worked by an open cut, from which a short inclined tun- 
nel was driven into the hanging wall. Cross-folding is exhibited in 
the rocks exposed in this cut. 
The lower ore-horizon. Swinging around the base of the hill 
at the foot of Sterling lake, on the southwest, south and southeast 
sides, with strikes and dips shifting in accordance (see fig. 6), 
lies the lower ore-horizon; this has been offset by the same fault 
which affected the Tip-top mine, of the upper ore-horizon. 
The Summit mine. Beginning at a point about 1500 feet west of 
the boiler house of the Lake mine is an opening on the west side of a 
narrow little gulch lying between two hills. An inclined shaft fol- 
lows the dip of the rock, or ore, easterly, terminating at an unknown 
depth. This is the slope leading into the old Summit mine, now 
filled with water. The rock structure strikes north 5° east and dips 
30° a little to the south of east. There are numerous old prospect 
pits in the vicinity but it is impossible to judge from the surface 
conditions how extensive the workings may be, or the size of the 
ore body. 
Crossing the strike of the rocks, from the Summit mine to the 
Lake and Sterling mines, the same general direction of dip is main- 
tained without reversal, so that the slope of the Summit mine, if 
extended at the same inclination, would pass about 200 feet under 
the Lake and Sterling mines (see figure 7). No mention is made 
of this mine in the old reports, and no information is at hand with 
regard to the extent or character of the ore. The country rock in 
the vicinity does not differ from that connected with the Lake ore 
body. 
The Upper California mine. About 1500 feet south of the Tip- 
top mine, and at the base of the hill, the slope of the Upper Calli- 
fornia mine taps the lower ore-horizon at an angle of 30°. The 
slope was sunk to a depth of 350 feet on the incline before opera- 
tions ceased. The mine is now full of water and inaccessible. 
On the dump were found fragments of Pochuck-Grenville, Pochuck 
granite, dioritic and syenitic pegmatites, and massive and coarsely 
crystalline magnetite. Petrographic study of some of the material 
collected from the dump shows: 
a Magnetite; with remnants of quartz, feldspar and pyroxene, 
corroded, embayed and replaced by the magnetite, the feldspars all 
having strongly sericitized borders where in contact with the mag- 
netite. 
b Syenitic phases of the Pochuck, carrying colorless pyroxene, 
antiperthite, plagioclase, and magnetite in end-stage relations. 
