MAGNETITE IRON DEPOSITS OF SOUTHEASTERN NEW YORK 87 
to an extension of this fault, and in part due to a second fault which 
is responsible for the development of the small valley between the 
ridge on which the Steele mine lies to the south, and the ridge in 
which the Crawford and Brennan mines were opened. 
The fault which offsets the Crawford ore body and which trends 
a little to the south of west is not of sufficient magnitude to cut off 
the ore body in the Brennan pit entirely, but in conjunction with 
the larger fault, striking approximately north 50° west, and along 
which the valley mentioned has developed, thus showing this direc- 
tion to be one of greater weakness, it is reasonable to expect the 
ore to be entirely faulted out as seems to be the case (see fig. 8). 
There are no further data available on this particular body of ore. 
The Red-back belt. Less than a mile west of Tuxedo lake, a 
more or less regular, straight band of ore extends for over 5000 
feet, striking north 10° east, dipping from 43° to 46° in a south- 
easterly direction and pitching toward the northeast about 10°, 
although this may be variable. 
The ore-band may be traced along the surface by the rusty red- 
dish outcrop, due to the oxidation of pyrite and pyrrhotite, the color 
of the outcrop giving the mine its name. The Red-back mine was 
opened on the south end of this ore-belt, which was discovered in 
1780 by J. Stuperfell’*®. The ore is not over 10 or 12 feet thick in 
most places, and it carries a very appreciable quantity of sulphur 
in the form of pyrite and pyrrhotite. According to Putnam’ the 
average composition is as follows: 52.93 per cent iron, 0.028 per 
cent phosphorus, and 3.603 per cent sulphur. In 1880, 3638 tons of 
ore were mined, but the mine was soon thereafter abandoned. It 
was worked through openings along the strike for 500 feet, and the 
ore was followed down the dip by an inclined shaft, stated to be 
about 300 feet deep, now inaccessible because of water. Ruins of 
the old skipway still remain and parts of the rails may be seen in 
the slope; an old circular roaster, rusty and dismantled, stands near 
the incline, so that the ore was evidently roasted on the ground. 
Roll structures are prominent in the footwall of the mine, judg- 
ing from the evidence presented on the surface. Both walls are 
modified Pochuck-Grenville at the entrance to the slope, heavily 
injected with coarse, biotitic and hornblendic pegmatite (dioritic 
facies of Pochuck), more especially prominent in the footwall at 
this point. Here also the footwall contains so much sulphide that 
130 Appendix to 3d Annual Geologic Report of the First Geological District. 
Doctor Horton’s report to W. W. Mather, 18309. 
131 Putnam, B. T. Tenth Census Report, 1880. 
