MAGNETITE IRON DEPOSITS OF SOUTHEASTERN NEW YORK 85 
may be seen in one of the trenches, which crosses the strike of the 
ore body at an angle, where the magnetite distinctly cuts across the 
regional structure of the rock. 
Although in places dip-needle readings show a band of ore 75 
feet wide, this is simply a zone of disseminated magnetite. The ore 
is lean and streaky. 
Petrographic study of samples of the ore taken from various pits 
proves the material to be modified Pochuck-Grenville, carrying con- 
siderable granular pyroxene, andesine, antiperthite, quartz and 
magnetite. 
The magnetite, associated with and related to the quartz, cuts, 
corrodes and replaces the silicate minerals and occurs in a banded 
fashion suggestive of a sort of lit-par-lit arrangement, although the 
bands or streaks of magnetite, with quartz, are not the result of 
simple injection. 
It is possible that a very considerable tonnage of lean ore suitable 
for concentration might be furnished by the exploitation of this 
“ mine,” 
The Crawford mine. This mine was located in 1792 on what 
is commonly thought to be the northern extension of the same sub- 
sidiary belt of ore in which the Steel mine was subsequently opened. 
The writer is inclined to question this generally accepted relation 
because the form and habit of the ore bodies are not similar, their 
petrographic characters are unlike, and because the valley trenched 
in the ridge in which the two deposits lie, and which separates them, 
is established on a line of weakness of sufficient prominence to exert 
structural control of erosion, so that a valley was developed across 
an otherwise continuous ridge of hard rock. Moreover, the ore 
body in the Brennan pit (see fig. 8) is abruptly cut off, by reason, 
probably, of a fault along the valley, in conjunction with a smaller 
fault which offsets the Crawford ore body also to a small degree. 
It may be, therefore, that the Steele and the Crawford mines, while 
apparently opened along the same body of ore, are in reality in two 
different ore-bands lying approximately in the same line, but sepa- 
rated by the fault postulated. Not sufficient field work has been 
done to prove this, however. 
In 1880, 2240 tons of ore were hoisted from the mine, averaging 
57.06 per cent iron, 2.004 per cent phosphorus and 0.178 per cent 
sulphur.’** The mime was first worked by means of a pit, which 
now leads into an underground drift, following the pitch of the ore 
128 Putnam, B. T. Tenth Census Report, 1880. 
