MAGNETITE IRON DEPOSITS OF SOUTHEASTERN NEW YORK 113 
are about 700 feet apart. The Sackett shaft is said to be 75 feet in 
depth, but both shafts contain water and are now inaccessible, and 
in many places the cuts are partly filled by caving. (See plate 15, 
figure 1.) 
Putnam*”’ states that the ore body in the Sackett mine was 
reported to be 5 feet in width, and in the Pratt mine from 2 to 4 
feet wide. A sample taken from a pile of 175 tons of ore carried 
57.23 per cent iron and 0.663 per cent phosphorus (Putnam, op. cit.). 
The dip of the rock structure is almost vertical, varying between 
85° and 90° to the southeast; the strike is about north 40° east, and 
the gneissic structure of the rocks in the walls of the cuts pitches 
steeply (45°) to the northeast. 
There are two cuts along the Pratt workings, each about 150 feet 
long. The northernmost cut shows Pochuck granite in the hanging 
wall, in places; the rock immediately in the vicinity of the workings 
is Pochuck-Grenville, heavily intruded with the Pochuck granite; 
the walls are in part syenite-soaked Pochuck-Grenville. 
The ore is banded in part, and in part disseminated, grading into 
the walls, and is associated with the dioritic phase of the Pochuck. 
The Denny mine. This mine is the extreme southwest member 
of the Canada Mines group. The openings were apparently made 
along two or three “pods” or “lenses”’ of ore, for greater irregu- 
larity is shown than at the other mines (see plate 15, figure 2). 
These occurrences were about 20 feet wide in the widest part and 
possibly two or three times as long. 
Here there is much Pochuck granite cutting Pochuck-Grenville 
(see plate 3, figure 2), and in places little “dikes” or “ veins” of 
magnetite are associated with, and cut the extremely acid Pochuck 
granite itself, representing overlapping stages of the magmatic end- 
stage period. 
Very little ore was taken from this mine, and no exploratory work 
has ever been done excepting the openings just described. The 
extent of this and of the related ore bodies is not known, but judg- 
ing from the data that are available, the persistence of the belt, and 
the general geologic relations, it seems probable that these old mines 
are capable of furnishing a large amount of ore provided proper 
methods of mining and concentration be used. None of the mines 
has been in operation since 188o. 
About three-fourths of a mile southwest of the Denny workings, 
along the same belt, there is a small group of shallow pits which 
17 Putnam, B, T, Tenth Census Report, 1880, 
