74 NEW YORK STATE MUSEUM 
PART 4 
THE MAGNETITE MINES 
This section is devoted to descriptions of the individual mines, 
including equipment, extent of workings, chemical character of the 
ores, character of the walls, tonnage of ore produced, special struct- 
ural features, and all other items of interest which it has been possible 
to obtain. Many of these properties have been closed down for al- 
most half a century and information with regard to them is difficult 
to gather. 
The magnetite deposits in southeastern New York mined up to 
the present time have furnished shipping ores carrying from 50 to 
60 per cent iron. Although these are not yet exhausted the main 
supply for future mining consists of leaner ores carrying a minimum 
of 25 per cent iron, which can be worked on a very extensive scale 
and which will lend themselves readily to magnetic concentration. 
The richer magnetites, with some few exceptions like the Forest 
of Dean ore body, occur in irregular tabular masses 10 to 25 feet 
thick at most, and consequently the limit of exploitation of these 
deposits was reached at comparatively shallow depths under the 
conditions of mining that formerly obtained in the district. The 
aggregate output of shipping ore has been approximately 10,000,000 
tons. 
The only mines now in operation are the Lake, the Scott and 
Cook of the Sterling group, and the Forest of Dean mine. The 
Tilly Foster, Mahopac, and Croton magnetic mines ceased operation 
in the nineties ; the others closed down in 1880 and have never been 
in operation since with the exception of the small mine at Travis 
Corners, formerly called the Nelson, later the Canopus. Attempts 
have been made from time to time to operate this mine, without 
much success. 
None of these mines has ever been bottomed, although some of 
them have been in more or less continual operation since 1750; in 
most cases the supplies of ore have not been seriously drawn upon, 
and provided the mines now inoperative have ore bodies as persist- 
ent in depth as those now in operation, it seems reasonable to con- 
clude that the magnetite ore bodies in this area form an ore-reserve 
of very considerable tonnage and value. 
