6 Bulletin of the New York State Museum. 



The magnetic iron ore has not been found distributed uniformly 

 throughout the Highlands. There appear to be certain ore ranges 

 or belts, in which the larger and more productive mines are opened. 

 There are mine groups also, as the Sterling Iron and Railway Com- 

 pany's mines, the Greenwood mines, in Orange county; the Todd- 

 Croft and Sunk mines, and the Croton-Brewster ranges in Putnam 

 county. The boundaries of these ore-bearing belts and the inter- 

 mediate barren territory, have not been determined, since the explora- 

 tion has been largely made by individual effort and without any 

 general plan covering the whole area. It is probable that a' geologi- 

 cal survey of the Highlands would enable us to trace the limits of an 

 iron-bearing group, as has been indicated by the surveys of the New 

 Jersey Highlands.* 



Mines have been opened in Orange, Rockland, Westchester and 

 Putnam counties in this iron-ore district and from the New Jersey 

 line, at the south-west, to the Connecticut boundary on the east. Their 

 locations and names are shown on the map which accompanies this 

 report. Some of the largest and most productive mines in Orange 

 county have been worked more than a century, f This county was 

 famous for its iron manufacture during the Revolutionary war.J The 

 greatest development of the iron mines in Putnam county has been 

 since the opening of the Tilly Foster and Mahopac mines or during 

 the last twenty-five years. The distance from public lines of trans- 

 portation, the increased cost of working the smaller " veins " at 

 greater depths, the low prices for iron ore and the competition with 

 the richer ores of other parts of our country have necessitated the 

 suspension of work in some of the mines and led to the permanent 

 abandonment of those most unfavorably situated. Of the forty sepa- 

 rate mines, which have been ore producers, ten only were in operation 

 during a part or the whole of the year 1888. Their aggregate out- 

 put for that year amounted to 114,000 gross tons. The ores of the 

 Highlands district are the hard, crystalline magnetites. They are 

 generally rich, free from titanium, but contain a slight excess of 

 phosphorus above the limit for the manufacture of Bessemer iron, 

 excepting the Mahopac and Tilly Foster mines which have yielded 



* See "Ann. Report of the State Geologist for the year 1SS6." Trenton, 1887, pp. 

 82-S5. 



t Ore was discovered on the Sterling tract as early as 1750 ; the Forest of Dean 

 mine was opened about the same time. 



J See " History of the Manufacture of Iron in all ages," by James M. Swank, Phila- 

 delphia, 1S84, pp. 102-106. 



