86 



NEW YORK STATE MUSEUM 



The ores are crystalline magnetites, rich and free from titanium, but 

 generally containing too much phosphorus to pass as Bessemer 

 grade. Alining has been carried on intermittently for 150 years. 

 The Sterling mine near Warwick and the Forest of Dean mine near 

 Fort Montgomery are among the more important mines in Orange 

 county. They have been inactive for several years. The Tilly 

 Foster and Mahopac mines of Putnam county have yielded Bessemer 

 ores. The former was' of unusual size, the ore body measuring 

 1500 feet long and 160 feet wide at the middle. 



3 This district is confined to a narrow belt running northeasterly 

 from Philadelphia, Jefferson co., to Rossie, St Lawrence co.. a dis- 

 tance of 30 miles. In this section the Adirondack gneisses and 

 crystalline limestones continue as far as the St Lawrence river, 

 though there are intervals where they are concealed by the Paleo- 

 zoic formations. The hematite deposits lie below the Potsdam 

 and are associated with an altered rock locally called serpentine. 

 C. H. Smyth jr. 1 who has described very fully the relations of the 

 ore bodies, has explained the serpentine as a product of alteration 

 of the surrounding granite and gneisses. The ore bodies are irregu- 

 lar and inclose knobs and masses of the wall rock which sometimes 

 cut off the ore entirely. They appear to occupy an approximately 

 definite horizon in the gneiss series parallel to a stratum of pyritous 

 schist. The ore is an earthy massive hematite of deep red color. 

 Cellular and stalactitic varieties occur, and in some deposits there 

 is much specular ore. It runs from 40 to 50 per cent iron with 

 phosphorus in excess of the Bessemer allowance. The Old Sterling 

 mine, near Antwerp, and the Caledonia and Kearney mines near 

 Spragueville have been very productive. 



4 The Clinton formation outcrops as a narrow but persistent 

 band extending over 200 miles from the Niagara river east to Her- 

 kimer county. It is composed mainly of green shales and limestones 

 with one or more beds of hematite. The latter does not appear in 

 the extreme western section, being first encountered in Monroe 

 county. At the Rochester gorge of the Genesee river there is a 

 single bed 14 inches thick, underlain by 23 feet of green shale. The 

 overlying beds include 14 feet of limestone, 24 feet of green shale 

 and 18 feet of limestone at the top. At Ontario, Wayne co., the 

 ore is found beneath 20 feet of shale and earth and has a thickness 

 of 22 inches. The existence of more than one bed at this point has 

 not been established. Farther east in Cayuga county near Sterling 

 two beds, aggregating 36 inches, have been mined. Recent explora- 



1 N. Y. State Mus. 47th An. Kep't. 1894. p. 087. 



