88 NEW YORK STATE MUSEUM 



" rock ore," that which is sorted by hand, and " wash ore," the 

 residue obtained after removing the clay and sand by washing. It 

 carries from 40 to 50 per cent iron and less than i per cent phos- 

 phorus. Among the prominent mines that have been active within 

 recent years may be mentioned the Sylvan lake group, the Beekman, 

 Pawling, Clove and Dover mines in Dutchess county and the Man- 

 hattan, Weed and Copake mines in Columbia county. The Amenia 

 mine at Amenia, Dutchess co. is the only one now operated. 



In the western part of Columbia county, a short distance from the 

 Hudson river, there is a small district that has produced carbonate 

 ores. The ore bodies lie along the western slope of a range of hills 

 at an elevation of 300 or 400 feet above the river. They are in- 

 cluded between slates and sandstones of the Hudson river series and 

 show many points of similarity to the limonite deposits above de- 

 scribed. The Burden mines are the largest in the district. They 

 were worked between the years 1875 ^^<i 1901. The ore is a gray 

 compact siderite containing some calcite, quartz and pyrite. Though 

 low grade, the average tenor can be raised by roasting to about 50 

 per cent iron. The greater part of the ore is of Bessemer quality. 



6 Limonite ores occur within the serpentine area of Staten Island 

 and at one time were quite extensively mined. The serpentine 

 underlies the broad ridge extending from St George on the north 

 shore to Richmond near the center of the island. It is undoubtedly 

 a metamorphosed basic intrusive allied to the peridotite class of 

 rocks. The ore lies in superficial depressions directly upon the 

 serpentine and is generally covered by glacial drift. It carries from 

 38 to 55 per cent iron. A small percentage of chromium is shown 

 in the published analyses ; its presence may be ascribed to leaching 

 of the serpentine which contains chromite and is probably also the 

 source of the iron. The principal openings are the New Dorp, 

 Tower, Cooper & Hewitt and Tyson mines. 



Notes on mining developments 



Mineville. This well known district holds the leading place 

 among the producers of iron ore in the State. The deposits are of 

 unusual size, affording the basis for large scale operations with their 

 consequent economies, and are also above the average in richness. 

 They are worked by Witherbee, Sherman & Co. and the Port Henry 

 Iron Ore Co. 



The mines now active comprise " 21," Bonanza and Joker of the 

 Old Bed group and the Harmony and Smith mines. Mine "21 " 



