MINERAL RESOURCES OF THE STATE OF NEW YORK 1^7 



The ore bodies occur as seams following the schistosity of the 

 gneiss and as irregular impregnations of the latter. They are appar- 

 ently replacements of the country rocks formed by invading 

 ferruginous solutions. Fm3^th connects the source of the iron with 

 the pyrite which appears very probably from the close association 

 and the further fact that the hematite was deposited at a much 

 later period, probably largely in Postcambrian time, since the 

 Potsdam in contact with the ore is itself heavily impregnated and 

 altered so as to be difficultly distinguished from the normal ore. 



The occurrences are individually quite widely distributed and 

 there are a large number of mines and prospects within the area 

 covered by the towns of Antwerp and Theresa, Jefferson county, 

 and Gouverneur, Rossie, Hammond, Macomb, Fowler, Edwards, 

 Hermon, De Kalb and Canton, St Lawrence county. Most of them 

 may be grouped in a few belts that have the same boundaries as the 

 pyrite belts. The more important occurrences from a mining stand- 

 point are found in the gneiss belt which extends from the town of 

 Philadelphia on the southwest into and across southern St Lawrence 

 county and includes the Antwerp-Keene deposits which have been 

 most extensively exploited. 



The hematites assay upward of 40 per cent iron, the richest 

 averaging 55 to 58 per cent, and a variable phosphorus content, too 

 high for Bessemer ore. The main drawback seems to be a rather 

 high percentage of silica, arising from unreplaced quartz and silicates 

 of the gneiss and their alteration products. The total product has 

 been about 2,500,000 tons. Mining was in progress from about 

 1825 to 1910. In the early years the ore was smelted locally in 

 charcoal furnaces, but during the last 30 years or so it was shipped 

 mainly to Pennsylvania. 



Little systematic exploration has been attempted in this section; 

 in fact there is less known about the resources than of any other 

 iron ore district in the State. Most of the deposits, so far opened, 

 were exposed at the surface or showed indications of their presence 

 by the character of the soil which usually takes on a deep iron stain 

 wherever in contact with the hematite below. The cover of drift on 

 the uplands is thin, a few feet of sand and gravel with some bowlder 

 clay constituting the glacial deposit in most places. There is no 

 doubt that deposits are concealed under the Potsdam strata, through 

 which the iron is not readily revealed, and others may lie under 

 drift -filled valleys in which the glacial accumulation may have a 

 thickness of 100 feet or more. A guide to exploration is to be found 

 in the occurrence of pyrite which accompanies the hematite belts 

 throughout their extent. In the Antwerp-Keene belt there seems 



