THE MINING AND QUARRY INDUSTRY 



&5 



of the wall rock. In the northern districts of Clinton and Franklin 

 counties they take the form of sheets and elongated lenses inclined 

 at a high angle, and with some exceptions are quite free from 

 irregularities due to folding or other dynamic influences. Con- 

 spicuous examples are the great ore zone at Lyon Mountain extend- 

 ing several miles along the strike, the similar but smaller deposits 

 of Palmer hill and the succession of lenticular bodies of Arnold hill. 

 The magnetite may occur as disseminated particles associated with 

 the minerals of the gneiss, as at the first mentioned locality, con- 

 stituting a lean ore which requires concentration before it can be 

 used commercially. Again there are deposits of nearly pure mag- 

 netite. The lean ores as a rule contain less apatite and thus have 

 some advantage over the rich but phosphoric ores. 



In the southeastern Adirondacks there are a great number of mag- 

 netite deposits of varying size and character. While the prevailing 

 type is lenticular the form has been greatly modified by the exten- 

 sive faulting and folding that have taken place. This is particularly 

 true of the Mineville and Hammondvillc districts in Essex county 

 where the ore bodies exhibit great irregularities. At Mineville 

 occur some of the largest deposits of high grade magnetite in the 

 country. 



On the northwestern side of the Adirondacks magnetite ores are 

 not so widely distributed. The Benson, Jayville and Clifton deposits 

 in St Lawrence county, however, are known to be extensive. At 

 Benson the ore contains much quartz and feldspar and resembles 

 the disseminated magnetites of Clinton county. 



The titaniferous magnetite deposits are distinguished from those 

 just described by their association with clearly igneous rocks of 

 basic composition. They undoubtedly represent segregations from 

 the surrounding rock mass while it was in a fused condition. Every 

 gradation from normal rock to pure magnetite can be found. The 

 deposits are developed in western Essex county at Lake Sanford 

 and in the towns of Elizabcthtown and Westport, not far from Lake 

 Champlain. 



2 The Precambric gneisses which enter the southeastern part of 

 the State from New Jersey forming the ridges known as the High- 

 lands of the Hudson, contain magnetite deposits somewhat similar 

 to those in the Adirondacks. About 40 mines have been operated 

 in the region in Orange, Putnam, Rockland an' /Vestchester coun- 

 ties. The Oie bodies have a northeasterly trend, conforming to the 

 gneiss, and usually show a pitch across the dip. They vary in shape 

 from lenticular masses to thin sheets, while some are very irregular. 



