82 NEW YORK STATE MUSEUM 



ECONOMIC AND ENGINEERING GEOLOGY 

 Mineral resources 



A region of such variety of rock type would lead one to expect 

 that the mineral and structural material resources of the district 

 might be very promising indeed. This is all the more expectable 

 when one takes into account the complicated igneous and meta- 

 morphic history which might readily have produced important 

 mineraHzing effects. It is somewhat surprising, therefore, to find 

 that mineral resource development has been very limited. At numer- 

 ous places quarries have been opened and rock for structural pur- 

 poses has been produced. At a few places economic minerals, such 

 as pyrite and iron ore, have been worked in former times. Sands 

 and gravels have been produced as well as road metal, lime and clay. 

 More recently, investigations have emphasized the presence of 

 material for crushed rock, high-grade silica, water and other things. 

 These will be taken up briefly. 



Building stone. Large amounts of stone suitable for structural 

 use are available. The chief items are granite, quartzite, limestone, 

 marble, and gneiss. 



Granite. A very excellent and unusually attractive granite has 

 been quarried 2 or 3 miles east of Peekskill at two places, both in 

 the younger granite formation, known in this paper as the Peeks- 

 kill-Mohegan granite. A very light-colored, almost white granite 

 was quarried in a portion of the area nearest to Peekskill usually 

 known as the Peekskill granite quarry. This quarry furnished stone 

 for the New Croton dam, and although it is very suitable for build- 

 ing purposes and because of its fine color, would be a strong com- 

 petitor in the New York City market, the quarry is not now worked. 

 This is in large part because of troublesome jointing conditions. 

 There is nothing against the quality of the stone and it is possible 

 that at some other point work could be established where excessive 

 jointing would not interfere. 



It is an interesting bit of history with regard to this quarry that 

 suit was brought against the operators, who worked it for the 

 supplies used in Croton dam, for ruining the quarry, the claim being 

 made that the jointing condition now seen in it was largely pro- 

 duced by extravagant and careless use of explosives in quarrying, 

 Although it is true that the use to which the material was to be 

 put, made it possible to utilize much rough broken rock and that 

 on this account very careful handling was not so necessary as for 



