THE MINING AND QUARRY INDUSTRY 



153 



able for over a mile on the strike occurs about 2 miles north of 

 Saratoga Springs on the line of the Adirondack railroad. 



The largest outcrop of trap rock in the State is that extending 

 along the west bank of the Hudson river, southward from Haver- 

 straw, constituting the remarkable scenic feature known as the 

 Palisades. This ridge crosses the Rockland county line into New 

 Jersey and continues as far as Bergen Point. The same rock 

 appears again on Staten Island but is not so well marked topo- 

 graphically. The rock is a dark, fine grained, crystalline aggregate 

 of plagioclase, augite and magnetite. It belongs to the diabases. 

 It is exceedingly hard and tough, and unlike most granitic rocks 

 shows little tendency to rifting and parting along planes of weak- 

 ness, so that it is admirably adapted for paving blocks and road 

 metal, of which the ability to withstand constant wear is an essen- 

 tial feature. A test of the trap from Rockland Lake made in the 

 laboratory for road material at Washington, D. C, gave the fol- 

 lowing results: coefficient of wear 13.2; per cent of wear 3; weight 

 in pounds a cubic foot, 192.5 ; pounds of water absorbed a cubic 

 foot, .3 ; cementing value, 80. Though the trap has been used to 

 some extent in buildings, it is too unyielding in the quarry to be 

 extensively employed for that purpose. 



The principal quarries are those at Rockland Lake, Haverstraw, 

 Upper Nyack and Mt Joy, Rockland county, and at Port Richmond, 

 Staten Island. Crushing plants are operated at all the quarries. 

 The product is used for road metal, concrete, railroad ballast, and 

 a small portion for paving blocks and building stone. 



Production of trap 



MATERIAL 



1904 



i9°S 



Cubic 

 yards 



Value 



Cubic 

 yards 



Value 



Crushed stone 



610 285 



$452 621 

 i5 875 



774 in 



$601 669 

 21 55o 





Total 





$468 496 





$623 219 









The production of trap rock in New York State in T905 was 

 valued at $623,219, as compared with $468,496, the value of the 

 output in 1904. Of the totals given. $601,669 in 1905 and $452,621 

 in 1904 represented the value of crushed stone and $21,550 and 



