QUARRY MATERIALS OF NEW YORK I27 



The rock is uniform in color and grain, representing a good quality 

 of the Yonkers gneiss. The foliate texture is prominent and has 

 a north-south strike with a vertical dip. The joint structures in- 

 clude a horizontal set spaced about 8 feet, along which the stone is 

 quarried in benches. There are also north-south and east-west sets 

 spaced about 20 feet apart. On the north side of the quarry, the 

 east- west joints are more crowded, practically forming a heading, 

 and the rock in that section is adapted only for road material. 



The quarry is worked in a small way and the stone mostly sold 

 dressed as lintels, sills etc. Hand drills are used and the stone 

 broken out by black powder. The only mechanical equipment is 

 a horse derrick. Some good-sized blocks are quarried, the largest 

 measuring about 3 by 6 by 8 feet. The rock breaks quite smoothly 

 along the foliation. 



Russo quarry 



A small quarry has been opened in the last few years and recently 

 operated by John Russo. It. lies about 1000 feet south of the 

 Hackett quarry on Midland avenue, near Dunwoodie. The rock is 

 the same fine-grained bluish or pinkish gneiss, of foliate structure, 

 but is rather more broken than at the former quarry. The vertical 

 and horizontal joints are mostly spaced at intervals of 2 or 3 feet, 

 so that large-sized blocks are seldom quarried. The product is 

 building stone, employed locally in the construction of dwelling 

 houses. The scrap and inferior quality rock are sold for road 

 material. The work is all done by hand. 



A microscopic examination of the gneiss from this quarry shows 

 that there is considerable hornblende in addition to biotite, which 

 is the prevailing dark mineral. The feldspars and quartz are 

 partially granulated and the uncrushed remnant is drawn out along 

 the planes of foliation, the larger and smaller particles often occur- 

 ring in alternating bands. The rock is quite fresh, except for the 

 incipient alteration of the biotite. This has set free some iron which 

 as limonite forms a slight stain along the cracks and sutures. Zircon 

 and titanite are fairly abundant accessory minerals. The average 

 diameter of the quartz and feldspar particles is between .5 and 

 I mm, so that the texture is unusually fine. 



Beekman quarry 



The Beekman quarry is perhaps the oldest of the quarries in 

 the Yonkers gneiss. It was worked in the early part of the last 

 century and has been operative at intervals down to the present. 

 It is situated at Phillipse Manor, about a mile north of Tarrytown, 



