rl64: NEW YORK STATE MUSEUM 



zontal series of joints divides the rock into " lifts " from 1 to 8 

 feet thick. 



Black powder is used in blasting, the holes being put in by 

 Ingersoll steam drills, three of which are in use. Three derricks 

 are in place at the quarry. By means of these the stone is lifted 

 to the ground level and run on little trucks down a tramway to 

 the dressing sheds. Little polished stone is sold, the greater 

 part of the product being patent hammered. 10 cut work is the 

 finest done; 6 cut is about the average finish. At present no 

 paving blocks are made up. 35 to 40 men are employed through 

 about 10 months of the year, in the quarry, dressing sheds and 

 loading. The quarry and dressing sheds are shown on pi. 53. 



From the dressing sheds the stone is transported by wagon 

 to the river where a derrick is used in unloading it from the 

 wagons and placing it on the scows. 



Among the buildings recently erected of stone from this 

 quarry are a church and a school building at Tarrytown, St 

 Joseph's church (Tremont av. and Washington st. New York), the 

 powder magazines at lona Island and the guardhouse at West 

 Point. 



Round island, Rockland co. A granite quarry (31a) operated by 

 Daniel E. Donovan on Bound island has furnished large quan- 

 tities of road metal. 



The chemical composition of this granite is shown by 

 analysis^ to be: 



/o 



Si02 63.19 



AI2O3 10.5 j 



FesOs 10.97 



Fe O I.5I 



Ca O 6.12 



MgO 1.44 



K2O 4.02 



NasO 1.92 



Pine Island, Orange co. Granite quarries have been operated 

 on Mt Adam (33), Mt Eve (34) and Pochuck mountain (32). 



^U. S. geol. sur. 20th an. rep't. Pt 6, continued, p. 421. 



