QUARRY MATERIALS OF NEW YORK 195 



whole. They are due to inclusions of quartz, mica, tremolite, 

 diopside and more rarely tourmaline. 



The building marbles are found in the more massive, heavily 

 bedded parts of the formations. They are predominantly white, 

 either a uniform brilliant white, or white clouded or banded with 

 blue. They are used both for exterior and interior work. Ex- 

 amples of their architectural employment may be seen in many 

 large structures in New York City, especially among the buildings 

 erected twenty or more years ago, as at that time the Westchester 

 county stone enjoyed greater favor among architects than any other 

 native marble. 



In durability, the dolomitic marbles from southeastern New York 

 show considerable variation, as has been remarked in the discussion 

 of weathering qualities. Some of the stone is ill-adapted to build- 

 ing purposes on account of the fact that certain phases show a 

 sugary, loosely bonded texture and decay rapidly when exposed to 

 the elements. It is unfortunate that such stone should ever have 

 been employed in buildings. On the other hand, the product of 

 many of the quarries has proved, under the rather trying conditions 

 of the eastern cities, to be an excellent architectural stone, equal in 

 weathering qualities to any of the other marbles in common use. 

 Rapid weathering apparently does not result from any peculiarities in 

 the composition of the stone, but depends upon a lack of coherence 

 and compactness whereby the mechanical influences of frost and 

 temperature changes are enabled to destroy the bond. Normally, 

 dolomite is harder and more resistent to the attack of solvents than 

 calcium limestones. 



DOVER PLAINS, DUTCHESS COUNTY 



Marble for building and ornamental purposes was once quarried 

 near Dover Plains. The ledges may be seen along the east side of 

 Tenmile creek southeast of the town. One of them is now the site 

 of an active quarry which is worked by the Dutchess County Lime 

 Co. for the manufacture of lime. The stone is a fine but rather 

 loosely grained dolomite, blue or white in color, and quite free of 

 silicates. The dolomite grains are round and not firmly welded, so 

 that they weather out readily when the stone is exposed to the 

 atmosphere. The beds in this section strike about N. io° E. and 

 stand on edge or are inclined to the east at an angle of 8o° to 85 °. 

 The color changes abruptly from white to blue across the strike, 

 apparently with the different beds. With its low percentage of 

 soluble matter (2 to 3 per cent), the stone is well adapted for 

 making magnesian lime. 



