QUARRY MATERIALS OF NEW YORK 203 



MgO 21.25 20.71 20.77 



MgCOs 43.62 



CaO 30.16 j:: 30.63 



CaCOs 54.69 



CO2 47.3 46.66 



Insol 1.33 ,91 



99-35 99-59 



Analysis no. i is by W. F, Hillebrand ; no. 2 by P. deP. Ricketts ; 

 no. 3 by F. A. Wilber. 



NONMETAMORPHIC MARBLES 

 Several kinds of unmetamorphosed limestones that occur in the 

 State have been used for ornamental stones and may be included 

 with the marbles for purposes of description. 



GLENS FALLS 



The Paleozoic limestones at Glens Falls, which are exposed in 

 cliffs on both sides of the Hudson river, contain at their base a 

 thick-bedded, fine-grained black limestone of Black River age. 

 The layer is about 12 feet thick. The overlying limestones and 

 shaly layers belong to the lowermost Trenton beds and are known as 

 the Glens Falls limestone. The thicker and finer limestones are 

 quarried for lime, building stone and other purposes, while the 

 black layer yields also a good black marble. When polished, the 

 latter shows a dense uniform black surface, scarcely distinguishable 

 in appearance from the best of the imported black marbles. It is 

 hard and very fine in grain. Large quantities were quarried and 

 cut at one time, but the demand has fallen off in recent years. The 

 stone was used largely for floor tiling, for which it was well 

 adapted on account of its good wearing qualities and permanency 

 of color. It has been made also into mantels, wainscoting, table 

 tops and other interior decorative work. The principal shipper of 

 late years has been Finch, Pruyn Si Co. who use the materials also 

 for lime and crushed stone. Smock states that the black marble 

 has a specific gravity of 2.718 and weighs 169.4 pounds to the cubic 

 foot. G. P. Merrill gives crushing tests on limestone from Glens 

 Falls which may refer to the black layer, although not so stated. 

 The strength on the bed was 11,475 pounds and on the edge 10,750 

 pounds to the square inch. 



WILLSBORO POINT, ESSEX COUNTY 



A fine black limestone is found in the Chazy beds which underlie 

 the long neck of land that projects into Lake Champlain from the 



