QUARRY MATERIALS OF XEW YORK l8l 



Gouverneur stone some signs of decay and disintegration, par- 

 ticularly on the tops, are noticeable, and small pieces can be chipped 

 off with a knife blade. The durability of the stone for building 

 purposes has been tested in some of the older structures in Gouver- 

 neur. 



PHYSICAL PROPERTIES 



Marble is heavier than granite and has a specific gravity ranging 

 from about 2.70 in the case of. calcite varieties to 2.88 for dolomites. 

 These figures correspond to weights for each cubic foot of from 

 168 to 180 pounds. The South Dover white marble, a nearly 

 pure dolomite, has a specific gravity of 2.86 and a weight of 178.5 

 pounds ; the Gouverneur slightly magnesian blue marble possesses a 

 specific gravity of 2.74 and a weight of 171 pounds for each 

 cubic foot. 



The compressive strength of marble varies within rather wide 

 limits according to the textural features. Merrill ^ credits the 

 Pleasantville coarse dolomite with the very high crushing strength 

 of 22,383 pounds a square inch. The Tuckahoe marble, according 

 to the same authority, gave a test of 13,076 pounds. Both figures 

 refer to the strength when tested across the bed. Three samples 

 of marble from the quarries of the South Dover Mai^ble Co. showed 

 a minimum compressive strength of 17,401 pounds and a maximum 

 of 20,882 pounds.^ These results compare well with those obtained 

 from the best building marbles of other districts. 



The Gouverneur marble, represented by a sample from the quar- 

 ries of the St Lawrence Marble Co., showed a strength under 

 compression of 12,692 pounds a square inch.^ 



Tests of transverse and tensile strength are rarely made, though 

 they afford useful data in estimating the coherence and durability 

 of marble. 



GEOLOGY OF THE NEW YORK MARBLES 



The metamorphic phanerocrystalline limestones, which include all 

 marbles in the true sense, as already explained, occur only in regions 

 where the rock formations have been squeezed, folded and up- 

 raised into mountains. Originally they were horizontally bedded, 

 common limestones accumulated on the floors of the ancient seas 

 by the slow aggregation of the shells of organisms that lived in 

 these waters and in part perhaps by direct chemical precipitation 



i 



1 Stones for Building and Decoration. New York, 1897, p. 461. 



2 Twentieth Annual Rep't U. S. Geol. Survey, pt 6, cont'd. 1899, p. 422. 



3 Op. cit., p. 423. 



