2l6 BULLETIN OF THE NEW YORK STATE MUSEUM 



the loosely aggregated stone the grains are readily torn apart, 

 and the mass falls with a blow, — a heap of sand. Generally 

 the more siliceous the stone and the cement, the greater the 

 degree of hardness and strength. The size, color and ar- 

 rangement of the component grains are the elements which 

 affect the appearance and give beauty to the sandstone. 

 The durability is connected intimately with the physical 

 constitution and the chemical composition. As a rule 

 calcareous and clayey cementing materials are not as 

 enduring as the siliceous and ferruginous. The stone best 

 resisting the action of the atmospheric agencies is that 

 in which the quartz is cemented by a siliceous paste, or 

 in which the close-grained mass approaches in texture a 

 quartzite. 



The presence of minerals liable to decomposition, as 

 feldspar, highly kaollnlzed, of mica, marcasite, and pyrlte, of 

 calcite in quantity, and clays, affects the durability and tends 

 to Its destruction. 



Sandstones are classified according to their geological age 

 also. They are found occurring in all the series, from the 

 oldest to the most recent formations. And those of a given 

 age are generally marked by characteristic properties, which 

 serve for their Identification, aside from the fossil organic 

 remains by which their exact position in the geological series 

 is fixed. This persistence In characters Is exemplified in the 

 Medina sandstones of the state, in the blue-stone of the 

 Hudson river valley, and in those of the Triassic age or 

 new red sandstone. 



Sandstones are found occurring in workable quantity In 

 all the greater divisions of the state, excepting the Adiron- 

 dack region, and Long Island and Staten Island.'^ 



Quarries have not however been opened everywhere in 

 the sandstone formations, because of the abundant sup- 

 plies of superior stone from favorably situated localities. 



* There are isolated outcrops of brown sandstone and ferruginous conglomerate on 

 Long Island, but not of any considerable extent or importance. 



