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NEW YORK STATE MUSEUM 



year to year. The figures for building- sand and gravel, doubtless, 

 understate the actual business, falling short perhaps as much as 15 

 per cent of the total output in any one year. The operations are so 

 widely scattered and often of so fugitive nature that it is not pos- 

 sible to keep informed of all developments as they take place. 



Production of sand and gravel 



MATERIAL 



Building sand .... 



Molding sand 



Fire and core sand 



Other sand 



Gravel 



Total 



1913 



102 688 



449 224 



38 57i 



75 000 



918 783 



52 584 266 



1914 



151 521 



310 727 



23 944 



75 000 



650 895 



52 212 087 



1915 



185 812 



415 073 



24 797 



75 000 



965 336 



$2 666 018 



Building sand and gravel. Building sand is employed in lime 

 and cement mortars, for concrete, artificial stone, etc. It is de- 

 sirable that sand for this use should be mainly composed of quartz 

 which is the strongest and most durable of the minerals that occur 

 in sands, but ordinarily the sands supplied consist of quartz mixed 

 with considerable percentages of silicate minerals, especially feld- 

 spar, mica and hornblende. Silt and clayey matter are also present 

 in most sands, especially those of glacial or stream origin. 



For small structures where little stress is laid upon the elements 

 of strength and permanency the silty mixed sands, if not too in- 

 ferior in quality, may serve well enough, as in fact large quantities 

 of such material are thus utilized with satisfactory results. It is 

 also true that the tendency in building construction is toward a 

 closer scrutiny and control of all the materials, inclusive of the 

 sand and coarser aggregates. The strength of mortar and concrete 

 is dependent quite as certainly upon the character of the sand as 

 upon that of any other constituent, and in important works like 

 highways, bridges and large buildings it is the practice now to 

 require certain standards of texture and composition. Hence there 

 has arisen an increased demand for the better grades which is 

 serving to stabilize and centralize the industry. The requirements 

 are such that the supplies are obtainable only from certain re- 

 stricted areas or through artificial benefication of low-grade sands 

 by washing and sizing. 



