S30 NEW YOEK STATE MUSEUM 



There are certain layers on the west side of the quarry which 

 should be avoided, as they run more silicions. In structure these 

 layers are thinner than those of the purer stone and more finely 

 <crystalline. Their composition was found to be as follows : 



Silica , 6 . Y5 



Ferric oxid 1.08 



Alumina 3 . 02 



Lime 28 . 32 



Magnesia 17.94 



The best quality of stone makes a very white lump lime. 



The quarries at Tuckahoe, Westchester co., are most exten- 

 sive and are all located in the same stratum, which extends north- 

 east and southwest and has a thickness of about 40 feet. The 

 firms operating the quarries are O'Connell & Hillery, ^N'orcross 

 Bros, and the Tuckahoe marble co., also known as J. Sinclair Co. 

 The rock in all of these quarries is a magnesian limestone of 

 granular character and moderately hard. Its character is quite 

 constant. The beds dip steeply to the west, and those forming 

 the walls of the quarry are very micaceous. 



O'Connell & Hillery's (pi. T4) is the most southern quarry and 

 is but a short distance from the Tuckahoe railroad station. The 

 rock is used chiefiy for making lime, but in recent years the manu- 

 facture of marble dust has also begun. The following analysis 

 of the stone was furnished by the company. 



Carbonate of lime 70 . 1 



Carbonate of magnesia 25.4 



Insoluble matter 2.4 



97.9 



Two analyses have been given of the stone, ^o. 1 was made by 

 Prof. P. de P. Ricketts, and no. 2 by W. T. Hillebrand. 



1 2 



Insoluble 1.33 



Lime < 30.16 30 . 68 



