832 NEW YORK STATE MUSEUM 



This does not qnite agree with an analysis made by the writer, 

 which represents an average of the quarry as follows: 



Lime carbonate 59 . 84 



Magnesium carbonate 36.8 



Alumina .4 



Ferric oxid , .25 



Silica > 2 . 31 



99.6 



A small quarry was once in operation near Scarsdale, but the 

 rock contains considerable mineral impurities. ■ 



Crystalline limestone extends up the valley of Annsville cove 

 and Sprout brook for several miles, and is exposed at a number 

 of places, specially along the line of the narrow gage railroad 

 leading up to the Edison magnetite mines. The best exposure of 

 this is in the quarry If miles west of Peekskill rock. The rock 

 is a fine grained, grayish white stone, which seems to be the 

 better quality toward the eastern end of the mine, where it is of 

 a darker color. The working face exposed is over Y5 feet long. 

 The following analysis made by J. D. Irving shows the composi- 

 tion of the stone, and illustrates the point that far less magnesia 

 exists in this limestone than is found in other portions of West- 

 chester county. 



Silica 2.5 



Ferric oxid and alumina 1.55 



Lime carbonate 81 . 64 



Magnesium carbonate , , , 13.5 



99.19 



Other exposures of this same rock outcrop, as low ledges on 



the property of Mr Higgins about 2|- miles from Peekskill village. 



« 



Some of these ledges show a stone of considerable purity, while 

 in others the rock is rather micaceous. 



