n ECONOMICAL MINERALOGY. 



The marbles of Sing-Sing, and almost all the others of this county, belong to the variety 

 called dolomite. I made an analysis of a specimen from the vicinity of the State Prison. It 

 consisted of small grains, feebly cohering ; had a white colour, with a few dark spots. The 

 results were the following : 



Carbonate of lime, 53. 24 



Carbonate of magnesia, 45.89 



Silica and alumina, with a trace of oxide of iron, . . . 87 



Quite similar to the beds just described, are those which occur in the vicinity of Hastings 

 and elsewhere in the northern part of this county ; and the same remarks will apply generally 

 to the quarries at West-Farms and in Eastchester. The marble from the Eastchester quar- 

 ries is perhaps more highly esteemed than any in the county. It is white and bluish white, 

 coarse grained, and susceptible of a medium polish. It is less friable, and usually more free 

 from foreign minerals, than that obtained at Sing-Sing. Blocks of large size and of uniform 

 texture are quarried here, the strata being frequently several feet thick. Mr. Mather states, 

 that at the time of his yisit in 1838, they were quarrying a block 150 feet long, eight feet 

 thick, and seven feet broad, and which it was thought would be worth $20,000. The marble 

 obtained at these quarries is transported five or six miles by land carriage, and then shipped 

 to New- York and elsewhere. The Custom House at New- York was built of this material. 



A specimen of this marble, from Kane's quarry in Eastchester, was found to contain 



Carbonate of lime, -... 61.75 



Carbonate of magnesia, 38.25 



The white limestone of this county, in addition to its employment as a marble, is also 

 largely used for burning into lime, and this not only for home consumption, but also for ex- 

 port. At the Cold Spring furnace, it is used as a flux for the reduction of iron ore. 



Besides the white dolomitic marbles already described, there occurs in the vicinity of New- 

 Rochelle, Rye and elsewhere, serpentine in vast beds, which presents beautiful shades of 

 colour, and in small specimens takes a high polish. Unfortunately, however, it is so mixed 

 with carbonate of magnesia, asbestus and other foreign minerals, as to render it unfit to be 

 worked as a marble. Thus a block from the vicinity of New-Rochelle, concerning which 

 high expectations had been raised, was found to have running through it in every direction 



selected for the purpose, such as the Capitol and the President's House at Washington, the Bank of the United States, the Mint 

 and other public buildings at Philadelphia, the Monument erected to the memory of Washington at Baltimore, have certainly a 

 most imposing and gorgeous appearance, owing to the fineness and beauty of the material. But the buildings which are constructed 

 of the blue or unselectcd marble, such, for example, as the State Capitol at Albany, (the new State Hall,) have a bloated and 

 dingy look ; and the general effect produced by the marbles in these buildings is greatly inferior to that of some of the sandstones 

 from Craigleith and other British quarries." Edinhirgk New Pkitosophicaljoumai, April, 1841. 



The " dingy" appearance here spoken of, and which is particularly observable in the State Hall in damp or rainy weather, is 

 owing to the want of care in the selection of the blocks, most of them being of a bluish tint, while others are white. Whatever 

 difference of opinion there may be in regard to the relative beauty of different coloured marbles, uniformity should if possible be 

 preserved. It is the want of this, rather than the colour, that injures the general effect of the building in question. ' 



