MARBLE. 69 



remains, which give it a variegated and beautiful appearance. It also frequently presents, on 

 fracture, that singular columnar structure, at right angles to the layers, which has been quite 

 aptly compared by Mr. Vanuxem to the sutures of the skull. In consequence of a suggestion 

 made by that gentleman,* that the appearance in question was owing to sulphate of magnesia, 

 I subjected a specimen to analysis, and found its composition to be as follows, viz : 



Carbonate of lime, 75. 65 



Carbonate of magnesia, 20.70 



Silica and alumina, . 2.25 



Oxide of iron, 0.35 



Moisture and loss, 1.05t 



Oneida County. In this county we have the Trenton limestones, which will furnish beau- 

 tiful black marbles ; and the grey marble near the Holland patent, and on a branch of Steuben 

 creek. 



Onondaga County. In this and the adjoining county (Madison), t!ie grey crinoidal lime- 

 stone affords a marble scarcely excelled by any in the country for beauty, durability, and the 

 fine polish which it receives. The quarries in Onondaga county are moreover very extensive, 

 and yield blocks of great size. The marble is not only used for ornamental purposes, but in 

 its dressed state is employed in the construction of locks, aqueducts, and other similar struc- 

 tures. The public works recently constructed in the vicinity of Syracuse present a striking 

 proof of the superiority of this material over that formerly used for similar purposes, while at 

 the same time they offer a no less striking illustration of the great advances which have been 

 made in the arts of construction in this State. 



I have analyzed two specimens of the grey crinoidal limestone, the one from the quarry near 

 the Chittenango falls in Madison county ; the other from the Split Rock quarry in Onondaga 

 county. The following are the results — No. I. is from the former, No. II. from the latter : 



I. II. 



Carbonate of lime, 98.50 99.30- . 



Oxide of iron, 0.35 0.20 



Insoluble matters (silica and alumina), . 0.90 0.40 



 New-York Geological Reports, 1838. 



1 1 have also analyzed a specimen of limestone from the bed of the river at Rochester, Monroe county, called " Calciferous 

 Slate" by Prof. Eaton, and "Caleareous Shale" by Mr. Hall. It is bluish grey, a little crystalline, and emits a strong bituminous 

 odour when struck or subjected to heat. Its composition is, 



Carbonate of lime, 44.65 



Carbonate of magnesia, .- 30.00 



Silica, with a little alumina 24.00 



Oxide of iron — 1.00 



 f Bituminous matter, 0.30 



Thii" bituminous matter occurs in many of the limestones which I have examined. It is found in the residunm unacted on by 

 acids, and, when subjected to heat, gives out an odour resembling that of burning peat. 



