No. 275.J 
19 
the quarries from which these are obtained. I shall only add a few re» 
marks concerning the mineralogical and chemical characters of the Sing- 
Sing marble, though I believe they are also generally applicable to all 
the marbles in this county. 
24. The Sing-Sing marble is granular, and sometimes so friable that 
it can be crushed between the fingers. This tendency to disintegration 
is very manifest in those parts of the strata which lie near the surface 
of the ground, and have the appearance of beds of sand. This mar- 
ble, moreover, frequently contains masses of tremolite, quartz, and 
grains or crystals of iron pyrites, the two former rendering it sometimes 
difficult to be worked, and the latter, by its decomposition, causing red- 
dish stains, which detract from the beauty of the material. It is, how- 
ever, found to improve with the extent of the excavations, becoming 
more compact in its texture, and more free from these foreign minerals. 
The ease with which this marble can be worked, its good colour, and 
perhaps more than all, the facility with which it can be transported, will 
undoubtedly secure for it extensive use as a building material. The 
State being largely interested in these quarries, it is manifestly for its 
interest that the working of them should be conducted in the most ju- 
dicious, as well as economical manner. By which I mean, that any rea- 
sonable outlay should be incurred, if by this means a finer and more du- 
rable kind of marble can be thus rendered accessible. 
The marbles of Sing-Sing and Kingsbridge belong to the variety called 
Dolomite, which is characterized chemically by its containing a certain 
portion of carbonate of magnesia in combination with the carbonate of 
lime. I made a careful analysis of a specimen from Sing-Sing. It con- 
sisted of minute grains, was very friable, of a white colour, with a few 
dark spots. The composition was found to be as follows: 
Silica, alumina, (with a trace of iron,) 0.87 
Carbonate of lime, 53.24 
Carbonate of magnesia, , . . , 45 .89 
100.00 
The lime afforded by the burning of dolomite is thought not to be 
generally applicable to the purposes of agriculture, in consequence of 
the magnesia which it contains. It is, however, well adapted to most 
building purposes, and if the views, recently suggested by Vicat are 
correct, it is not improbable that it may be found of great value as a 
