212 
j Assembly 
To return to the clays of Warren county. I would suggest the pos- 
sibility of employing those which are coloured, (and which, on this ac- 
count, are unfit for porcelain,) in the manufacture of pipes and the 
coarser kinds of pottery, where colour is not a matter of much conse- 
quence. They would form excellent crucibles and pots, and if mixed 
with the proper proportion of feldspar, an excellent glazing or enamel 
for the ordinary earthen wares. The clays of New-York are mostly 
calcareous, and hence fusible and ill adapted for any kind of ware which 
requires a high temperature in baking or burning. These clays, then, 
are of great importance, and may justly be considered as a great acces- 
sion to the mineral riches of the State. 
Marble, 
Marble of different kinds and qualities is abundant in the Second 
Geological District. Some of the varieties have been noticed in the 
preceding reports. Many of the localities are favorably located, both 
as to water power for sawing, and for safe transport to market. The 
only variety of marble now wrought belongs to the Trenton limestone, 
or blue limestone as it is called. This is usually dark, varying from a 
dark gray to a jet black. The dark colours have generally obtained the 
preference in market for mantel pieces and ornamental work. 
One of the most valuable quarries which has been opened is at Glen's 
Falls. Nature at this place has exposed the strata in such a way that 
the whole thickness of the limestone can be examined without the 
labor of artificial or expensive mining. The river has cut into the rock 
to the depth of at least 70 feet. 
The marble is extensively manufactured by two enterprising compa- 
nies; it is therefore favorably known to the public, and has acquired a 
high reputation. For this reason it would be superfluous for me to 
give a particular account of its qualities. I take the liberty, however, 
to subjoin a letter which I have recently received from the agent of the 
Glen's-Falls company in relation to the position of the marble in the 
quarry, and also of the quantity which has been manufactued, &c. 
" The Hudson river at Glen's-Falls has worn a passage through the 
limerock to a vast depth, rising in some places seventy feet from its sur- 
face. The strata measure from one inch to ten feet. A short distance from 
the river, on the Saratoga side, lying on limestone, is found black slate. 
Succeeding this are found strata of marble; slabs have been sawed and 
used for fire-places. It is sound, and of good colour. Succeeding this 
on both sides of the river, are found 50 strata of limestone, composed 
