No. 50.] 
89 
springs, are remarkable for the evolution of nitrogen gas, which is con- 
stantly going on. 
There are in Rensselaer county several localities of crystallized 
quartz, occurring in fissures in the rock. One of these is at Lansing- 
burgh, and was formerly knov^^n by the name of Diamond Rock. But 
it has long since been shorn of its beauty. This mineral, (quartz,) in 
the form of basanite and jasper, are also occasionally met w^ith. Infe- 
rior specimens of calcareous spar, and thin seams of anthracite are to 
be noticed as among the minerals of this county. Iron pyrites is abun- 
dantly diffused and as usual gives rise by its decomposition, to the 
formation of the sulphates of iron and magnesia. To the preceding 
list are only to be added slaty chorite and oxide of manganese, which 
are occasionally found, together with loose masses of hematitic iron. 
RICHMOND COUNTY. 
This county is exceedingly interesting to the mineralogist, not so 
much on account of the variety of minerajs that are found in it, but of 
the manner in which they are associated and pass into one another. 
Indeed, the remarks which were made under Putnam county are gene- 
rally applicable here. A fine illustration of this grouping of minerals 
may be observed very near the quarantine. At this locality, which is 
on the road side, a short distance from the old pavilion, will be found 
a serpentine rock, embracing veins of asbestus, assuming every variety 
from the compact and ligniform to the amianthoid, depending in a great 
measure upon the exposure to which it has been subjected. We obtain- 
ed specimens of the fibrous kind a foot or more in length. A little 
further on we find masses of precious serpentine, with veins of the 
marmolite of Mr. Nuttall, but which, although differing somewhat from 
serpentine in its external characters, is closely allied to, if not identical 
with, it. Then we have the magnesian marble of Nuttall, or the white 
compact carbonate of lime and magnesia, with a conchoidal fracture, 
and a hardness that sometimes causes it to strike fire with steel. This 
upon analysis proves to be identical with the gurhofite, noticed among 
the minerals of Putnam county. And with these again are associated 
some varieties of talc, and more rarely the hydrate and carbonate of 
magnesia, and the chromate of iron. There are many intermediate or 
transition states, of these minerals, which in hand specimens might pass 
for distinct ones, but an attentive examination of the locality, will show 
their true charactcis and save the chemist much labor and anxiety. 
[Assembly No. 50.] 12 
