No. 50.] 
51 
In the southern part of the State, and especially in the county of 
Putnam, there occur beds of serpentine of great extent. They appear 
to flank the primitive ridges, and are associated with the minerals which 
usually accompany this rock. In many places the serpentine is com- 
pact, susceptible of a good polish, and will undoubtedly be at some 
future time much used as an ornamental marble. 
A fact of some importance was noticed in the examination of these 
beds of serpentine, and it is that the soil in their vicinity seems not to 
have been injuriously affected by that substance. When it is recollect- 
ed that serpentine contains a large proportion of magnesia, this fact 
may throw some light upon the question whether that earth can be ad- 
vantageously employed as a manure. On this subject I have only time 
to add that magnesia in the form of a carbonate, is an abundant consti- 
tuent of many of the rocks in the western part of the State, and must 
have formed a part of the soils which originally covered them. I have 
found it in the proportion of from 20 to 30 per cent, in the limestone of 
Rochester and Lockport, in the calciferous slate of Chittenango, and 
in all the water limestones that I have yet examined. Now the soils 
in the immediate vicinity of these magnesian rocks are among the most 
fertile in the State, 
In the counties of Jefferson and St. Lawrence, the beds of serpentine 
are often replaced by the so called Renssellaerite, which is probably 
nothing more than a mixture of soapstone and pyroxene, sometimes as- 
suming the crystalline form of the latter mineral, and at others being 
compact and susceptible of a fine polish like serpentine.* This 
substance, principally on account of its softness and the ease with 
which it may be reduced to powder, has been been mistaken for gyp- 
sum and used as a fertilizer. But it need hardly be said that if the above 
view of its composition be correct, and if we know any thing concern- 
ing the philosophy of manures, it is idle to expect any benefit from its 
employment. 
The serpentine of Richmond county, assumes a great variety of 
forms, and passes into soapstone, talc, carbonate and hydrate of mag- 
nesia, while asbestus and amianthus are also frequently found in it. 
Similar series of minerals are found in the serpentine rocks of West- 
chester and Putnam, and to a certain extent, in those of Orange. At 
the north, some of these associates are also to be noticed, but as yet 
*See the appendix to this Report. 
