No. 50.] 
86 
Of carbonate of lime, in the form of calcareous spar, and marble, there 
are several localities. The latter term, however, is usually applied 
here to a dolomite similar to that of Dutchess county, and which is found 
abundantly in the vicinity of Patterson. The only objection to this 
material for construction, is its friable character.* Being a compound 
of the carbonates of lime, and magnesia, it has been thought that the 
product of its calcination, is not so valuable, as a fertilizing agent, as 
that which contains lime alone. On this subject, however, as I have 
already remarked, mistaken views have been entertained, as some soils 
which appear to have been formed in part of the magnesian limestone 
are by no means wanting in fertility. It may be added that a white 
crystalline limestone occurs in this county which is entirely free from 
magnesia. 
A very valuable mineral product of Putnam county is serpentine, 
which exists in vast quantity, can be obtained in blocks of uniform den- 
sity, and is susceptible of a fine polish. But for the fact that the quar- 
ries of this beautiful material are situated at too great a distance from 
water transport, they would long ago have been extensively wrought. 
Of the precious or noble serpentine, also, there are several localities 
where the mineralogist may obtain specimens equal in beauty to any 
that are found in the United States. 
Among the objects worthy of notice in this connexion are two locali- 
ties of arsenical iron pyrites, one of which has at some former period 
been extensively wrought. This ore which might be used for the ex- 
traction of arsenic, seems to be abundant, but the present condition of 
the mine renders it diflicult to arrive at a certain conclusion on this 
subject. Its reported mixture with silver is probably one of those sto- 
ries circulated for selfish purposes, and the only ground for it in the 
present instance is, the fact that in other countries, the arsenical ores 
are often associated with those of a more valuable metal. 
I should not omit to add that a bed of limonite or hydrate of iron, 
occurs in Peekskill Hollow, near the line between Philipstown and 
Garmel. Mr. Mather, however, remarks that it seems to be too sili- 
ceous to work well alone in the furnace. There are also several locali- 
ties of peat, and probably marl will hereafter be found accompanying 
this substance as it does in several other counties. 
Putnam county has for many years been visited by mineralogists 
* The Putnam county dolomite often contains a large admixture of tremolite. 
