92 ECONOMIC GEOLOGY. 
PoLisHING PowpeEr. 
Chapter XIV, Volume I, is devoted to a description of the organisms, 
which by their decay give rise to the white, light earth sometimes called 
infusorial silica. It is liable to occur beneath any bog in the state. The 
few deposits we have are of excellent quality, and the quantity is suffi- 
cient for commercial use. The largest deposits are at Umbagog lake, 
Fitzwilliam, Stark, Tamworth, and on Stamp Act island, Wolfeborough. 
Others are known to exist at Bemis lake in Livermore, Littleton, Laconia, 
Bristol, Chalk pond in Newbury, Epsom, Bow, in a pond north-west from 
the Crawford house, White Mountains, Concord, Manchester, Durham, 
Grafton, and Exeter. The Fitzwilliam deposit is sold extensively for a 
polishing material. The principal use made of this article at the present 
day is in the manufacture of dynamite, and it commands a price of from 
$15 to $18 per ton. The most northern locality is in Cambridge, upon 
Umbagog lake, near W. M. Thurston’s, where it occupies, in the lake, on 
the islands, and on projecting points of land, an area of fifty acres or 
more. It varies in depth from a few inches to two feet, although, as our 
observations were limited, the depth may be in places much greater. It 
is covered in the lake by a lacustrine deposit, and on the islands by an 
accumulation of soil. 
In the town of Stark we find it in Pike’s pond. It is here known to 
be three feet in depth, and it is probably much more. It seems to be 
distributed over the entire bottom of the pond. 
WHETSTONES. 
These are quarried in Piermont and Haverhill by Mr. Pike. I have 
not his figures for the number of stones produced; but the business is a 
large one, and the material is inexhaustible. Other towns along the Con- 
necticut river contain the same rock. 
Two localities of novaculite or oil-stone are capable of supplying plenty 
of oil-stones. One is upon Fitch hill in Littleton, near the Helderberg 
fossils; and the other is at the north base of the Ossipee mountains. 
The place may be known by the fact that certain dark streaks in the 
stone have been mistaken for the rocks accompanying coal. Parties in- 
terested in selling the “mine” procured bits of bituminous coal from a 
