92 ECONOMIC GEOLOGY, 



Polishing Powder. 



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 

 ;^I5 to $i8 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 



