BUILDING MATERIALS. 89 
admirably shown upon the map. At almost any part of this range these 
coarse granite veins are liable to occur. Masses of it a foot square are 
common wherever the veins have been opened. It is now thrown away 
because it cannot be utilized.. Our feldspar has been successfully used 
in the manufacture of artificial teeth by several dentists. The time is 
coming when our immense supplies of feldspar will be utilized. We 
have no beds of kaolin or porcelain clay that are of value. Quartz, valu- 
able for the manufacture of glass, is exceedingly common. The ranges of 
it which I have represented upon the map, and fully described in Volume 
II, are nearly all sufficiently pure for this purpose. These occur, first, 
through Hillsborough, Rockingham, and Strafford counties on the east, 
and from Cheshire to Grafton on the west side of the state. Very fre- 
quently there are large hills, hundreds of feet high and broad. In Lynde- 
borough there is an establishment fitted up for the manufacture of glass, 
based upon the presence of one of these beds of quartz. Although milky 
white, the quartz contains a small percentage of iron, and is therefore apt 
to impart a green color to the bottles manufactured. The iron is removed 
by first burning the stone in a kiln, so as to magnetize the hematite and 
limonite present; secondly, the brittle calcined rock is pulverized; thirdly 
and lastly, the powder is caused to fall over revolving cylinders bristling 
with magnets. These attract the iron, and thus purify the pulverized 
material, which is now ready to be put into crucibles. A very large busi- 
ness is done at Lyndeborough. 
Mica. 
Our state is celebrated for its mica. It occurs in enormous quantities, 
suitable for commercial use, in immense, coarse granite veins, where the 
three mineral constituents are found in large pieces. The mica I have 
seen in plates a yard long, but 10 or 12 inches is a more common size. 
On account of the great value of this mineral, we have taken special pains 
to learn where it is distributed, as it does not occur at hap-hazard any 
more than veins of the metals. Upon the. map we have distinguished a 
mica schist with fibrolite, one of the supposed divisions of the Montalban 
group. It is usually about two miles wide, and reaches from Easton to 
Surry, with occasional interruptions. It is extraordinarily developed 
about Rumney and Hebron, spreading out to fill the space between the 
VOL. Vv. 12 
