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 sufificiently 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 lo 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 



