THE MINERAL INDUSTRY OF NEW HAMPSHIRE 
 
 
REVIEW BY MINERAL COMMODITIES 
537 
 
NONMETALS 
 
 Clays.—Production of clay declined nearly 18 percent from that of
1966. The decline was caused mainly by the closing in late 1966 of the Eno
Brick Corp. in Rockingham County. Clay from pits operating in Grafton, Rockingham,
and Strafford Counties was used principally in manufacturing building bricks.

 
 Feldspar.—Potash feldspar was produced from only one pegmatite mine
during 1967. The Ruggles mine in Grafton County was operated by the Ruggles
Mining Co., Inc., the major part of the year; Bell Minerals Co. took over
operation of the mine in December. Total value remained about the same as
1966, but production of crude feldspar declined. Unit value of crude ore
increased, partly because of increased transportation costs. Ore was selectively
mined and hand sorted. Lump feldspar was shipped by truck to a feldspar grinding
mill at West Paris, Maine. The finely ground feldspar was used primarily
in ceramics and as an abrasive in cleaning compounds. 
 
 Gem Stones.—Curio dealers and amateur mineral collectors recovered
semiprecious gem stones and other mineral specimens from various locations
within the State. Principal areas of interest were associated with pegmatites
in Cheshire, Carroll, and Grafton Counties. Material recovered included beryl,
amethyst, smoky quartz, and topaz crystals, including some of gem quality.

 
 Mica.—Block mica was produced at the Ruggles mine in Grafton County.
Material was shipped to an independent trimmer in Gilsum, Chesire County,
for preparation. Because of its low electrical and thermal conductivity and
tolerance to fairly high temperatures, trimmed mica is ira- 
portant in the manufacture of electrical and electronic equipment. 
 
 Peat.—No peat was produced during 1967. Perkins peat bog in Belknap
County was idle, but sold about 50 tons of previously recovered reed-sedge
peat from stock. Material was used primarily as a soil conditioner. 
 
 Perlite.—National Gypsum Co. at its plant in Portsmouth expanded perlite
for use in acoustical plaster. Production of expanded perlite declined during
the year, with a decrease in total value of 13 percent. Unit value increased
12 percent during the same period. The raw material used was crude perlite
imported from the Western States. 
 
 Sand and GraveL—The 0.8-million-ton increase in production, compared
with that of 1966, was utilized in highway construction. Sand and gravel
produced by Government-and-contractor operations increased 21 percent in
volume and 31 percent in value over the 1966 production, reflecting an increase
in the number of active State and Interstate highway projects. Commercially
produced material decreased 1 percent in volume and 3 percent in value. However,
the average value of washed and screened material from commercial plants
increased from $1.08 to $1.12 per ton, and unprocessed material increased
6 cents to an average value of $0.46 per ton. Bank-run sand and gravel accounted
for 31 percent of commercial production, compared with 21 percent the previous
year. Of the 30 commercial sand and gravel operations reporting production
in 1967, 11 had an output of less than 50,000 tons, nine produced 50,000
to 
100,000 tons, and 10 produced over 
100,000 tons each. Eleven percent of the commercially produced material was
delivered by rail, primarily to Boston, Mass., for use in ready-mix concrete.