70 GEMS AND PRECIOUS STONES IN THE
resulted
in the finding of large quantities of fragments. This locality
furnished good, clear, and distinct crystals of topaz and has yielded
the best crystals found in the East. The specimens are either colorless
or faintly tinted with green or blue. The finest crystals were from 2/5
inch to 2 1/2 inches (10 to 65 millimeters) across, perfect,
and in part transparent. Several perfect gems have been cut from some
of the fragments. They had the characteristic fluid cavities, and in
hardness were the same as the Brazilian.1 Some white opaque
crystals, a foot in diameter, were blasted out by the writer. The
finest crystal found at this locality is in the cabinet of Clarence S.
Bement. (See illustration.) During 1888 nearly 100 crystals associated
with phenacite were found on Bald Mountain, North Chatham, N. H., which
is only a few miles from the Stoneham locality, both places being near
the State line.2 They were colorless, light-green, or
cherry-colored on the outer sides and colorless in the center. The
largest crystal measured 1 1/2 inches in height and the same in thickness. Almost all the crystals contained irregular hollow spaces from 3/100 to 3/10 inch
(1 to 10 millimeters) across. In habit the crystals closely resemble
those from Cheyenne Mountain, Col. Some of these crystals are equal in
point of quality to any found in Colorado, although they are not as
large. At Stoneham, Me., green and red damourite, altered from topaz,
has been cut into different odd forms and charms by the local
collectors.3
TOURMALINE
belongs
to the rhombohedral system, and occurs in prisms, the sides of which
are generally striated and channeled. The hardness of the transparent
variety is 7.5, and its specific gravity ranges from 3.0 to 3.25. Its
composition is very complex, as is
shown in the table of analysis.
The question of color is an interesting one, particularly
when the varying colors of the lithia tourmaline are concerned.
The color of the iron and magnesian varieties depends on the
amount of iron present, and passes from the colorless specimens
1
See Topaz and Associated Minerals from Stoneham, Oxford County, Me. Am.
J. Sci. III., Vol. 25, p. 161, Feb., 1883 ; and Vol. 27, p. 212, March,
1884.
2 Am. J. Sci. III., Vol. 36, p. 222, Sept., 1888.
3 Am. J. Sci. III., Vol. 29, p. 278, May, 1885.
