or
earlier "mound-builders" (if these indeed be distinct peoples), or
both. Ornaments cut from mica, as also shells and quartz crystals, are
not uncommon in the burial-mounds of the Mississippi valley; and, as no
mica occurs in that part of the country, it is clear that the old
excavations, rudely made with stone tools, along the outcrops of large
mica veins in North Carolina, were the source of this material, which
was evidently prized by the prehistoric tribes and widely distributed
among them.
It
is a " far cry" from prehistoric mounds and ancient and long-forgotten
mica mines to the incandescent lighting of our present civilization
and the properties of rare chemical elements. But such are some of the
contrasts that present themselves in speaking of North Carolina
minerals. It is now some 18 years since the introduction of the
Welsbach incandescent burner, or rather mantle, that has so improved
our gas illumination. Instead of using the light produced by white hot
carbon particles, as in ordinary flame, a hood or mantle is employed,
which, when heated by the burning gas, glows with far greater
intensity. This mantle consists of a loosely woven fabric impregnated
with certain compounds of rare elements. The first forms of it employed
zirconia salts; and this fact led to active mining of the small,
opaque, and previously unimportant zircon crystals that are abundant at
several points in North Carolina. Since then it has been found that
even greater brilliancy is obtained by the use of nitrate of thorium.
This latter is a rare metal, found in very few minerals and in small
amounts; but it is notably present in monazite, a phosphate of this and
other oxides of rare elements. Monazite was formerly regarded as a very
uncommon mineral, but it has been found to occur quite abundantly in
the sands of the stream-beds in the South Mountain region, comprising
several counties of North Carolina, being derived from the
disintegration of the country rock. Thus the monazite industry has now
become highly important, and it is likely to continue and increase; as
the demand for thorium salts for incandescent burners is very great.
This latest stage of North Carolina mining—the search for the " rare
earths," so-called—has developed extensively within a few years; though
General Clingman was active in the earlier stages of it, in promoting
the zircon mining, and Mr. W. E. Hidden first brought into use the
monazite sands, and induced the Welsbach Company to experiment with
them in 1884. In 1901 the monazite output of North Carolina was 748,000
pounds, valued at some $50,000. Only Brazil surpasses, or even
approaches, this production. In 1906 the output was 697,275 pounds,
valued at $125,510. A total of 8,426,004 pounds valued at $635,568, was
mined in the 14 years 1893 to 1906, inclusive.
With these general historical outlines in mind, we may pass to a more
