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560 MINERAL RESOURCES.
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Sussex
county, New Jersey, but although they are an important addition to our
mineralogical collections and the outer parts of some of the crystals
are of a rich almost chrome green, yet not a single one was observed
which would cut a transparent gem of even a few carats.
Prof.
E. B. Biggs, of the laboratory of the Geological Survey, recently made
over 25 analyses of tourmalines of all colors. He found the question of
the color of the lithia tourmaline a very interesting one. The color of
the iron and magnesian varieties depends on the amount of iron present.
It ranges from the colorless De Kalb through all the shades of brown to
the Pierrepont black, while the lithia tourmaline, containing more or
less manganese, gives the red, green, and blue, as well as the
colorless varieties. The shades of color do not depend on the absolute
amount of manganese present, but rather on the ratios existing between
that element and iron. Thus, when the amount of manganese bears a
specific proportion to the iron, we have the colorless, pink, or very
pale green tourmaline. An excess of manganese produces the red
varieties; and if the iron is in excess the various shades of green and
blue result.
Rubellite.—Mr.
William Irelan, jr., reports the finding of transparent rubellite in
fine crystals 1 to 2 inches long, in San Diego county, California.
Hiddenite.—Rev.
Alfred Free, in a report on a placer mine at Bracket Town, McDowell
county, North Carolina, mentions the finding of a small crystal of
spodumene of the hiddenite variety. He had also observed blue, green,
and pink tourmaline at the same locality.
Rock crystal.—In
the last report reference was made to the occurrence of rock crystal in
what was believed to be a part of Virginia, but which, on visiting the
locality, the writer found was really the mountainous part of Ashe
county, North Carolina. My attention was first called to this locality
by the receipt thence, by Messrs. Tiffany & Co., of a 51-pound
fragment of a large crystal, which was said to have been broken from a
mass weighing 300 pounds by a twelve-year old mountain girl. This large
crystal was found on the Mintor Blevin farm on Long Shoal creek, in
Chestnut Hill township, though crystals have also been found at two
places 600 feet apart on the L. C. Gentry farm, about oue mile from the
former locality. All three places are 50 miles from Abingdon, Virginia,
and 40 miles from Marion, Virginia. Crystals have also been found close
to the north fork of Piny creek, on the Saint Ledger Brooks farm. At
the latter place was found a remarkably clear distorted crystal,
weighing 20-1/2 pounds, which is absolutely perfect, and is the finest
piece of rock crystal ever found in the United States; and on the
Gentry farm one crystal was found weighing 188 pounds, and another
weighing 285 pounds. The latter was 29 inches long, 18 inches wide, and
13 inches thick, showing one pyramidal termination entirely perfect and
another partly so; it sold for over $500 for use in the arts. A number
of others have also been found. All these localities are on a spur of
Phcenix mountain, and the crystals have all been found in decomposed
crystal-
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