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PRECIOUS STONES.
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SMITHSONITE.
Translucent,
apple-green smithsonite, not only furnishing beautiful cabinet
specimens but cutting pretty gems, has been found in large masses in
the Magdalena mining district, New Mexicco. This smithsonite occurs in
the Kelly mine, which is being developed by the Tri-Bullion Smelting
and Development Company. It was found in a zinc vein in a cavity or vug
several feet wide and 25 feet long, which it lined and partly filled
with odd-shaped masses. The surface of the smithsonite masses has a
mammillary structure which is drusy with the edges of many small
projecting crj'stals. The mineral assumes odd shapes and sometimes
nearly a globular form. One specimen, seen in the New York office of
the Tri-Bullion Company, was roughly about the size and shape of the
head and bust of a man. It had a beautiful light-green color and was
covered with drusy mammillary lumps an inch or two across.
This
green smithsonite occurs in shells or layers, up to an inch or two in
thickness, coating rough, irregular masses of typical dry bone or
carbonate zinc ore. The shells of smithsonite have a columnar
structure across them, with a slight radial arrangement of the columns.
Ordinary smithsonite or zinc carbonate is colorless or white. This
material contains variable quantities of a copper salt, which give it a
beautiful green color. The copper stain is not evenly distributed
through the mineral, but occurs in layers parallel with its surfaces.
This smithsonite is being cut and sold as a gem in some of the Western
States. It yields handsome cabochon stones similar to chrysoprase,
though of course not so hard and therefore less valuable than that
mineral. Mr. Hart, of Manitou, Colo., reports that the rough mineral
for gem purposes brought from $2 to $5 per pound at Magdalena.
SPHALERITE.
Dr.
George E. Ladd reports that sphalerite crystals from the zinc-lead
mines of Missouri are used locally in jewelry without cutting. The
clear, rich, resin-colored crystals make handsome stick pins. The
mineral is too soft, however, for extensive use.
SPODUMENE. KUNZITE AND HIDDENITE.
United States.—There
was a large production of lilac-colored spodu-mene or kunzite in the
southern California gem region during 1907. The output of gem spodumene
amounted to about 125 pounds of selected material, part of which was
pale green, colorless, and yellowish. The production came from the
Pala Chief and the Caterina mines, near Pala, and the Mack mine, near
Rincon, all in San Diego County.
The
development for the emerald-green spodumene or hiddenite deposit in
North Carolina was described under "Beryl." Further work on the lilac
and pale-green spodumene deposit at Andover, Oxford County, Me., has
yielded mineral of good color, though clear only in small patches. Mr.
F. G. Hillman reported surprisingly beautiful gems cut from material
that had been pronounced valueless by two dealers in precious stones.
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