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GEMS AND PRECIOUS STONES. 343
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Peridot.—Peridot
has been obtained sporadically and occasionally in some quantities from
both the Navajo and the Apache Indian Reservations in Arizona. It is
collected chiefly by the Indians.
Turquoise.—Up
to 1888 the output of turquoise mining was small, but regular mining
was then begun first at Cerrillos, NT Mex., and later in the Burro
Mountains, N. Mex., and in Saguache County, Colo. The production rose
to $175,000 in 1892. Arizona, California, and Nevada have since
entered the list of turquoise-producing States, and little contributed
large quantities at different times. The climax in the production of
turquoise came in 1909 when more than 17 tons of turquoise and matrix
was mined. The value of this rough product was estimated at about
$179,000.
Feldspar gems.—Amazon
stone is the principal feldspar gem mined in the United States. The
Pikes Peak region of Colorado has continued to yield a quantity of
this stone nearly every year. Amelia, Va., has been another source of
supply of much good grade of amazon stone.
Other semiprecious stones.-—The
production of numerous other gems has been quite variable. The
thomsonite and chlorastrolite beach pebbles of Isle Royale, Lake
Superior, have been gathered more or less regularly by tourists each
year. Other varieties of beach pebbbles are collected for ornamental
purposes along the Pacific coast. Of the numerous other minerals
sometimes used for gems or ornaments mentioned as known in 1882,
rhodonite, malachite, rose quartz, and catlinite have been used in some
quantity.
New qem minerals.—Among
new gem minerals may be mentioned californite (massive compact
vesuvianite), and benitoite both found in California. Californite has
been found in several counties and a quantity has been sold at
different times. Benitoite is a barium titanosilicate. It is a new
mineral discovered in San Benito County in 1906. Only one deposit, now
exhausted, has been found. Benitoite is a blue mineral resembling
sapphire in color but much softer. It has a high refractive index and
strong dichroism.
Below
is given a table of the production of gems and precious stones as
recorded in these reports from 1883 to 1914, inclusive. Difficulty was
encountered in deciding on the statistics for the earlier years, as
there were discrepancies between the tables of production given year by
year and those showing the production for periods of years. The figures
used are those which seem most reliable.
The
tables of production are not given as exact statements, but represent
the best estimates that could be made each year. During the last 20
years the statistics include exact figures of production for some
minerals and estimates for others. The tables of production for the
years 1883 to 1905, inclusive, were prepared by G. F. Kunz. The value
of the total production for the years 1883 to 1914 amounts to
$7,799,971. Kunz has made an estimate of the total production for the
three years preceding 1882 as follows: 1880, $100,000; 1881, $110,000;
1882, $150,000. This makes a grand total of the production of gems and
precious stones in the United States from 1880 to 1914 of $8,159,971.
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