breaking
down of a rock similar to this. It is evident that some out-croppings
have been eroded by glacial action north of all the bars, but from what
precise locality is not yet known. It can not have come from the dike
at Ruby bar, as this locality is 6 miles south of Eldorado bar, where a
quantity of sapphires were found, but rather from some others now worn
away or covered over farther to the north. Mining in this district will
probably bring to light other dikes, as did the drifting of a level at
Euby bar some hundreds of feet from the outcrop of the original 4-foot
dike. The rock is shown by Mr. H. Miers to be a vesicular
niica-augite-andesite, containing an abundance of brown mica and
porphyritic crystals of augite.(a) The ground mass consists chiefly of
feldspar micro-lites with a considerable amount of glassy interstitial
matter and much magnetite. Many of the cavities are occupied by a brown
glass which appears yellow in thin sections and displays a spherulitic
structure originating in the sides of the cavities.
It
is of course difficult to say whether or not the sapphires have been
caught up by the augite-andesite from schists or other rocks cut
through in coming up, as may have been the case in the occurrences in
the Eifel Laacher See, at Unkel, and in Auvergne at Espailly, France.
Owing
to the prominence given to the Montaua sapphires by the press some
thousands of these stones have been sent east and to other centers by
the people residing in the vicinity of the district where they are
found, for cutting. The result has been that many of them have been cut
in the belief that they have a value as gems far beyond their true
commercial one. With them many garnets also have been sent frequently
exceptionally fine in color.
Emerald.—The
mining for emerald and lithia emerald has been carried on for ten
years by the Emerald and Hiddenite Mining Company, organized in 1881,
with a nominal capital of $100,000. Work was carried on for some time
during the summer of 1891, and about 1,500 carats of lithia emerald
(hiddenite) and a few small emeralds were obtained, although all were
of little value.
Turquois.—During
1890 and 1891 turquois of fine quality and of gem value has been found
in the United States. The main locality is the one near Los Cerrillos,
New Mexico; the others known are in Grant county, New Mexico.
During
the early part of 1890, what is known as the Castilian turquois mine
was leased and a number of men put to work by Mr. J. A. Allen, of
Chicago, Illinois. This mine is 7 miles from Los Cerrillos, New Mexico,
on the road from that place to Santa Fe, and about 1-1/2 miles from
Bonanza, with another one adjacent to it. At both these places an
immense amount of working was done centuries ago by the Indians, as the
hundreds of stone hammers observed by the writer indicate. This
property has been opened during the past year, a shaft has been sunk 75
feet, and a lode opened for about 40 feet. The vein or
