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PRECIOUS STONES.
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819
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clay,
from which the sapphires were readily washed. As the work was carried
deeper, the dixe rock was less altered and hard, so that it has been
found necessary to disintegrate it in some way before washing. This is
accomplished by exposing piles of ore to the weather with occasional
wettings. The action of moisture and air, aided by the frequent
freezings and thawings of the winter climate, soon starts the slacking
and disintegration of the lumps of "blue," as the ore is called. The
disintegration is carried out on inclined floors or settling grounds,
where the ore is deposited after removal from the mine. After an
exposure of several months, a large stream of water is turned on the
piles of "blue," which are forked over at the same time. The
disintegrated surfaces of the lumps are washed off and down through a
sluice along with other loose disintegrated material. This leaves the
"blue" in apparently hard fresh lumps, which, however, soon begin to
disintegrate and crumble again. The material in the sluice is carried
over a set of riffles to a settling dam, where the lump material
brought down undergoes further disintegration. From the first settling
dam the "blue" is washed down over riffles to a second, for final
disintegration.
The
sluices are made of board and have iron-plate bottoms. Iron riffles are
placed at the proper places in the sluice to catch the sap-
phires,
and clean-ups are made four or more times in twenty-four hours, the
concentrates are separated in a rocker sieve into three sizes, and each
grade is panned down closer over a wooden tank. The oversize left on a
screen of f-inch mesh is carefully examined for large sapphires before
discarding. The contents of the tank in which the panning is done
receive further treatment on screens of two different meshes from those
first used. Sapphires are picked up by hand from the coarse sizes of
concentrates before shipping. The small sizes containing the culls for
watch jewels are shipped in the rough. All the sapphires go to the
company's office in London for cutting and marketing.
American Sapphire Company.—Through
the courtesy of Messrs. John T. Morrow and C. H. Burr, consulting and
attendant engineers for the American Sapphire Company, the writer was
shown through the plant of that company and was assisted in the
preparation of the following notes. The plant of the American Sapphire
Company, operating on the same gem-bearing dike as the New Mine
Sapphire Syndicate, is located in the canyon of Yogo Creek. The early
work by former owners on this portion of the sapphire-bearing dike
consisted of shafts and openings on the east side of the canyon. Some
of these were near the edge of the bench land above, and others in the
canyon walls. Prospects and shafts were also made across Yogo Canyon
and along a tributary gulch to the west. Three different dikes are
reported to have been located. One of these, in the bottom of the
tributary canyon, was opened several years ago by a shaft about 100
feet deep, and good sapphire ore was found.
The
mining of the dike rock by the present company is accomplished by
drifts with stopes under the cliff on the east side of the canyon and a
shaft at the mouth of the drift a little above the bottom of the
canyon. This shaft was about 70 feet deep in September, 1907, and in
pay ore. It was reported that the depth was about 100 feet early in
1908, and that the shaft was equipped with an electrical hoist capable
of sinking to 1,000 feet. The level of the workings in the
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