The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1899-01-02
THE TELLURIDE FAMILY.
Tests to Be Made to Determine Its
Presence.
nenver ReDlIblican.

Denver Republican,
The tellurides are compounds of the
metal tellurium with other metals. 1t
is usually assumed that the precious
metals enter into their composition and
a high commercial value is taken for
granted when this species of mineral is
referred to. However, the varieties in
clude many ores valueless to the gold
miner, such as the tellurides of mer-
curry, lead, bismuth and nickel, occur
ring for the most part in quantities so
restricted as TO be merely curiosities
much desired by the collector Of miner
ais.
Miners often exhibit confusion in the
use of the terms employed to describe
the various ores of tellurium, so that
it may prove useful to offer a few notes
which Will serve as a guide to those
who have not easy access to mineral
collections. Any one wishing TO give
a practical application to the informa-
ton contained in this contribution can
do so by visiting the state mineral eX-
hibit at the capitol, where heI will find
a very fine collection of tellurideS,
gathered together by the indefatigable
labors of Mr.. H. A. Lee, the commits
sioner of mines. 1t should be needless
to state that one cannot study miner
alogy without seeing and handling
minerals.
1t is a frequent custom in the min
ing camps to speak of ''tellurium"
when il is intended to refer not TO that
element itself, but to its compounds
with gold and silver. Tellurium is a
metal, it occurs native that is, in
free state, just as gold and silver do.
1t is tin-white in color, soft, but brit
tie. and usually occurs in a granular
massive condition. It's commercial
value is 49, so per ounce, but the demand
for it in the arts is very slight, and
few shipments quickly demoraliZes the
market, as is the case with most of the
rare metals.
In Boulder county native tellurium
often occurs in gold ores, and a mass
of twenty-five pounds was once found
in the John Jay mine, near Jimtown.
TEST FOR TELLURIDES.
All the tellurides have a rich metal
lie lusteT, most of them are steel-gray
to iron-black in color, and they are all
heavy, ranging in specific gravity from
seven to nine. If a mineral is suspected
Of belonging to this class, remove a
small bit of it with the point of a knife
and put it in a porcelain or white
saucer. Then add "a couple of drops of
strong sulphuric acid and heat it over
a lamp. Should tellurium enter into
the composition of the suspected min
eral, you viii quickly see a beautiful
purple suffuse the colorless acid. The
miners time-honored test is to put the
specimen in the fire of a blacksmith'S
forge, where it is roasted. Tellurium
fuses at a low temperature and be
comes vOlatized, passing off in white
fumes of telluric oxide. If there be gold
present it remains in globules. If more
precious telluride be hidden in cracks
within the specimen, the gold will be
excluded in a yellow perspiration. The
experienced miner has learned that not
all telluride ORE is rich, from the dis
appointing returns of many a. ship
ment to the smelter. and while he does
not know whether the delusive min
eral be native tellurium or a compound
of one of the baser metals, he does
know-that gold may be absent and
that a rough test, such as roasting, is
of assistance.
The Boulder miners are apt to call
everything native tellurium which does
not stand the test, but ii should be
pointed out that the experiment would
fail to distinguish the telluride of mer-
curry, because mercury volatizes easily
and passes off in fumes. The-telluride
of mercury is called coloradoite, be-
cause it was first found in this state,
in the Mountain Lion mine at Magno-
liza 1t occurs quite plentifuliy in the
ores Of Kalgoorlie, the great telluride
district Of West Australia. A simple
test is to roast a particle in a glass
tube, when the mercury liberated at the
hot end will pass off in fumes, which
will cOndense into metallic globules at
the upper or cooler end of the tube.
COloradoite is grayish-black and has
rich luster. The pieces which l Sc
cured at Kalgoorlie have a peculiar
brown tinge, unlike the Boulder speci-
mems An impure variety, containing
gold and silver, as well as mercury, has
been named kalgoorlite, after the place
of its discovery