Elk City mining news. (Elk City, Idaho) 1903-1913, 1905-10-28

solution of iron sulphate is said to have
the power to dissolve gold in much the
same manner as solutions of potassium
cyanide If this be true in nature (as
it is known in the labratory) then the
iron sulphate solutions slowly dissolve
to very fine gold, and reprecipitate it at
convenient places in it's downward flow
at the intersection of the vein with
floors, cracks, seams, and with other
veins. The pocket hunter is familiar
with these accumulations of gold, at
what he knows as crossings" A floor
or fault in vein usually results in en-
riching that portion of the vein imme-
lately above the floor or fault plane,
and often there is little or nothing be-
low it. Instances of this character are
particularly numerous. Another locus
If enrichment is in those portions of the
vein where there is a fiattening in the
lip, forming sort of roll or floor, on
which there is often an accumulation of
richer ore, and sometimes a pocket.
A careful study of the occurrence of
gold in pocket mines would probably
throw much light on the subject of ore
deposition and particularly on the sec
0ndary enrichment of gold-bearing veins
and deposits. The richest pockets ever
obtained from California mines were
found near the surface, or at least in
the oXidized zone. The noted mass of
gold found on Carson hill, in Calaveras
county, at the Morgan mine, in 1850,
occurred at the surface, the entire
amount coming from the surface pit
lot over 80 feet deep. Other large
pockets were found near the surface.
he largest pocket found in the Bonanza
nine at Sonora, in Tuolumne county,
vas obtained within 100 feet of the
surface-vertical measurement. Other
noted pockets in other mines have been
| found at or near the surface, while COM
| oaratively few-and no very large ones
have been discovered at great depth.
A noted writer stated recently in a
current publication that it was doubtful
any gold mine was as rich below 1000
'eet from the surface as it had been
lbove it. There are many instances to
prove that this statement is not borne
,ut by the facts, for in California there
re numerous mines which have proved
20 be richer below 1000 feet than above
hat depth. Among the mines illustrat-
ng the fallacy of this supposition are
he Kennedy mine and Argonaut, near
Jackson, the Central Eureka and Eureka
mines, near Suffer creek, and some of
he mines of the Grass Valley region.
Then there are mines that continue
to be largely profitable below 1000 feet
which also have been good above it, but
cannot be said that this richness, nor
chat of the mines previously mentioned
as being better below the 1000-foot
level than above it, are due to secondary
enrichment. In these cases the condi-
lions seem to be normal. To what depth
the payable ore Tor ore of the same
grade as that now being minedD will
continue, it is, of course, impossible to
predict. AS mining operations go deep
er, the cost per ton usually increases
somewhat, while the grade of ore may
not improve, if it even remanin as good
as it is at present levels. Secondary
enrichment, however, is a different
proposition, and there are those that
even say that no payable ore will be en-
countered below the zone of downward
circulation of surface waters; but those
who profess this belief fail to point out
clearly where this level is to be found.
Payable ore is still found in the deep
est gold mines of the world-those of
Colorado, California, and Victoria, Aus
tralia. The latter are down 1000 feet,
with pay, ore still in sight. The deepest
Californi q mine is down 29OO feet, with
good ore in the lowest level. Some Col
orado shafts have been penetrated be-
low the 1000 level and the mines still
are prosperous. At what level may we
expect them to become barren? Deep
mines may become Improbable because
of increased expense, while the value of
the ore remains the same as above. On
the Rand, in the Transval, for instance,
the gold-bearing banket continues to
produce nearly the same average values
as above, while the expense of mining
increases as the levels are carried to
deeper and still deeper levels, this be-
ing due entirely to economic and not
geoloeica conditions.