The Cook County herald. [volume] (Grand Marais, Minn.) 1893-1909, 1901-01-26
HOW TO Y ALUEA MINE
Experts Method Of Estimating the
Worth Of core in Sight,
Always an Element of Uncertainty
Even Under the Moat Advan- h
tageous Investigations OF
Deposits.


of the Independence gold mine had
been accepted BY. the London owners
came the report that the mine had
been worked out" This statement
had been made many times before, and
much doubt existed in the minds Of
interested parties when Mr.. Ham,
mond's latest report was received.
says the New York Tribune. This
document showed that the property
which for 3 long time yielded a 40 per
cent. dividend on q large investment,
was still rich in ore, and capable Of
producing large profits. Mr.. Ham
mond said that the lore in sight" war
ranted him in guaranteeing divi-
dend of ten per cent, or $4Ss, 1000, and
that would leave about 100000 out of
the years deposits to be used toward
the further development of the prop
erty and locating new ore beds.
The phrase ''ore in sight" is one
that is well understood by people who
are interested in the mining business,
but is misunderstood by the average
layman. The ore is not ''sin sight" on
the surface, but it's existence is es-
tablished by a series Of. operations
which are in many instances exceed
ingly difficult, expensive and labori-
Gus.
Speaking ON this subject, DR.. A. r.
Ledoux said: '0rhere is no way to de-
termine the existence of gold ore, it's
quantity, quality, or anything about
itun1ess one gets on three sides of the
deposit, and even then there ls3an ele-
ment of uncertainty about it,. Ore in
sight is what has been found after
Blocking out a certain section Of
ground. The blocking is accom-
plished in various ways in keeping
with the nature of the ground. Thus,
by sinking shaft Of 20 feet in width
100 feet into the earth and then run
ming level from this, say 200 feet, to
another shaft the same depth and
width as the first, and then taking
samples of the ore or rock from all
parts of this block one would have
good idea of the yielding qualities of
that particular block. This block
would be 100000 cubic feet, or about
10000 tons, and the assays from the
four sides, the two shafts, the tunnel
and the surface would be the gold in
sight, The center of the block, which
cannot be- reached until actual opera.
tons are begun, might yield much
more than the assays indicated, and,
on the other hand, it might be found
worthless or barren rock. In cases
where the block of 1OOx200x2O feet
would be deemed insufficient for de-
fe rrn n o. the va 11a4nf the mine D.
other block OF similar size may ne
laid out below or beyond the first, and
by this series of blocking the value Of
the mine as gold producer is esti-
mated. 1t is well-known fact, that
gold is often deposited in shoots that
run in oblique and tortuous direc-
lions from the surface, and one must
be posted ON the geology of the coun-
try to arrive at a correct estimate OF
the value of the land that has been
blocked out. A shaft, for instance.
may run for 100 feet through rich ore
and another parallel shaft 200 feet
away may not strike any ore until q
depth OF 100 feet or more has been
reached. The next shaft 200 feet fur
Their away may have to be sunk still
further. before the valuable rock is
reached, and this would indicate that
the shoot runs diagonally from the
surface. This is only one of the many
phenomena in the matter Of gold veins
that present themselves to the miner.
and no set rule can be followed in or
der to locate the valuable ore or to
determine its extent. But the term
gold in sight or ore in sight is usu-
ally applied to the block or to the
series of blocks which have been ex-
amined and assayed on three Sides"