The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1918-08-01
DEPOSITS OF CHROM|TE
HOW AND WHERE FOUND
VALUABLE AND AUTHORITATIVE
INFORMATION REGARDING
DESIRED MINERAL.

Through the courtesy of the Mining
and Scientific Press, San Francisco
the Miner has received copy OF
"Chromite," pamphlet prepared by
Albert Burch and Samuel H. Bobear
which contains much practical infor-
nation regarding the occurrence and
production of this mineral which has
become such an important factor in
government war operations. liberal
extract is here made from the public
alton. copy of which may be oh
tanned free upon application to Albert
Burch, Crocker building, San Fran
cisco:
Characteristics and Surface lndica
tions.
Chrome ore is found associated with
basic magnetism rocks, usually SER
pentine. 1t is, therefore, waste of
time to seek deposits in regions where
no serpentine exists. Wherever SER
pentine is found, chrome deposits may
exist and prospecting is warranted
The ore is heavy and dark. Float
is usually found near the deposits.
either in the gulches or on the hill
sides Immediately below them. 1t
may be necessary to dig shallow
trenches prosecuting the zone where
float" is believed to exist; the soil
and rock shoveled from such trenches
should be carefully examined for ore.
When float is found, it should be
followed to the point where it is most
abundant, and then, if no outcrop is
seen, trenches must be dug in order
to uncover the ore body. Occasionally
float cannot be traced to ore in place
This is due to the fact that the ore
body has been completely eroded.
The prospector should not let this
discourage him. Hundreds of tons
of such fragmental mineral have been
shipped. The ground may be plowed
and the soil screened, so that the
chrome may be sorted from the waste
by hand. If no pillow is available, pick
and shovel work may take it's place
The mining of float ore frequently
yields high grade product and may
prove most profitable operation.
Miners are beginning to understand
the characteristics of these deposits.
There are, however, many new ones
being worked by those less experience
ed, who make errors in estimating
the possible tonnage
In many cases the miner considers
ne Is opening an ore body occurring in
more or less irregular veins, and that
that of quartz veins Outcrops may
be found for a distance of several
hundred feet, and in such alignment
as to give the impression that the de-
posits are continuous. The handy
pencil is then put to work to calculate
that the average width of the ore body
is, say, II feet, the vein can be traced
for 800 feet, and the ore ought to per-
sist at least 20 feet below the surface,
giving, therefore, a total of 10000
cubic feet, which, at 10 eubic feet per
ton, makes 1900 tons of ore. This
amount is then offered for sale.
Chromite does not occur in veins.
In few cases long narrow lenses are
observed extending 100 feet or more
along the surface, and few feet wide.
The depth of the ore body can be de-
tarmined only by development work;
this usually involves mining the ore,
which, of course necessitates follow
ing the ore body.
Shape Of Deposits.
The irregular shape of chrome de-
posits often presents puzzling prob
lens. When deposit "pinches out"
good rule to follow is to dig little
further before abandoning the mine.
Under no circumstances should a.
stringer, a small ore shoot, be left un-
explored in the face of the working.
While it may not pay to mine so small
shoot, dig it out, as it may lead to
other lens. We have followed this
rule, and have been handsomely re-
warded for SO doing.
Origin.
10 understand why estimates OF
chrome ore cannot be prepared in
the manner stated, it Is necessary to
know something about it's origin
When two substances, one of which
is more soluble than the other, are
dissolved in water, and the water is
then evaporated, the least soluble
substance will crystalline out first,
During the period when the earth's
crust was forming, chrome was In So
luton, not in water, but in the molten
magma which formed rock on cooling
Chrome, being less soluble than other
substances present, was one of the
first to crystalline from the magnetic
solution. During this crystallization
the particles aggregated in irregular
masses When the cooling process
was complete and the entire mass
had become solidified, these irregular
bodies, which are designated lenses,
were probably near the bottom of the
formation in which they are found.
AS the weight of chrome ore is much
greater than that of the rocks in
which ~ 10 found n caoms urohable