Chromite

CHROMITE

Mining and Scientific Press

San Francisco

1918

CHROMITE

By ALBERT BURCH and SAMUEL H. DOLBEAR

Sources and Uses.

Why Increased Production Within the United States is a
War Necessity.

Characteristics and Surface Indications.
Shape of Deposits.
Origin.

Distribution of Chrome in Deposits.
Field Determination of Chromite.
Minerals Mistaken for Chromite.

Methods and Costs of Mining.

Methods and Costs of Concentrating.

Methods and Costs of Transportation.

Proper Capital Investment.

Methods of Financing Operations.

Markets, Selling Conditions, Future.
Prices.
Contracts.

How to Make Shipments.
Specifications for Marketable Ore.
Methods of Marketing.
List of Purchasers.

Sampling and Analysis of Chromite. By Abbot A. Hanks.
The Determination of Chromium in Chromite.

387362

FOREWORD

This pamphlet has been written in response to a con-
stantly increasing demand for information regarding
chromite, its occurrence in nature, and the methods to be
used in its production and in marketing. Chromite is
one of the most important of the so-called war-minerals,
and the necessity for stimulating its production cannot
be over-rated. Through the generosity and patriotism
of the Mining and Sciem,tific Press, which has published
this pamphlet at its own expense, it is possible to dis-
tribute this without charge to those seeking information.
Acknowledgment is also made to Abbot A. Hanks for
the chapter on sampling and analysis.

Albert Burch.
Samuel H. Dolbear.
July 1, 1918.

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CHROMITE

Sources and Uses

Chromite, or chrome-iron ore, which is the only com-
mercially valuable ore of chromium, is found in Euro-
pean and Asiatic Turkey, Greece, Russia, India, New
Caledonia, Rhodesia, Canada, Cuba, and the United
States. Low-grade ores are also found in Germany, and
small deposits in a few other countries.

For many years most of the ore used in the United
States came from Asiatic Turkey, with the exception of
the small amount used on the Pacific Coast, this being
mined in California. Later, with the discovery of large
deposits in New Caledonia, that island became the chief
source of supply, not only for the United States, but for
Europe, and still more recently a considerable quantity
of high-grade ore has been coming from Rhodesia.

In the United States some important deposits in the
Eastern States were worked several years ago, but have
apparently become exhausted, so that now almost the
only sources of domestic ore are the serpentine areas of
California and Oregon, if we exclude from consideration
the newly discovered deposits of Montana and Wyoming,
the importance of which has not yet been demonstrated.

The chief uses of chrome ore are

(1) As an alloy for hardening and toughening steel,

(2) As a heat and acid-resisting lining for steel-
furnaces,

(3) For making dyes to color cloth (as, for instance,
khaki), and

(4) For the manufacture of chemicals used in the tan-
ning of leather.

Substitutes may be used for any of the purposes
named, but none of them will perform exactly the same
function as chromium ; and, in order to use them, radical
and expensive changes will have to be made in manu-
facturing equipment and methods.

Why Increased Production Within the United
States is a War Necessity

Chrome-steel is used directly in the manufacture of
axles, springs, etc., which form parts of gun-carriages,
automobiles, auto-trucks, and probably the famous
* tanks', all of which may be classed as 'munitions of
war*.

Chrome bricks and raw chrome ores are used to line
the furnaces that turn out 36,000,000 tons of steel per
annum, for no substitute is known the use of which will
not result in reducing the daily capacity of these
furnaces.

Chromium chemicals are used for dyeing the cloth that
goes into the manufacture of soldiers' uniforms and for
tanning the leather from which their shoes are made.

If the ore for these uses is not produced within the
United States, or Canada, it must come in ships from
abroad, and. as the supply obtainable from Canada is
quite small, and the output from Cuba only just begin-
ning, this means that it must come from New Caledonia
and Rhodesia, the European and Asiatic supplies being
either in enemy hands or in such locations that the ports
of export are closed by enemy fortifications. The fact
that the winning of the war depends upon the number
of men the United States can put in the field in Europe
is now so well known as to require no comment, and it
is also understood that the only limit to the number of
men we can send to the front is the number of ships to
transport them and keep them supplied with munitions
and food. For this purpose, a ship diverted from un-
necessary traffic is worth even more than a ship built,
because, with its crew, it is immediately available ; and
because it takes so much longer for a ship to make the
round trip with a cargo of chrome ore between the United
States and the ports of New Caledonia and South Africa
than between New York and the French ports, it is esti-
mated that releasing such a ship is equivalent to the
building of five. Reducing this to terms of chrome ore,
each thousand tons of such ore produced in California
will enable us to face the Kaiser with two thousand more
men.

~6—

Methods and Costs of Mining

The sudden and rapid growth of the chrome-mining
industry in California and Oregon has resulted in draw-
ing into it two classes of men, namely, those who have
had no previous mining experience whatever, and those
who have gained their experience from mining other
ores. It is hoped the remarks that follow may in some
cases be of use to the one class, and in some cases to the
other. To those who have had no experience, we would
say: get, if possible, a good mine foreman who has
learned his business from the bottom up, and who has
the knack of acquiring and holding th6 respect and good-
will of his men. The services of such a man are invalu-
able, and the price you can afford to pay for them is
limited only by the magnitude of the operation. Next
provide as good quarters for your men as the circum-
stances and probable duration of the operation will per-
mit, and then see that they get good food, even if you
seem to be losing money by supplying it.

In detail, the proper methods of mining will be gov-
erned by the circumstances surrounding each venture
and these will vary quite as much between different
mines as they will between those of enterprises based
upon the exploitation of other minerals, but the chapter
describing the irregularity and uncertainty of chrome
deposits emphasizes the fact that in the mining of chro-
mite more than that of any other mineral, the most im-
portant thing is to follow the ore. In doing this, any one
of three methods may be available, namely, open-cut,
tunnel, or shaft, of which the first is always the cheapest
and the last the most expensive.

An outcrop, no matter how small, may be the only
surface exposure of a large lens, or you may be able to
see in it ''all the ore there is". When such an outcrop
is found on a hillside, an open-cut should be started
upon it, and, if on level ground, a shaft should be started
in the ore. In no case should a tunnel be started in
barren ground for the purpose of driving under an out-
crop, until it has been demonstrated by shaft or winze
how deep the deposit goes, and then only after sufficient

other work has been done to prove that enough ore exists
to enable one to repay the cost of the tunnel out of the
difference between the cost of hoisting or shoveling it and
that of handling it by overhead stoping from the tunnel-
level.

Again, in the case of a deposit that must be worked
through a shaft, two questions may arise : ( 1 ) should the
working shaft be located in the orebody itself, or on one
side; and (2) what hoisting equipment should be used?

The first question cannot be answered until work has
been done on the orebody itself to determine its size and
shape. Should it prove not to be more than fifteen or
twenty feet deep, the hoisting could well be done through
an opening in the ore itself, for a windlass would prob-
ably be used and it could be shifted from one part of
the deposit to another without great expense. Should
the ore go to a greater depth, then its width, the shape
at the top, and the firmness of the walls would determine
where the shaft should be sunk ; for, if the orebody is
not more than about ten feet wide at the top, does not
expand with depth, and has walls of fairly firm rock,
then the head-frame may be placed on stringers spanning
the entire opening and no outside shaft will be needed.
On the other hand, should any one of these conditions be
reversed, it would probably be wise, in the case of a large
orebody, to sink a shaft in the country-rock a short
distance from the deposit after the preliminary prospect-
ing in the ore had been performed.

The second question must be determined by the quan-
tity of ore and the depth from which it is to be hoisted.
For depths not greatly exceeding twenty feet, hoisting
by windlass is probably as cheap as by any other method,
though even to this depth should the orebody be large
it might pay to carry an inclined track down through
the middle of the deposit and hoist by gasoline-engine,
steam, or, in a remote district, a horse-whim or 'whip'.
No hard and fast rule can be established, but, as in the
case of a proposed extraction tunnel, the probable num-
ber of tons available should be multiplied by the cost
per ton of hoisting when employing the method involv-
ing the smallest investment for equipment, and by the

—8—

cost per ton for each more expensive equipment. When-
ever the difference is sufficient to re-pay the cost of the
machinery less its salvage value, it should be installed.
Costs of hoisting by different methods vary so greatly
with different localities, depths, and tonnages, that no
attempt will be made here to list them.

Most of the chromite deposits of California and
Oregon are so small that drilling by hand is the method
that must be adopted, and actual mining by this method
is not as a rule much more expensive per ton of ore
broken than by machine-drilling; but the latter method
is much more rapid, thus reducing the overhead expense,
and where labor is scarce, as it is in war times, the differ-
ence in the number of men necessary to produce a given
tonnage is important. Therefore, whenever a deposit is
found that appears large enough (dividing the cost of
installation by the probable tonnage available), we would
advise the use of compressed-air drills, for driving which
there are several makes of portable and semi-portable
air-compressors. It would be manifestly unwise, how-
ever, to wait 60 days for the erection of a compressed-
air plant on a mine that could be worked out by hand in
that length of time.

When the deposit is not large enough to justify build-
ing a concentrator for the purpose of separating ore
from waste, it will be necessary to cob and sort the ore
in order to produce a shipping product. In such mines
a good foreman can frequently economize on the subse-
quent sorting by having his holes so placed as to break
the spots of clean ore separate from the mixed material.
This can be done more readily where hand-drilling is
used instead of machine-work. For the actual cobbing
it pays to provide special hammers formed like a geolo-
gist's hammer, but a little heavier; and it also pays to
dump the ore over an inclined screen, so that the sorting
is done upon the coarser material only. It also pays to
spray the ore with water before sorting, and it is sur-
prising how much spraying can be done through fine
holes in a tin can from a single barrel of water. It may
be found that the screening from one lot of ore is suffi-
ciently good to be shipped with the selected ore whereas

—9—

that from the next lot will fall short of the requirements.
If a good foreman be allowed, at the beginning of an
operation, to take frequent samples of the screening for
analysis, he will soon be able to judge fairly well whether
a given pile should be shipped or put aside for concen-
trating later.

The cost of mining, the product from a chrome mine
in California varies within wide limits, although the
actual breaking and tramming of the material from a
medium orebody should not exceed the following prices
per ton :

Hand-drilling' Machine-work

Open-cut »1.50 $1.10

Overhead sloping- from tunnel 2.25 1.75

Overhead stoping and hoisting- through shaft. 3.00 2.50

Underhand sloping: 6.00 5.00

Added to these costs, however, are numerous items of
overhead expense, which are frequently overlooked, for
example, amortization of plant, workmen's compensa-
tion insurance, taxes, loss on boarding house, superin-
tendence, sampling and analysis of samples, and various
other items, which, for even a large operation may easily
amount to a dollar per ton and for small ones may
amount to several dollars per ton. What causes the
greatest variation in the cost of mining, aside from dif-
ferences in the size and form of the orebodies, is the rela-
tion between quantity of ore mined and of product ship-
ped, for according as the ore is clean or badly mixed
with waste, the sorting may range from as low as two
dollars per ton up to as much as twenty.

Methods and Costs of Concentrating

Many deposits of chromite that are too low-grade to
be marketable will yield a good product as the result of
concentration, but, before building a mill for that pur-
pose, careful consideration should be given to some im-
portant questions.

(1) What profit per ton will the ore yield after pay-
ing all costs, including mining and concentration f

(2) How many tons are available, and is the quantity
sufficient to re-pay the cost of the mill, leaving a profit ?

(3) Is there an assured supply of water sufficient for

—10—

the tonnage to be treated? About seven tons of water
is required for each ton of ore.

(4) Is the ore itself amenable to concentration?
What percentage of recovery and what grade of concen-
trate can be obtained?

(5) What is the type of equipment best adapted to
the treatment of this particular ore ?

The gravity concentration of chrome ores is an ex-
tremely simple operation, because the specific gravity of
chromite is nearly double that of the usual gangue, which
is mostly serpentine. The grade of the concentrate is
determined not so much by the percentage of gangue re-
maining in it as by the grade of the clean mineral itself,
which is variable.

For the final crushing of the ore after it has passed
through the ordinary rock-breaker, a machine should be
selected that will give a maximum of crushing capacity
with a minimum of sliming. For this purpose we favor
rolls. This practice has not been followed, however, by
most mill-builders in California, where ball-mills and
even stamps have been used for the final crushing; but
whether this has been the result of careful design or due
to the necessity for quick delivery of equipment is not
known — the latter reason seems the more probable. Fol-
lowing the final crushing it has been the general prac-
tice to pass the material through some type of classifier to
separate the sand from the slime. The sand is then
passed over tables that discharge concentrate, middling,
and tailing, while the slime is treated on tables the prod-
ucts of which are concentrate and tailing. The middling
from the sand-tables, without further grinding, is re-
concentrated on another set of sand-tables.

Such a concentratol-, including a rough building and
gasoline-engines for power, can now be erected at points
near a railroad in California or Oregon for about $300
per -ton of daily capacity, or, say, $15,000 for a 50-ton
mill.

It is our belief that, because of the difference in the
character of the ore in various deposits, such an im-
portant thing as the construction of a mill should not be
undertaken without first having made preliminary tests

—11—

upon the ore in a properly operated testing-plant and
that then both the crushing and concentrating equipment
should be selected to fit the requirements of the ore to be
treated, and as most of the chrome ore that has come
under our observation has been comparatively coai*se in
texture it is believed that for most cases, the equipment
desirable will be about as follows: Rock-breaker, rolls
working in closed circuit with a 4 to 6-mm. trommel, fine
jigs, rolls for jig-middling, working in closed circuit
with Bunker Hill or Callow screen, classifier dividing
the product to sand and slime tables, stationary canvas
plant after slime-tables. Such a plant should not cost
much more than the other type and on most chrome ores
the percentage of recovery should be higher. Naturally,
where fine grinding is really required for the purpose of
liberating the mineral, ball-mills will be introduced for
this work.

The recovery of chrome ore by concentration in Cali-
fornia should be fully 75% of the mineral; with careful
work and some refinements in practice it might be
brought well above 80%. Too much money cannot, how-
ever, be expended upon refinements for the benefit of a
short-lived enterprise. The cost of concentration may be
expected to range from less than one dollar per ton for
a well-constructed 100-ton plant driven by cheap electric
power up to two dollars, or more, for a small poorly con-
structed mill using gasoline-power.

Methods and Costs of Transportation

Under this heading we must note again the great dif-
ference in circumstances affecting individual cases. One
mine might be large enough and rich enough to justify
the construction of several miles of expensive truck-
road, or even railroad, while a mile of trail construction
might be more than another one could stand. Whether
a man shall 'sled' his ore down from a hill at a cost of
$10 per ton instead of building a road for $2000 over
which it will cost him $2 per ton to haul it, will depend
upon whether he has at least one-eighth of 2000 tons to
haul. This applies to all other questions relating to the
kind of transportation to be used.

—12—

The following figures, as to costs in California and
Oregon, are believed to be fairly accurate at the present
time :

Per ton-mile

Pack-animals over roug-h mountain-trail at 200 lb. per

animal where all the feed must be imported $2.50 to $3.50

Pack-animals over rough mountain-trail at 200 lb. per

animal when g^razingr is good 2.00 to 2.50

Hauling by team over mountain-roads too steep for motor-
trucks at 1000 to 1200 lb. per animal 0.60 to 0.60

Motor-trucks over hard mountain-roads 0.25 to 0.40

Pack-animals can average not more than 15 miles per
day when loaded, and about 18 miles is a good day^s
work for a freight team.

For pack-animals and freight teams round trips con-
suming less than one day are less economical in cost per
ton-mile than those requiring more time ; and for motor-
trucks round trips requiring exactly one day are the
most economical. For trips of one day or less kyaks in-
stead of bags are recommended for packing, because
they are so much cheaper and easier to load and unload.

The cost of roads and trails varies so greatly in moun-
tainous regions that it is not advisable to begin any im-
portant construction of this kind without a survey and
an estimate of cost by a competent engineer.

Proper Capital Investment

If the reader has studied the chapter describing the
nature of chrome deposits, he will realize that the out-
right purchase of undeveloped prospects and even their
development if situated at points remote from transpor-
tation, is a risky business; but, aside from the uncer-
tainty of the market, it is perhaps no more risky than
that of the average mining exploration and not nearly
so risky in proportion to the capital invested as that of
the average prospector who stakes his entire fortune
(which happens to be his life) on the chance of making
a good discovery.

A safer plan, and one fairer to the investor, is the
leasing system, with or without an option to purchase;
and, except for unusually promising ground to be had for
a low figure, it is the only one that we would be disposed
to recommend. The risk will then be confined to the

—13— .

money expended for. development and as much more as
the gambling instinct may cause a man to expend in
equipment or road-building before he has actually
blocked out enough ore to pay for the money spent. The
royalty should not exceed 10% of the value of the ore at
the mine. At the risk of being ultra-conservative, we
would say that even in the interest of quick production,
and presumably of quick profit, the miner should not be-
gin the construction of a road to haul his product until
at least half the cost of the road is in sight in the form of
ore mined or exposed, and with more than one face in
good ore ; and that he should not begin the construction
of a mill until the whole price is in sight. The reason for
this last proviso is that the margin of operating profit on
concentrating ore is usually much smaller than on the
shipping grades and the other risks incident to the busi-
ness are large enough.

Characteristics and Surface Indications

Chrome ore is found associated with basic magnesian
rocks, usually serpentine. It is, therefore, a waste of
time to seek deposits in regions where no serpentine
exists. Wherever serpentine 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. It may be necessary to
dig shallow trenches cross-cutting 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 orebody.
Occasionally float cannot be traced to ore in place. This
is due to the fact that the orebody 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 plow is available, pick and

—14—

shovel work may take its place. The mining of float ore
frequently yields a high-grade product and may prove a
most profitable operation.

Miners are beginning to understand the characteristics
of these deposits. There are, however, manj^ new ones

lif^^^^-^-^aiTiJSirfi* %*wrai..

VAUGHN CHROME MINE. FROM THIS DEPOSIT WAS
COLLECTED 1200 TONS OF FLOAT CHROME

being worked by those less experienced, who make errors
in estimating the possible tonnage.

In many cases the miner considers he is opening an
orebody occurring in more or less irregular veins, and
that the origin of the ore is similar to that of quartz
veins. Outcrops may be found for a distance of several
hundred feet, and in such alignment as to give the im-
pression that the deposits are continuous. The handy

—15—

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pencil is then put to work to calculate that the average
width of the orebody is, say, 11 ft., the 'vein' can be
traced for 800 ft., and the ore ought to persist at least
20 ft. below the surface, giving, therefore, a total of
176,000 cu. ft., which, at 10 cu. ft. per ton, makes 17,600
tons of ore. This amount is then offered for sale.

O'UtC-r-OJo

Flo cut

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f<fclJ>|:,>»*^.

SECTION OF SERPENTINE HILL SHOWING IRREGULAR OREBODIES

Chromite does not occur in veins. In a few cases long
narrow lenses are observed extending 100 ft. or more
along the surface, and a few feet wide. The depth of the
orebody may be five feet or it may be 50 or more. This
can be determined only by development work; this
usually involves mining the ore, which, of course, necessi-
tates following the orebody.

—18—

Shape of Deposits. The irregular shape of chrome
deposits often presents puzzling problems. Figure 4 is
an illustration of the peculiar shape of one deposit. The
section extends through a serpentine hill containing
chrome. The lower deposit may be entirely disconnected
from the upper. In such a case the lower deposit might
not be found after the upper had been exhausted.
"When a deposit 'pinches out', a good rule to follow is to
dig a little further before abandoning the mine. Under
no circumstances should a 'stringer', a small ore-shoot,
be left unexplored in the face of the working. While it
may not pay to mine so small a shoot, dig it out, as it
may lead to another lens. We have followed this rule,
and have been handsomely rewarded for so doing.

Origin. To understand why estimates of chrome ore
cannot be prepared in the manner stated, it is necessary
to know something about its origin. When two sub-
stances, one of wiiich is more soluble than the other, are
dissolved in water, and the water is then evaporated, the
least soluble substance will crystallize out first. During
the period when the earth's crust was forming, chrome
was in solution, 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
crystallize from the magmatic 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 it is found, it seems probable that it
settled to lower depths during its aggregation. If this
be accepted as correct, the question arises, 'How did it
reach the surface?' Folding, faulting, and weathering
are the forces responsible for its exposure at the surface.

In Fig. 1 the lens of ore is shown in its normal position
on cooling; later folding resulted in the mass assuming
the position shown in Fig. 2 ; dynamic agencies, followed
by erosion, resulted in the condition seen in Fig. 3.
The dotted lines indicate the former position of the

—19—

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Fig. 5

rome \jk

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rocks that concealed the deposit as shown in Fig. 1 and
2. The dark portion represents the consolidated mass
of ore, surrounded by smaller bodies and segregated

—20—

particles, which, attracted toward the main orebody, did
not reach it because the progress was impeded by gradual
solidification of the magma to form solid rock.

All chrome miners are familiar with the gradual in-
crease in the amount of waste-rock in their ore as the
limits of their deposits are reached. Occasionally a de-
posit is found in which the line between the ore and wall-
rock is distinct, sometimes separated by 'gouge' or
'miner's talc'. When no chrome ore is found in the
wall-rock immediately adjoining the orebody, and gouge
is present, it may indicate that the original wall-rock
has been removed by displacement. The ore along the
wall may be fluted or grooved, and if the disturbance
has been sufficient, the orebody may be coarsely frac-
tured, or even so finely crushed as to make it friable,
that is, capable of being disintegrated by compression in
the hand. Otherwise, if no chrome is present in the
wall-rock, it may be due to earlier genetic causes. Some
magmas were undoubtedly more fluid than others, just
as some smelter slags run freely while others are so slug-
gish that they freeze readily at the tuyeres. In a partic-
ularly fluid magma there would be flow-currents just as
there are in water, these tending to carry away chromite
particles which had not yet been consolidated with the
main mass of chromite. For this reason I conclude that
the largest deposits of chrome were probably formed in
magmas relatively free from flow currents. Chrome ore
is always found in basic-igneous rocks, such as peridotite
or its altered form, serpentine. This is probably because
chromium is more soluble in basic than in acid magmas.

Distribution op Chrome in Deposits. All parts of
chrome deposits are not of equal grade. The question
has been asked, 'What may be expected to be the highest
grade?' In most deposits the ore near the walls or the
bottom is less pure than that in the main orebody. How-
ever, there is much variation ; and there is no rule to fol-
low. This irregularity probably results from minor in-
fluences during the period of formation. The principal
impurity is not necessarily silica; it may be iron, mag-
nesia, or alumina. If iron be present as magnetite, the
ore may be heavy and black, and may appear to the eye

—21—

. to be high-grade, yet actually low in chromic oxide.
Some good ore is found with a film of magnesium car-
bonate, or silicate, so that it is white in appearance, and
such ore has been condemned for that reason, because it
was considered to contain too much silica. It is impor-
tant to remember this: You cannot make an optical
analysis of chrome ore.

Field Determination of Chromite. Familiarize
yourself with the appearance of typical chrome ore.
Scratch a piece of the suspected ore with a knife, deep
enough to penetrate any surface film of foreign material.
If the streak is dark-brown, the material may be chrome.
If the prospector will provide himself with a spirit
lamp, two inches of platinum wire fused into the end of
a short glass tube, and an ounce of borax, he can make a
fair determination. The operation is as follows: Crush
a small piece of the ore to a powder; bend a small loop
at the end of the platinum wire; heat the wire in the
flame, and dip it in the borax. Some borax will stick to
the loop. Melt this in the flame, and continue dipping
in the powdered borax and melting it until the loop has
become filled with a bead of colorless borax-glass. Heat
the bead to redness, and, while hot, place it against the
crushed ore until a few particles adhere to the bead.
Hold this in the flame until the particles are entirely
dissolved in the borax, allow it to cool, and then the
bead, if chromium is present, will have a bright green
color. Having determined that chromium is present,
send the sample to a reputable chemist and ask him to
determine the amount of chromic oxide and silica. The
ore-buyer must know the percentages of these two ma-
terials before he can go further.

Minerals Mistaken for Chromite. Magnetite, or
magnetic iron ore, is frequently mistaken for chrome
ore. It is dense black, highly magnetic, and of about
the same weight as chromite. It is much harder, how-
ever, and can be scratched with a pocket-knife only with
difficulty, and it does not show the brown streak. It may
be distinguished also by crushing to the size of a pea.
If it can be picked up by a magnet it is not chromite.

Hematite, another ore of iron, is sometimes mistaken

—22—

for chromite. It is usually softer, and has a reddish
brown streak, quite different from that of chromite.

Homblende-picrite, a rock that is dark-green to black,
and quite heavy, is frequently found in chrome dis-
tricts. Hornblende may be similar in appearance. The
simple way to distinguish these rocks from chromite is
to scratch them with a pocket-knife ; the streak is grayish
to greenish-white.

Methods of Financing Operations. The prospector
finding a chrome deposit usually needs financial help to
develop it and put the ore on the cars. Ore placed on
railroad cars is as good as cash, for the owner can at once
get payment for the shipment, as explained in the sec-
tion on marketing. Prior to that time, however, one of
two methods is commonly employed. The owner of the
deposit may seek a partner who, for an interest in the
mine ranging from 25 to 75%, will furnish the neces-
sary funds. Whether such an interest should be 25%
or more may be determined by the visible profit to be
made, and by the ability of the prospector as a trader.
Funds are usually required to build roads to make the
ore available for shipment, and sometimes for sled-trails
or pack-trails which may be used for a part, if not all, of
the distance. "When the ore in sight is small, and this is
usually the case, the prospector should be satisfied to
start operations on a small scale, purchasing only such
picks, shovels, and drills as are necessary to extract
enough ore for the first carload. When that has been
done, the shipment, if the ore is a fair grade, will provide
$2000 or more as working capital, with which to expand
the work. To secure funds enough to buy hoists, cable-
ways, or other elaborate machinery, will necessitate the
spending of time in promotion that should be used in
mining. Financing small operations as corporate enter-
prises, and selling stock to get funds, is usually unsuc-
cessful and is not to be recommended.

Several of the larger purchasers of chrome ore are
willing to loan money to operators on contracts for the
output of the mine. The ore available must, of course,
justify the amount of the loan, which may be as much as
a quarter to a half of the value of the ore developed.

—23—

It is also necessary to know that the money loaned will
be used in mining, building roads, in providing neces-
sary equipment or improvements, and that the amount
is sufficient to start shipments by rail. The contract for
ore is made usually at a price slightly below the market
price, as the lender is taking a large risk while the miner,
of course, will reap all the profit. The reputation of
the miner for honesty and ability must be taken into con-
sideration in making such loans. At this point a word
as to fair play will be in order. A considerable number
of the loans made in the manner outlined above has been
lost because of duplicity and bad faith. Litigation fol-
lows and the mine ceases production. The United States
government, in these critical times, cannot permit pro-
duction to cease for such reasons as these, and the owner
who becomes involved in these disputes, causing the
cessation of production, is little better than a traitor.
Honest difference of opinion may sometimes occur, but
when this happens, don't rush to the lawyers with your
trouble. Sit down on a log with the 'other fellow' and
meet him half way in a fair discussion. If the difference
of opinion has no honest foundation, and would prevent
production, the facts should be reported to the U. S.
Department of Justice, for the Government will not
permit chrome deposits to remain idle if it can be pre-
vented.

Markets, Selling Conditions, Future
Prices. The following schedule of prices was pub-
lished in the 'Engineering & Mining Journal' on June
8, 1918, and is stated to be the schedule of a large
purchaser, f.o.b. cars at stations on California and
Oregon main line railroads.

Cr,03

%

30

Price
Per Unit

fO.85

0 90

Cr^Oa
%
40

Price
Per Unit
f 1 30

31

41

1 325

32

0 95

42

43

1 35

33

1.00

1 375

34

1.05

44

. • . . 1 40

35

1 10

45

1 425

36

1 15

46

1 45

37

1.20

47

1 475

38

1.25

48 and upward

1 50

39

1.276

Another large purchaser gives the schedule below
—24—

which is somewhat different. In each case, the prices
were effective on June 1, 1918, and are, of course, not
fixed for any specified period.

30

Price
Per Unit

»0.65

0 73

CroOa
%
41

Price
Per Unit
$1.33

31

42

1.34

33

0.79

43

1.36

33

0 86

44

1.38

34

0 93

45

1.40

35

1 00

46

1.42

36

1.10

1 20

47

1 44

37

48

1.46

38

1 25

49

1.48

39

1.275

50

1.50

Contracts. Contracts for ore are made for periods
ranging from one month to two years, most of the buyers
preferring, it is believed, to limit their contracts to about
six months. A fixed schedule of prices is provided in the
contract, and such prices remain effective during the
term of the contract. The amount of ore to be delivered
by the miner is sometimes specified, but, as it is difficult
to estimate the probable output of a deposit, it is prefer-
able that the contract should call for the entire produc-
tion, providing, if the purchaser prefers, a maximum
amount to be shipped.

Contracts should specify :
(a) Situation and name of mine.
(5) Length of time the contract is to run.

(c) "When deliveries are to start.

(d) Amount of ore to be sold.

(e) Price.

(/) Railroad station where the ore is to be loaded.
(g) Method of payment.

(h) How sampling of the shipment is to be done.
(i) Name of chemist whose analysis shall determine
the price.
A satisfactory form of contract is as follows:

(Town) State

Date

John Smith agrees to sell to John Doe Company and

John Doe Company agrees to buy tons of

chrome ore mined or to be mined from deposits situated

, to be delivered on cars at

at prices and terms as follows:

—25—

Price:

$ per unit for ore containing- 30% chromic oxide.

9 per unit for ore containing- 31% chromic oxide.

$ per unit for ore containing- 33% chromic oxide.

3 per unit for ore containing 33% chromic oxide.

$ per unit for ore containing 34% chromic oxide,

$ per unit for ore containing: 35% chromic oxide.

$ per unit for ore containing 36% chromic oxide.

$ per unit for ore containing 37% chromic oxide.

$ per unit for ore containing 38% chromic oxide.

$ per unit for ore containing 39% chromic oxide.

9 per unit for ore containing 40% chromic oxide.

$ per unit for ore containing 41% chromic oxide.

3 per unit for ore containing 42% chromic oxide.

$ per unit for ore containing 43% chromic oxide.

9 per unit for ore containing 44% chromic oxide.

9 per unit for ore containing 45% chromic oxide.

$ per unit for ore containing 46% chromic oxide.

$ per unit for ore containing 47% chromic oxide.

$ per unit for ore containing 48% chromic oxide.

9 per unit for ore containing 49% chromic oxide.

9 per unit for ore containing 50% chromic oxide.

If the silica content should exceed ....%, ....c.
per ton for eaeh one per cent of silica in excess of
said .... % shall be deducted, and buyer may reject, at
his option, any ore containing more than .... % silica.
No ore shall contain less than .... % chromic oxide.

Terms :

Payment in full .„ , ^ , ,.

. s -n J. £ or^ry, will be made upon presentation

(or) Payment of 80% ^ f

at Bank at of sight

draft and bill of lading showing certified railroad

weights, with invoice and certificate of analysis by

attached thereto. If any balance shall

remain due, this shall be paid within ten (10) days

from receipt of car at destination and completion of

sampling and analysis. Sampling by the John Doe Co.

Railroad weights shall govern all settlements.

Shipments :

Shipments will be started within days from

date hereof, and completed days thereafter. All

cars to be shipped to John Doe Company,

This contract is made subject to such conditions,
terms, and price, as may in the future be determined
by the United States Government.

(Signature)

(Signature)

John Doe Company.
By

—26--

How TO Make Shipments. Be certain that you have
40 tons, or more, of ore at the railroad switch before
asking the local railroad agent to deliver a car. Gon-
dolas are usually more convenient for loading, although
box-cars may be used if gondolas are not available.
When the car is spotted, load it promptly. A penalty is
charged by the railway company if the car is not loaded
within the time allowed. This may be 48 hours, but
shippers should load in less time than this. It is of great
importance in carrying out our war program to have
cars loaded and shipped with great speed. Load the
cars to their capacity whenever possible. The local rail-
road agent will tell you the maximum capacity of the
car. The capacity printed on the side of the car is not
the maximum capacity. When the car is loaded, notify
the railroad agent that the car is released for shipment.
The next step is to secure a bill-of-lading. Shipments
should be made on an 'order bill-of-lading.' Remem-
ber that the consignee shown in the bill-of-lading owns
the ore. A shipper should ship the ore to the destination
agreed with the purchaser, but should ship it to himself.
On the back of the 'order bill-of-lading' is a space pro-
vided for endorsements. The bill-of-lading should then
be endorsed, as in the case of a bank check. The en-
dorsement should read:

"Deliver to the order of John Doe Company.

John Smith.''

A copy of the face of an order bill-of-lading is given
on page 16.

Do not surrender the bill-of-lading until your receive
payment for the shipment.

Settlements are based on the railroad weights, and
this the railroad company will deliver through its local
agent. These weights should be noted by the railroad
agent on the face of the bill-of-lading, or on a separate
certificate of weight furnished by him. Arrangements
are usually made with some local bank so that the ship-
per can present to that bank his bill-of-lading, showing
the railroad weights, and his certificate of analysis, in
exchange for which he receives cash.

Some purchasers pay but 80 or 90% at the time the

—27—

shipment is made, the balance being paid on receipt of
the car at its destination or as soon thereafter as the
car has been sampled and analyzed. If the shipper
accepts such terms, he must not be disappointed if his
final settlement is delayed for a long period. Freight
moves slowly, and the shipment may be caught in em-
bargoes.

Specifications for Marketable Ore. Ore containing
28% or more of chromic oxide is saleable. If the silica
content exceeds 8%, a penalty of 25c. per ton for each
1% of silica over 8% is sometimes charged, and a maxi-
mum of 12% may be allowable. If the ore contains
more than 12% silica and the chromic oxide content is
fairly high, then the silica is sometimes permitted to ruii
up to 15% or more. Special arrangement with pur-
chasers must be made in such cases.

Occasionally, though rarely, low-grade ore may con-
tain too much iron to be saleable. There is no fixed
limit for iron, and most contracts make no mention of
the iron content, but iron in excess of 18 or 20% is not
desirable.

Methods of Marketing. The sale of ore to brokers,
dealers, and middle-men is not encouraged. Consumers
of chrome ore are willing to buy direct from the pro-
ducer, and the producer should not be compelled to divide
his profit with middle-men. Many dealers and brokers
are without financial responsibility, and some are lacking
in honesty. The miner and shipper have suffered so
much loss from transactions with them, that a warning
should not be necessary.

A list of some of the consumers follows:
American Refractories Co., Pittsburgh, Pa., and Mer-
chants National Bank Bldg., San Francisco.
Binney & Smith, 81 Fulton St., New York, N. Y.
California Chrome Co., Kohl Bldg., San Francisco, Calif.
Carnegie Steel Co., Pittsburgh, Pa.
Colorado Fuel & Iron Co., Denver, Colo.
Crucible Steel Co. of America, Pittsburgh, Pa.
A. C. Daft, Oliver Bldg., Pittsburgh, Pa.
Electro-Metallurgical Co., Niagara Falls, N. Y.
Harbison-Walker Refractories Co., Pittsburgh, Pa.

—28—

E. J. Lavino & Co., Bullitt Bldg., Philadelphia, Pa.
Lukins Iron & Steel Co., Seattle, Wash.
Metal & Thermit Corporation, 120 Broadway, New York.
Mutual Chemical Co., 55 John St., New York, N. Y.
Noble Electric Steel Co., 995 Market St., San Francisco,

Calif.
Otis Steel Co., Cleveland, Ohio.
Pacific Coast & Steel Co., San Francisco, Calif.
Pacific Coast & Steel Co., Seattle, Wash.
Pacific Electro Metals Co., Balboa Bldg., San Francisco,

Calif.
Frank Samuel, Harrison Bldg., Philadelphia, Pa.
Sawyer Tanning Co., Napa, Calif.
The Sherwin-Williams Co., Cleveland, Ohio.
St. Louis Refractories Co., Title Guaranty Bldg., St.

Louis, Mo.
The Ferro Alloy Co., 603 Symes Bldg., Denver, Colo.
The National Electrolytic Co., Niagara Falls, N. Y.
Youngstown Steel & Tube Co., Youngstown, Pa.

The above list is supplied by the United States Geo-
logical Survey, and, while doubtless not complete, con-
tains all the names of which the Survey has a record.

Some of the above concerns maintain representatives
on the Pacific Coast with whom direct contact may
be had.

Present and Future Markets. If chrome ore were
plentiful enough to supply the demand, there would be
used in the United States in 1918, between 150,000 and
200,000 tons. Because of our inability to produce this
amount, the consumption has been restricted to some
extent by Governmental action. The use of chrome ore
by several industries has been reduced in this way, and
f erro-chrome, an allay made from chrome ore, may be
used at present only in Government work. This will
reduce the demand to some extent. More chrome will
be required, however, than can be produced. The ques-
tion is constantly being asked, 'How long will these
prices prevail?* It is not believed that there will be a
substantial decrease in price as long as the War con-
tinues. How long this may be is a matter of conjecture.

—29—

Sampling and Analysis of Chromite

By ABBOT A. HANKS

Preparation of Samples. The sample sent to the
assayer, if it represents either a shipment or a lot of ore
extracted for shipment, should be taken so as to repre-
sent what it is intended to sample. It should weigh 40
to 60 lb., and contain no single piece larger than an egg.
When this sample reaches the laboratory it should all
be crushed through a rock breaker, set to give a one-half
inch product. The rock-breaker product should be
thoroughly mixed and cut down with a riffle, a Jones
divider, or similar sampler, to one-quarter of its original
size. This quarter (10 to 12 lb.) should be put through
laboratory rolls, set to give a product of 12 to 16-mesh.
This roll-product should again be cut down to a sample
of about one pound. The whole of this one-pound sample
should be pulverized in a disc-grinder or similar ma-
chine to pass 100 or 150-mesh. Before making the
analysis the pulp should be dried at 212 °F. to constant
weight.

Chromium

The analysis of chrome ore may be separated into the
following operations:

Fusion in an iron cnicible with sodium peroxide.

Dissolving the melt in water; filtering and making
acid with sulphuric acid.

Adding an excess of ferrous ammonium sulphate and
titrating with standard potassium permanganate solu-
tion.

The standard method is described in the following
text-books :

' ' Technical Methods of Ore Analysis, ' ' by A. H. Low.

''Standard Methods of Chemical Analysis," by W. W.
Scott.

''Principles of Quantitative Analysis," by W. C. Bias-
dale.

Weigh out I gram of 100 to 150-mesh product; place
in a 20-cc. iron crucible; add 8 gm. sodium peroxide
and mix thoroughly with a small glass rod; cover and

—30—

slowly fuse over a Bunsen burner by slowly rotating
over the flame for about five minutes; when complete,
decomposition of the ore will result. When partly
cool, transfer the crucible and the melt to a 400-cc.
beaker containing 150 cc. to 200 cc. water. When
action ceases, rinse the crucible and the cover, then boil
the solution at least five minutes, then dilute to 350 cc.
with hot water. When partly cool, filter and wash thor-
oughly with hot water. Dissolve the precipitate with
dilute hydrochloric acid to determine if the fusion was
complete. If not, start a new portion. Cool the filtrate,
transfer to a 1000-cc. beaker and dilute to 500 cc. with
cold water, and add 25 cc. sulphuric acid (2 to 1) ; add
50 cc. standard ferrous ammonium sulphate solution,
from an automatic pipette, to the solution in the beaker
and then titrate w^ith standard potassium permanganate
solution. Standardization is accomplished by weighing
J gm. of c,p. potassium chromate into a 1000-cc. beaker,
dissolve in cold water, and make acid as above and pro-
ceed as explained; 50 cc. of the ferrous ammonium sul-
phate- solution is titrated at least once each day by the
potassium permanganate to determine their relative
strength.

Potassium chromate equals 39.135% CraOg.

Ferrous ammonium sulphate solution contains 100 gm.
ferrous ammonium sulphate crystals and 20 cc. sulphuric
acid per litre.

Potassium permanganate solution contains 6.0 gm.
c.p. KMn04 per litre.

1 gm. potassium chromite equals 26.25 cc. KMn04.

69.45
26.25

43.20

86.40/ ^ ff V^^ CQuals 0.0045296 g^rams Cr.,03 equals value of 1 cc. KMnOi
06.4

Silica

One-half gram of ore is fused as above; dissolve in
50 cc. water; rinse off the crucible and the cover; make
acid with hydrochloric acid, and take to dryness twice
as for silica determinations. Complete as usual for
silica.

—31—

The Determination of Chromium in Chromite

The following rapid method is in use at the Berkeley
Experiment Station of the U. S. Bureau of Mines :

The ore should be ground to 100-mesh. Weigh out
0.5 gm. sample and brush into a 20-cc. spun-iron crucible
in which has previously been placed 4 to 5 gm. of fresh
NaaOa (technical grade is satisfactory). Mix well with
a glass rod, cover with a little NasOs and fuse at a low-
red heat. After the charge has melted it should remain
in the molten condition for five minutes. Allow the
crucible to cool, place in a 600-cc. beaker of pyrex or
other low-expansion glass or in a large casserole; add
water and digest until the fused mass has disintegrated,
after which remove and rinse the crucible. Boil for 10
minutes to decompose the NaoOo. Without filtering,
neutralize the solution with 1-4 HgSO^ or 1-1 HCl and
add 25 to 30 cc. excess. Dilute to approximately 400 cc,
cool and titrate with a standard solution (about 0.2 N)
of FeS04. Add a slight excess of FeSO^ solution, as
shown by spot-plate tests with a 1% solution of
K3Fe(CN)6, and finish the determination by back-titra-
tion with standard K2Cr207 solution. The FeS04 solu-
tion may be added rapidly without great care, as the
approximate end-point is readily recognized by the
color-change of the solution. With a little practice two
or three spot-tests should be sufficient to determine the
exact end-point.

Notes: The quickness of this method is due largely to
the omission of filtration before acidifying the dissolved
fusion. Manganese is practically the only interfering sub-
stance found in Western ores, and when this is present
filtration is necessary.

The initial alkaline solution containing the precipitate in-
clines to bump on boiling. A few chips of fresh unglazed
porcelain or a stirring-rod with roughened end, placed
opposite one of the points where the beaker makes contact
with the hot plate, minimizes this difficulty.

The standard FeS04 solution is prepared by dissolving 56
to 60 gm. FeS04-7H,0 in about 800 cc. distilled H.O, to
which has been added 100 cc. concentrated HoSO^. After
cooling, the solution is diluted to one litre. The 0.2 N
KoCr,07 solution may be made by dissolving 9.806 gm. c.p.
K.CraOT in one litre. The FeSO, solution may be standard-
ized with a standard KMnOi solution based on Bureau of
Standards sodium oxalate or against the KoCraOr solution,
provided this was made from a salt of known purity.

One cubic centimetre of 0.1 N solution is equivalent to
0.001733 gm. Cr, or 0.002532 gm. CrA-

—32—

YC" 15033

^^

3873G2

UNIVERSITY OF CALIFORNIA LIBRARY