OTHER MINERALS
GOLD
Iron, in its usefulness to man, stands in a class to itself; but there
are dozens of other minerals that have their part in the comfort and
convenience of our daily life. Most of these, however, are found in
comparatively small quantities and have few uses.
The minerals which are in constant use by nearly all people and that are
found abundantly in the United States, are gold, silver, copper, lead,
zinc, and the elements used in manufacturing building materials.
Gold is valuable chiefly because it has been made the standard of money
value of the world. Africa produces one-third of the world's supply,
next come the United States and Australia, producing almost equal
amounts, Russia and Canada each produce a limited amount, and various
other countries together produce about one-sixteenth of the whole. (In
the statements of the gold supply of the United States the territory of
Alaska is included.)
Gold is not found alone but contained in quartz rock or sand. The method
of taking gold from the rock is first by blasting, and afterward
grinding the rock in a stamp mill, which reduces it to powder, after
which the gold is separated by refining processes. The gold which occurs
in the sand, gravel, or clay soil, is washed out. When done on a small
scale this is called "panning." The larger operations of this kind are
called "placer" and "dredge" mining. There is also a considerable amount
of gold obtained as a by-product from copper mining.
Generally speaking, quartz mines are in the mountains and placer mines
in the river valleys. Placer mining by powerful water pressure, called
hydraulic mining, destroys the banks, and also fills up the river beds
with masses of rock and gravel. Some of the large rivers of California
have been made unfit for steamboat traffic, and serious damage has been
done to the harbor of San Francisco. For this reason hydraulic placer
mining has been stopped by law. This has greatly lessened the gold
production of California.
In 1907, the United States produced $94,000,000 worth of gold. Of this,
Colorado produced more than any other state. Next in their order come
Alaska, California and Nevada. Each produced from $15,000,000 to
$20,000,000 worth. Together they furnished nearly four-fifths of the
entire supply. The remaining one-fifth comes from Utah, South Dakota,
Montana, Arizona, Idaho, and Oregon, with very small amounts from the
southeastern states, the two Carolinas and Georgia, New Mexico,
Washington, and Wyoming. South Dakota has the most profitable single
gold mine in the United States. It has produced nearly $60,000,000 in
gold, and is now turning out about $5,000,000 worth a year.
The United States has many unworked gold mines, "gold reserves" they are
called, whose value can not in any way be exactly estimated. The value
of the placer mines can be better judged than that of the lode or quartz
mines. The placer mines are chiefly in Alaska and California. These
mines may yield gold to the amount of a billion dollars. There are
lesser, but important resources of placer gold in Montana, Idaho, and
Oregon.
The placer gold mined in 1907 was valued at $24,000,000, and it is
thought that about this quantity can be supplied for a long time.
The amount of gold yielded in the reduction of copper ores was about
$5,500,000. It is probable that this amount will be gradually increased,
and can be relied on to last many years. From the lead ores a little
over $2,000,000 worth of gold was taken. This will probably slowly
decrease for the next ten or twenty years. From gold and silver-bearing
quartz mines $55,000,000 was taken.
No calculation can be made as to the amount of gold contained in quartz
mines. New discoveries are always probable and many new mines are opened
up each year, but their value can only be estimated as the work in them
progresses.
Just how long they will last nobody knows, but it would seem that their
decline is far off. The government report says, "Unless very important
new discoveries are made it is thought unlikely that the production of
gold in the United States will rise much above $110,000,000; nor is it
likely that it will sink below $60,000,000 within a long period of
years."
The amount of gold used in the United States is about equal to the
production. Nearly $80,000,000 is coined into money, and about half as
much is used in the arts,--that is, for jewelry, tableware, in
dentistry, in bookbinding, and various chemical processes. The quantity
used in the arts has doubled since 1900. In 1907 the stock of gold coin
in the United States, according to the Director of the Mint, was
$1,600,000,000, which is almost exactly one-fifth of the gold coin of
the world.
The production of gold is rapidly increasing. Since 1850 we have mined
three times as much gold as in all the previous time since the
discovery of America. Such rapid production greatly shortens the life of
the gold supply. When the gold fields of southern Africa were first
opened they were said to be inexhaustible; but they have been mined so
rapidly, and the supply has proved so far short of the first excited
estimates that experts say that the entire region will be almost
exhausted within twenty years. The loss of gold in mining and refining
is comparatively small. In extracting gold from the cheaper ores the
percentage of loss is large; but as only a small part of the gold is
gained in this way the total loss is relatively small. By other methods
ninety-five per cent. or more is saved. In many cases the loss is too
small to be considered.
Unlike other minerals little gold is destroyed by use. It is melted and
remelted, all scraps are used, even the sweepings from the mint and from
manufacturing goldsmiths' shops are saved and the gold used. The waste
of the world's gold and silver would be much greater but for the use of
paper money, bank checks, and notes. Their very general use keeps the
gold as a reserve, held in banks and storage vaults much of the time. If
it were in constant use, the continual rubbing together of the coins
would mean a no less steady, though slight, wearing away of their
surface. This is very noticeable in old silver coins, which are kept in
more constant circulation.
SILVER
The conditions in regard to silver are entirely different from those of
the other resources. The production of silver is not increasing, in
fact, the mining of silver alone is decreasing and the reason is not
because the supply is lessening, but because the price is too low to
make a larger working of the mines profitable, and the supply is kept
down to the level of the demand. A great number of silver mines have
been closed for the last few years. The production could be greatly
increased at any time to meet an increased demand.
The highest production was in 1902, but there have been only slight
changes since 1895; the production being a little less than 60,000,000
ounces, or about one-third of the world's supply--Mexico being the only
other great producer. In many countries with a small supply the output
is growing less each year on account of the low price, and the
difficulty of competing with the United States.
The states now producing the most silver are Colorado, Montana, and
Utah; each of these produces about one ounce out of every five ounces
mined. Most of the remainder was produced by Nevada, Idaho, Arizona, and
California.
Although nearly 60,000,000 ounces were mined in 1907 only one and a half
million ounces were mined for the sake of the silver alone. The rest was
obtained as a by-product in the mining of gold, lead, copper and zinc,
or, as is often the case, it was distinctively silver ore, but could not
be profitably mined unless some other ore could be obtained at the same
time.
The richer regions seem to have been exhausted, and as the process of
extracting the ore is expensive the lower grade ores will probably be
held for several years till prices advance. A great silver region has
recently been opened in northern Canada. This contains immense
quantities of very rich ore, and will probably keep the price down for
many years.
So the care and conservation of silver is not an important issue for the
people of the present generation. As silver is now obtained largely as a
by-product, there is almost no waste.
The United States sends considerably more than half of its silver to
other countries, principally to India and China, which use much silver
coin, but have little in the way of silver resources. The amount used at
home is divided between coinage and manufacture. The quantity coined
varies greatly from year to year, eight million ounces being about the
average. For manufacturing, jewelry, tableware, chemicals, etc., about
twenty million ounces, of which one-fifth is remelted silver, are used.
The demand for silver in manufacturing has doubled since 1898, and may
lead before many years to the reopening of the silver mines.
COPPER
The conditions of copper mining are exactly opposite from those of
silver. The Indians used almost no metal except copper, and for three
hundred years white men used the old Indian mines and refined the copper
by Indian methods. Better methods of mining copper and extracting it
from the ores have been employed for the last fifty years, but within a
dozen years the refining of copper has been revolutionized by electric
methods. An enormous amount has been produced, but production has been
kept down on account of the high prices. It is said that if the price
could be reduced one-half, ten times as much copper would be used. Most
of the uses of copper have arisen in the last twenty-five years. Its
greatest use is for electric wiring. Nothing can take its place, and the
use is increasing astonishingly.
Copper is used largely in alloys. Bronze is an alloy of copper and tin,
and its use has greatly increased in castings, fittings for buildings,
tablets, and statues.
A much more useful alloy is brass, made from copper and zinc. Brass is
very extensively used for parts of machinery, engines, automobiles, and
also for fittings for buildings. Sheet copper is used for sheathing for
ships, for boilers, and for various chemical processes carried on by
electricity or by acids. Very many of these processes have been
discovered within ten or fifteen years, and have largely increased the
uses for copper. One of the older uses of copper which is less common
now was for cooking utensils. Copper is used by the government for
coining one-cent pieces.
No single country compares at present with the United States in the
production of copper, but if reports be correct there is enough copper
in central Africa to supply the world for years to come. Next to the
United States, Spain mines the largest amount at present, and Japan
ranks next.
For many years the rate of increase was enormous. In 1845, 224,000
pounds were mined; in 1888, 226,000,000 pounds. Eight years later, in
1896, it had doubled; after another ten years, in 1906, it had doubled
that quantity, and reached 918,000,000 pounds. In 1890 we were using
three pounds of copper for every man, woman and child in the country.
And in 1907, six and one-half pounds.
Michigan, Montana, and Arizona produce the bulk of the copper. Utah,
California, Colorado, New Mexico, Wyoming, and Nevada each produce
copper in amounts ranging from the 66,000,000 pounds mined in Utah to
the 2,000,000 pounds mined in Nevada. It is probable that the use will
not increase so rapidly in the near future. Much old copper will be
remelted.
There are large areas of copper lands which are now classed as
"available" with copper at about its present price of thirteen cents a
pound. If the world production should grow so great as to cause a
decided drop in the price, much that is now considered available could
not be mined at a profit, and the copper supply from this country would
be greatly reduced. If, on the other hand, copper should rise to fifteen
or twenty cents or higher, the amount of available copper land would be
vastly increased. The report on the Conservation of Mineral Resources
says in effect: "The copper resources of the United States are believed
to be large enough to allow for a number of years for a demand
increasing at the rate of 30,000,000 pounds a year. Should this demand
continue for a long period the scarcity would be felt and result in a
rising price, which would open up a market for these low-grade ores and
also cause the use of other metals, like aluminum, to take the place of
copper whenever possible."
There is no great waste in the mining of copper, but in the extraction
of copper from the ore the waste is often as much as thirty per cent.,
and it is not easy to avoid this on account of the chemical changes that
take place.
LEAD
The United States produces about one-third of the lead in the world. The
remainder comes from Spain, where the production remains about the same
from year to year; from Germany, where in spite of higher prices
production is growing less; and from Australia and Mexico, in both of
which the supply is rapidly decreasing.
These facts show that the lead resources of the United States will be
drawn on heavily in the future. The production of the United States
increased from about 70,000 tons in 1880 to 365,000 tons seventeen years
later, and if continued the yearly production by 1920 will amount to
580,000 tons, or more than a billion pounds.
The principal lead-producing states are Missouri, Idaho, Utah, and
Colorado. In Missouri it is probable that the present rate of increase
could be kept up for at least fifty years. The other states could keep
up the present production for many years but could not greatly increase
it without exhausting the supply.
As with most mineral resources in the United States, it is only the
richest ores that are now drawn upon (except where lead is a by-product
extracted with some other ore). If prices would advance, so as to make
the low-grade ores profitable, the amount of our resources would be
greatly increased.
There is little waste in the mining or smelting of lead ores, and the
slag, the waste, is always ready to be used again. In the refining and
concentrating of lead the loss often amounts to as much as fifteen per
cent. or twenty per cent. The best way to prevent final loss is to store
all refuse until such time as the reworking becomes profitable.
Improvement in methods has been great in the last fifteen years but more
economical methods everywhere will be one of the necessities of the
future. We can see that the lead resources of the United States are not
large and that when our own supply is exhausted we can not turn to the
rest of the world.
The waste in mining is not large, and most of it can not be avoided at
present prices; so that for the conservation, which we see is so
important, we must turn to the uses of lead. The most necessary of these
is for lead pipes in plumbing. Another use is for war supplies, which
not only makes heavy drains on our stores of coal and iron, but also on
lead, which is much less plentiful.
One ton out of every three produced in the United States is used in the
manufacture of white lead and consumed as paint. This, of course, is
entirely lost, and it seems that some other material might be used,
instead of so valuable a mineral, especially when the resource is not
abundant. White lead is used more than any other substance for paint,
although zinc white has come into considerable use in the last few
years. No other nation uses lead paint to such an extent as does the
United States, partly because no other nation could afford so general a
use of such an expensive material, and partly because so many wooden
buildings are erected. By using brick, stone, or cement, of which we
have practically an unending supply, to take the place of wood, our
store of which is rapidly disappearing, we could avoid much of the drain
on our mineral resources which are used for paint.
As production and price advance a greater quantity of lead is remelted.
About 25,000 tons are returned to use each year.
ZINC
Zinc is a whitish metal. It is used in galvanizing iron to prevent its
rusting. It is used also in the manufacture of white paint, which
consumes about one ton out of every six tons mined. This, of course, is
permanently lost, but the price and its value as a resource is much
lower than lead. This takes more than half of the entire product. The
remainder of the output is about equally divided between brass and sheet
zinc. All these uses are extremely necessary and it is believed that the
production of zinc will rapidly increase for many years.
The United States is the largest producer, Germany ranks second. Large
amounts are mined in Australia, and very large deposits, entirely
undeveloped, are said to exist in Africa. In 1880, the United States
produced 23,000 tons of zinc; in 1907, 280,000 tons. This indicates the
rapid rate at which we are increasing our use of zinc.
If the same rate should continue, in 1920 we should be using 475,000
tons, or almost a billion pounds, and if zinc oxide should take the
place of white lead in painting to the extent that now seems probable,
the quantity would be still further increased.
Missouri is by far the heaviest producer of zinc, having a little more
than half of the output. New Jersey ranks next, then Colorado, Wisconsin
and Kansas. Some of the other western states each produce small amounts.
Most of the pure zinc ore is mined at a depth of from one hundred and
fifty to two hundred and fifty feet and occurs in sheets, but a large
part of the ore is a by-product obtained from the reduction of other
ores. In New Jersey the zinc alone is found in a single region, where it
was estimated a few years ago that there were eight million tons, of
which two and a half million tons have been mined since 1904. The zinc
in Missouri, Wisconsin and Kansas is found alone or underlying lead
deposits, while that of the western states is almost always found in
limestone, and is mixed with silver, copper, lead, and, more rarely,
gold. In these states there has been little attempt to discover zinc; in
fact, ores containing zinc have been rather shunned because of the
difficulty in extracting them.
It is thought that our resources of zinc, especially in the West, have
just begun to be developed, and that the supply, even at the present
rate of increase and at present prices, will last many years. However,
with increasing use for the product, we can not be sure of supplies for
more than a generation; and in view of the importance of zinc it becomes
necessary to inquire into its wastes.
In no mineral is the waste more startling than in zinc. In Missouri it
is necessary to leave supporting pillars as in coal mining. This can not
be remedied, as the use of timbers is too expensive, but it causes a
heavy loss. In the West, owing to the expensive treatment and shipment,
much of the low-grade ore is left in the ground. In refining the loss is
enormous, often as much as forty per cent. In order to produce zinc at a
low cost there must be a heavy loss of metal. Better plants and
equipment for refining, and the saving of all refuse for later use will
be necessary if we are to conserve the zinc supply for future
generations.
MISCELLANEOUS
The supplies of many of the materials used in buildings and bridges,
such as stone, gravel, clay, cement and lime are so great that they
appear inexhaustible, and need of care in their use is not so much to be
considered as is their development to take the place of other resources.
In the past they have not been used freely because wooden buildings have
been so much cheaper; but cement, concrete and brick are now
manufactured much more cheaply, on account of improved methods, while
the price of lumber has been increasing rapidly. Within the last ten
years, the value of cement manufactures has increased nearly six times.
In 1900 we used seventy pounds of cement for each person; in 1907, two
hundred and twenty-eight pounds. The value of brick and other products
made from clay has doubled in the same period and is now $160,000,000,
while the value of building-stone quarries is three times as great as it
was ten years ago. There are many reasons why these materials should
take the place of wood; as they are stronger, more durable, do not
require paint, and are so much less liable to loss by fire.
The waste of minerals used in building is due to improper and reckless
methods of taking them from the ground and preparing them for market and
in careless methods in manufacturing.
Of such minerals as quartz, grindstone, millstone, emery stone, mineral
paints, talc and salt, there seems to be enough to meet the needs of the
future as well as the present. Such supplies as sulphur, asphalt,
magnesia, borax, and asbestos, as well as coal and iron, are not very
plentiful. If used carelessly, they will be exhausted in a few years; if
wisely, they may be expected to last beyond the limits of the present
century.
Our supplies of quicksilver, antimony, graphite, mica, tin, nickel,
platinum, and many minerals less well known, as well as our petroleum,
natural gas, copper, gold, silver, lead, zinc, and phosphate rock will
be almost exhausted well within the present century unless large new
deposits are discovered.
REFERENCES
Report of National Conservation Commission.
The Conservation of Mineral Resources. U. S. Government Reports.
Report of the U. S. Geological Survey.
Production of Gold in 1908. U. S. Government Reports.
Production of Silver in 1908.
Production of Lead in 1908.
Production of Zinc in 1908.
Production of Structural Materials.
About twenty pamphlets on other minerals.