First, the amount of iron remaining in the ground is very uncertain. It may be more, or it may be less, than the present estimate.

Second, if the estimates are nearly correct, and if the present rate of increase continues, all the high-grade ores will be exhausted by the time the small boys of to-day are the business men of the nation.

Third, the best methods of reducing the drain on the supply are, (a) The use of old iron as a mixture; (b) Carrying a part of the freight by water to reduce the amount of iron required by the railroads; (c) The larger use of concrete and cement to take the place of steel in buildings; (d) Lessening the amount used for war; (e) The use of alloys.

This opens a large and promising field for invention. (f) More care in preserving articles made of iron. This is a practical thing for every person in our country to do. Every farm implement, or tool, that stands out in the rain or is left without shelter during the winter, every article carelessly lost or broken, has its part in making conditions worse. All that are well cared for help to make the iron supply last a little longer.

REFERENCES

Iron and Steel at Home and Abroad. (Andrew Carnegie.)

Conservation of Ores and Related Minerals. (Carnegie.) Report Governor's Conference.

Report National Conservation Commission.

Reports Geological Survey.

Mineral Resources of the U. S. in 1908. Advance chapters available.

CHAPTER VIII

OTHER MINERALS

GOLD

Iron, in its usefulness to man, stands in a cla.s.s 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 quant.i.ties 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 ma.s.ses 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 quant.i.ty 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 n.o.body 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 quant.i.ty 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 sc.r.a.ps 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 quant.i.ties 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, princ.i.p.ally 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 quant.i.ty 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 bra.s.s, made from copper and zinc. Bra.s.s 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 j.a.pan 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 quant.i.ty, 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 cla.s.sed 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.