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 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.