PLATINUM.

By DAVID T. Day.

PRODUCTION.

The conditions of platinum production in the United States, where the metal is obtained as a by-product in placer gold mining, have not changed significantly in the last twelve months, although in one or two large mines in California apparatus modeled after that used in the investigations of black sands at the Portland Exposition in 1905 has been installed for greater economy in saving the platinum. The production in 1908 increased over that of 1907 from 357 ounces to 750 ounces. The total value was not proportionately as great, inasmuch as the price for ingot platinum declined from $25, at the close of 1907, to $18.20 in August, 1908, when a rise began, bringing the price to $24.50 in November, with a slight decline at the end of the year. The decline in price during the year may be attributed chiefly to stagnation in the manufacture of sulphuric acid and in other industries in which platinum is used.

Production of crude platinum in the United States, 1880-1900, and of refined platinum from domestic ores in 1901–1908, in troy ounces.

The chief variations in price up to 1901 have been due to the quality of the crude product. Since 1901 the average price for the refined metal has been given.

781

IMPORTS.

The imports of platinum from other countries, chiefly Russia, declined in 1907 and in 1908 both as to quantity and value, as shown in the table given below:

Platinum metals imported and entered for consumption in the United States, 1902-1908.

26.00

PRICES.

The following table gives the prices of ingot platinum per troy ounce at New York, by months, for the calendar years 1906, 1907, and 1908:

Prices of ingot platinum per troy ounce on the New York market in 1906, 1907, and 1908,

by months.

NOTES ON THE PLATINUM INDUSTRY.

UNITED STATES.

All of the platinum produced in the United States is recovered from placer mines in Oregon and California, which also produce gold. The bulk of the production of California comes from the dredges at Oroville, in Butte County, but small quantities are also recovered from Humboldt, Siskiyou, Trinity, Del Norte, Sacramento, and Calaveras counties. In Oregon small quantities are obtained from Coos, Curry, and Josephine counties. The platinum is usually panned from the black sand, but a small quantity is entangled with the amalgamated gold and is finally recovered in the refining operations at the mints. In 1908, 1,214 ounces of platinum were recovered at the mints, but only a small portion of this is derived from the placer gold, the bulk being obtained from scraps of various kinds, principally from dental work, which are sold to the mint.

The total production credited to California is 706 fine ounces, valued at $13,414; Oregon is credited with 44 fine ounces, valued at $836.

There was no production from the copper ores of Wyoming, which in places contain platinum. A new district in which platinum is reported to occur in primary ores, associated with copper and nickel, was discovered some years ago in southern Nevada. Howland Bancroft, of the United States Geological Survey, visited this region in 1909 and has furnished the following résumé of its geologic features:

PLATINUM IN SOUTHEASTERN NEVADA.

The district is located in Clark County, Nev., 16 miles from Bunkerville, at an elevation of 4,175 feet above sea level, about 45 miles by wagon road east of Moapa station on the Salt Lake route.

The country traversed on the way to the prospects is principally desert waste. About 4 miles west from the Key West property a capping of Paleozoic (?) limestone becomes quite prominent. This overlies the older gneiss and is separated from it by a limestone conglomerate which seems to occupy the uneven surface of the gneiss. The limestone is continuous up to within 2 miles of the properties examined, where it has been entirely eroded. Two miles west of the prospects the limestone can again be seen. The Key West mine has shipped one carload of ore. No shipment has been made from the Great Eastern.

On the Key West there is in all a little over 3,000 feet of development work. This includes 2 shafts, the main one being down 312 feet, 3 levels, winzes, and drifts. As the lower levels were under water, information upon the workings below the 120-foot level was given by S. W. Darling, superintendent of the Key West.

The Great Eastern has been developed by crosscuts only on 2 levels. In all there is some 600 feet of work done on the prospect.

The geology in the immediate vicinity of the prospects consists of coarse-grained gneisses, apparently of granitic origin, showing distinct gneissic structure. The prevalent direction of schistosity seems to be northeast with a very steep dip to the northwest. These rocks stand almost vertically and, with the accompanying jointing parallel to the shearing planes, form in places prominent ridges. Along these ridges can be seen distinctly the successive intrusions of various basic rocks with aplite and pegmatite, all of which are common to the region. The two latter intrusives are evidently later than the metamorphism of the region. The ore body is simply a very basic intrusive in the gneisses and differs mainly from the numerous dark-colored dikes found throughout the area in its large content of augite and olivine. The rock in which the values occur is a peridotite. The writer was informed that values are also obtained from a rock which appears to be a typical hornblendite or a very hornblendic phase of diorite. Assays will be made of the various rocks, and the results will be published later. In places the dikes evince the results of intense movement

and lead one to believe that the metallic elements of the rock have simply concentrated during metamorphism. The only metallic minerals visible in the unaltered dikes are the various sulphides of iron and copper.

The ore bodies proper occur in peridotite dikes which are exposed in several different places on the way from the Great Eastern property to the Key West, a distance of about 1 mile. The extent of outcrop upon the surface was generally 100 feet or more and varied in width from 10 to 50 feet. It is probable that these will be faulted in various places both laterally and vertically, as indicated by the fault in the Key West property and by the displacements seen in the country rock in the vicinity. The Key West and the Great Eastern are both located on similar dikes.

Both properties appear to be more valuable for their nickel or copper content than they are for their platinum. A series of assays of Key West ore made by H. E. Wood, of Denver, in 1900 shows an average of 3.9 per cent copper, 2.92 per cent nickel, 0.05 ounce gold, and a trace of silver for the sulphide ores. Whether Mr. Wood tested for platinum or not is uncertain. At any rate his returns do not indicate the presence of platinum. Mr. Trent, of Pioche, Nev., who examined the property in 1903, had some assays made at Stanford University which ran, according to his report, 1.7 per cent copper, 1.3 per cent nickel, and 0.05 ounce platinum."

Assays from the Great Eastern are stated to show 1.5 per cent copper, 0.9 per cent nickel, 0.25 ounce platinum.

If these properties were near a railroad, or if the ore could be treated on the ground, it is quite probable that they would be able to produce bullion. Under present conditions, however, working expenses would be very high. The Key West property has not been worked for six years.

RUSSIA.

The most reliable figures obtainable for the production of platinum in Russia are given in the following table:

Production of platinum in the Ural Mountains in the last few years, in troy ounces.

A valuable report has recently been published by Dr. W. Geibel on the conditions of mining in Russia, including a criticism of the statistics of production and a statement of the general conditions under which platinum is sold. An extended abstract from this report is given below:

DEPOSITS.

The oldest deposit of platinum is situated in the district of Nischne Tagilsk, below 58° north latitude, about 100 kilometers north of Yekaterinburg, the chief mining city of the Urals. The center of this district is Solowieffberg, the only place where platinum was found in place. The alluvial deposits of four streams, which have their source on its slopes, contain platinum; the total length of the platinum-bearing river beds amounts to 106 kilometers. Three of the streams flow toward the European slope, one to the Asiatic.

Tagilsk was for a long time the principal place of production, and up to the year 1891 produced 77 per cent of the total output of platinum. Since 1825 about 100 tons of platinum have been gotten out there. The beds are now pretty well exhausted and are surpassed in production by the northern districts; in late years they have not yielded more than one-fourth of the total production. The old tailings are now largely reworked. The platinum beds of the district are for the most part owned by

Prince Demidoff.

About 120 kilometers north of Nischne Tagilsk, on the Asiatic slope of the mountain range, lie, near together, the districts of Bissersk and Goroblagodat. Two rather large rivers, the Iss and the Wija, with numerous tributaries, contain platinum; at

a Estimated.

"Platin:" Private report by Dr. W. Geibel, Hanau, Germany.

their source lie three rock masses consisting of peridotite. The Iss and the Wija empty into the Tura, which for a little distance from the mouth of these tributaries also contains platinum. The total length of the alluvial beds worth washing is 130 kilometers. At present these two districts are the principal producers of platinum, their production amounting to about 70 per cent of the total output; but, in the opinion of the experts, with the present intensive exploitation on the Iss there are at work about 60 washeries, on the Wija 100-their wealth will be exhausted in about ten years. The most important beds in the district of Bissersk belong to Count Schuwaloff; those in the district of Goroblagodat to a French stock company, the Compagnie Industrielle du Platine.

The more northerly beds, situated in the district of Bogoslowsk, below 60° north latitude, are in process of development. The two old regions lie in the vicinity of the Ural railway, but Bogoslowsk is situated nearly 200 kilometers from it and was not opened to trade until 1906 by the building of a branch road. The production of this district so far is small; there is hope, however, that it will increase substantially. The northerly limit of platinum is not marked by this district. Its presence has been proved as far north as 62° north latitude. From there on to the Arctic Ocean stretches an unexplored, uninhabitated region for a distance of 600 kilometers. We know that the chain of eruptive rock stretches to the sea. When the inevitable exhaustion of the old beds takes place, the industry may be transferred to this region. Of course the cost of production will rise markedly.

METHODS OF EXTRACTION.

Platinum is obtained almost exclusively by placer methods. The overburden is taken off, and the platinum-bearing material is raised and carried to the washer on barrows. As running water is the principal requisite, the ore can be dressed only during the few summer months.

The separation of the platinum is more or less perfect, according to the kind of apparatus used. The simplest washing appliance is a hemispherical pan holding about 5 kilograms, in which, with the help of the running water, a small quantity of the material is washed by hand until only the heaviest particles-glittering grains of platinum together with chromite and magnetic iron-remain at the bottom. This pan is used principally for sampling. It is, however, used for the real extraction of the platinum in the unfortunately still very prevalent so-called "starateli" work. For the owner who can not or will not invest capital in machinery, the most convenient method of getting his treasure is to give permission to the little groups of workmen roaming about-the starateli-to work his property at their own expense; he then buys from them the platinum obtained at a stipulated low price. This method causes great wastefulness in mining. The laborers work only the very richest deposits, and these most imperfectly, with their primitive implements. They give up only a part of the platinum obtained, for traveling agents pay a somewhat higher price. The owners know this very well, but they can not prevent it; for any system of supervision would cost money, and so they content themselves with the profit that they can get without trouble.

The commonest apparatus for extraction on a large scale is the washer. It consists of a common wooden sluice as flat as possible and about 8 to 13 meters long, the bottom of which is suppled with numerous diagonal riffles, with a reservoir above and another below them. The platinum-bearing material is shoveled into the upper reservoir, stirred up by a powerful stream of water, and forced into the sluice, where the particles of metal settle in front of the riffles. In the lower settling basin the remaining platinum collects.

The sluice is operated for a period of twelve hours, then a clean-up is made from sluice and basin and concentrated on another smaller washer. The gold is extracted by amalgamation. By the best methods about one gram of the precious metal is recovered from a ton of sand, and we may safely assume that about 10 per cent of the platinum content is lost. At least as much more is stolen. The workmen are extremely skillful in stealing, even under strict surveillance.

The methods described are followed when the platinum deposit is in an old river bed or on the banks of a river. The present beds of these rivers also usually contain platinum, and to obtain this platinum other processes must be used. Up to a short time ago the only one in use was the "freeze out." This method consists in sinking a shaft in the frozen river bed and extracting the material that is worth washing.

Not until 1900 was the present method of extraction introduced-the floating dredge. This requires a larger business capital, but admits of far quicker operation. The dredge, or "draga," is run by steam power and can accomplish with a force of 30 workmen as much as 600 men can accomplish with washers. Its use is not now limited

87150-M R 1908, PT 1-50