TIN.

By FRANK L. HESS.

PRODUCTION.

The only tin ore produced in this country during the year 1908 was a few tons of stream tin sluiced from gravels in Seward Peninsula, Alaska, as described more fully in the following paragraphs.

Alaska. The American Tin Mining Company produced a few tons of stream tin from Buck Creek. The ore, which was taken out while assessment work was being done, carried 69 per cent of tin, and was shipped to Hamburg, Germany, for sale.

Buck Creek is in Seward Peninsula, about 20 miles east of Cape Prince of Wales. It is a short creek, only about 2 miles in length, and has a comparatively small drainage basin. The snowfall of the winter of 1907-8 is said to have been light and the following summer dry, so that water for sluicing was not plentiful.

The tin-bearing gravels are comparatively shallow, from 3 to 10 feet deep, and the tin content is relatively high, 28 pounds or more per cubic yard. The stream tin is derived from cassiterite occurring in small quartz stringers and larger veins in the slate country rock, and, in much less quantity, from tin-bearing quartz porphyries in the hills at the head of the creek. The principal accompanying heavy minerals are pyrite and arsenopyrite, which oxidize, leaving only iron oxides in the gravels, so that the stream tin is of excellent quality.

The Bartels Tin Mining Company, which began prospecting in 1903, continued work on Cape Mountain, near Tin City, 5 miles southeast of Cape Prince of Wales. The company has a number of shafts and tunnels. The tin occurs in its mine as impregnation veins in granite.

The United States-Alaska Tin Mining Company continued driving a prospect tunnel, which was begun in the winter of 1905-6, to cut a vein found higher up on Cape Mountain, on which a 35-foot shaft had been sunk. The tunnel was 421 feet in at the close of the year. No geologist of the United States Geological Survey has been able to examine the ore in the United States-Alaska Tin Mining Company's shaft, owing to water in the shaft. Near the shaft cassiterite is found in large quartz blocks. At other places on the mountain stringers of cassiterite nearly an inch thick have been found in the limestone débris.

Crim, Randt & O'Brien, just before the close of the season, washed a small quantity of stream tin from the gravels along Cas

siterite Creek, a branch of Lost River, about 30 miles southeast of Cape Prince of Wales. They did some further prospecting upon their tin deposits, but no lode tin was produced. In the course of their prospecting a wolframite deposit was found, which is reported as carrying 30 per cent of wolframite through 3 feet. The tin deposits in this locality occur in greatly altered quartz porphyry dikes cutting limestone and showing much replacement by fluorite. The cassiterite is evidently later than the dikes. The dikes carry also wolframite and small quantities of scheelite, molybdenite, topaz, axinite, fluorite, and other minerals. On the same claims cassiterite occurs also in quartz veins cutting the limestone. A mile farther up the creek it occurs in a dike composed largely of danburite and brown tourmaline.

Prospectors did some work on Brooks Mountain close to the head of Lost River during the summer, but no finds of tin have been reported. Adolph Knopf, of the Survey, discovered on Brooks Mountain two new tin-boron minerals in 1907, to which he gave the names of paigeite and hulseite. They are not at present of economic importance. Paigeite was also found on Ears Mountain.

North Carolina and South Carolina.-No work is known to have been done in the Carolina field during 1908. The tin-bearing area lies on both sides of the North Carolina-South Carolina line, in Cherokee County, S. C., and in Gaston and Lincoln counties, N. C. Cassiterite occurs as an original constituent of pegmatite dikes cutting gneisses and schists.

South Dakota.-At Tinton, in the northern Black Hills, the Tinton Company remodeled its mill and expects to mine tin ore during 1909. At Hill City, in the southern Black Hills, the Gertie Tin Mining and Milling Company was also engaged in remodeling its mill during 1908, with the hope of doing active mining in 1909.

The Black Metal Mining Company holds tungsten (wolframite) claims near Hill City that carry a considerable percentage of light colored cassiterite in quartz veins. These veins are in places more than a foot in width, and here and there contain handsome intergrowths of cassiterite, wolframite, and quartz. A considerable amount of development work was done on these claims during the year. No other operations on tin claims of the region, except annual assessment work, are known to have been carried on.

In the Black Hills cassiterite occurs as an original constituent of pegmatite dikes in shoots, about the regularity of which there is doubt. Cassiterite occurs also in quartz veins, which are probably a late if not a final phase of granitic emanation. Many other minerals accompany the cassiterite at various places in the Black Hills, but topaz and axinite are unknown and fluorspar is rarely found.

Washington. Neither development work nor production during 1908 has been reported from the tin deposits 12 miles south of Spokane, Wash. At this place also cassiterite occurs in pegmatite and is considered by A. J. Collier, who investigated the occurrence for the United States Geological Survey, to be probably an original mineral. It is accompanied by scheelite and wolframite.

Texas. The Florella Mining Company, which has tin deposits in the Franklin Mountains 15 miles north of El Paso, did some development work during the year, but marketed no ore. Seven veins have

been found upon its property, and the company reported a considerable amount of ore on the dumps. Placer tin has been found in the gulches near the veins. The deposits are replacement veins in granite and carry some wolframite with the cassiterite.

P. H. Parker, Streeter, Mason County, Tex., reported the discovery in 1908 of cassiterite near that place, both as stream tin and in place, the latter apparently in granite. Streeter is in the western part of the "Llano region," an area of crystalline rocks forming an island in the younger sedimentary formations of central Texas. White topaz and quartz penetrated by rutile crystals accompany the cassiterite. The occurrence is apparently more of geologic than of commercial interest.

TESTS FOR TIN ORE.

The simplest and easiest test for cassiterite is to place the mineral in dilute hydrochloric or sulphuric acid with granulated, sheet, or shot zinc. The zinc and the acid cause a rapid evolution of hydrogen, which takes the oxygen from the tin and leaves a coating of the metal upon the fragment tested. Hydrochloric acid and granulated zinc are best to use, as the evolution of hydrogen is very rapid and the zinc particles being small can be made to touch the specimen at many points and thus bring more of the hydrogen in contact with the tin-oxide molecules. The reaction is 4H+ SnO,= Sn+2H2O.

2

The metallic coating has a dull gray, somewhat leady appearance as formed, but it may be made lustrous by rubbing with a soft cloth or the hand. In the latter case the familiar disagreeable odor given when tin is rubbed on the flesh is obtained.

This excellent method may be used upon specimens which it is desired not to injure, such as crystals or other choice pieces. However, the smooth surfaces of stream-polished wood-tin are roughened, owing to the impurities contained in the mineral, though the surfaces of ordinary crystalline cassiterite are not noticeably affected. After the test is made the metallic tin coating can be removed by immersing the piece in dilute hydrochloric, sulphuric, or nitric acid. A better-known and often-used test, though one not so readily made, is the blowpipe test. The mineral supposed to be cassiterite is pulverized, and when so treated should yield a light-colored powder, unless mixed with iron oxides, in which case the powder will be reddish or brownish. A small portion of the powder is mixed with twice its bulk of pulverized charcoal and three times its bulk of sodium bicarbonate (ordinary baking or washing soda). The three substances are thoroughly mixed, and a portion the size of a pea is moistened and placed in a hollow in a piece of charcoal. On application of a reducing blowpipe flame tin is readily reduced in small globules, which are easily distinguished from the flux. After cooling the metallic globules may be separated from the soda and will be malleable. If large enough they will give the disagreeable tin odor when rubbed between the fingers, and will give a white precipitate when treated with concentrated nitric acid. They are soluble in hydrochloric acid, and no precipitate forms when the solution is cold. These reactions with acids differentiate the metal from lead.

PRODUCTION OF TIN IN FOREIGN COUNTRIES.

At the time of writing (June, 1909) it is not possible to obtain the figures of production for 1908 of all the tin-producing countries, but as shown by exports the following table, compiled by C. Mayer, secretary of the New York Metal Exchange, gives the approximate output for the year:

Supply of tin in 1907 and 1908, in short tons.

From this table it is evident that, in spite of what are in many places considered low prices, there was a large increase in the total production of tin, and that the supply for 1908 was the largest year's supply in the history of tin mining. Australia and China are the only countries that showed a decrease. In the latter case a decrease of exports is not surprising, as it is ordinarily only in years. of high prices that tin is drawn into the world's trade from Chinese sources. Little is known of the Chinese tin deposits.

The available figures showing the output of tin for 1908 are as follows:

Production of tin and tin ore in various countries in 1908, in short tons.

aThird annual statement of the trade and shipping of the colonies and territories forming the South African Customs Union, Cape Town, 1909.

Letter from P. M. O'Connor, for Director of Geological Survey of Transvaal, April 19, 1909. Of this total the Transvaal produced 1,426 tons, valued at $487,706.

c Statement of F. J. B. Dykes, Senior Warden of Mines, Federated Malay States, quoted in Min. Jour., London, vol. 85, 1909, p. 324. This tonnage paid a duty of $5,334,010.

The progress of the mineral industry of Tasmania for the quarters ending June 30 and December 31, 1908. Hobart, 1908 and 1909.

Letter from E. F. Pittman, Under Secretary for Mines, New South Wales, dated May 3, 1909. Tin ingots from imported ores were also produced to the amount of 1,153 tons, valued at $664,136.

7 Letter from I. Cohen, for Secretary of Mines, dated April 28, 1909.

Letter from A. Gibb Maitland, Government Geologist, dated April 19, 1909.

Min. Jour., London, vol. 84, 1909, p. 233.

i Queensland Government Mining Journal, vol. 10, 1909, p. 175.

Letter from P. Zezi, l'inspittore superiore capo del corpo reale delle miniere, Rome, May 15, 1909.

* Report of the Singkep Tin Company for year ending June 30, 1908, translated and quoted in Min. Jour., London, vol. 84, 1908, p. 686.

Winslow, Alfred A., Daily Cons. and Trade Repts., Washington, June 11, 1909, p 2.

Advance statement of mineral production of India by the Director of the Geological Survey of India, June 10, 1909. nValue from Bull. Internat. Union Am. Republics, July, 1909, p. 37.

IMPORTS.

a

During the year 1908 the United States imported for consumption 41,267 short tons of pig tin, valued as entered at $23,923,560, an average of 28.986 cents per pound. During 1908, as given by C. Mayer in the Annual Statistical Report of the New York Metal Exchange, the year's average price was 29.42. According to the American Metal Market and Daily Iron and Steel Report, it was 29.54 cents per pound. The agreement between these figures is as close as can be expected on an article which has a fluctuating price, and when it is also considered that the average price for the importation is exact as far as the invoice figures may be depended upon, while the market figures are an approximation.

The imports of tin into the United States since 1901 have been as follows:

Tin imported and entered for consumption in the United States, 1901–1908, in short tons.

The imports of 1907 and 1908 were remarkably close in quantity, only 10 tons more being imported in 1908 than in 1907; the difference in value, however, was very striking, being $8,150,703, or about 25 per cent, less in 1908 than in 1907 for almost precisely the same quantity.

PRICES DURING 1908.

In 1907 prices reached 443 cents per pound in May, and fluctuated considerably, especially during the first half of the year, but later they dropped and became somewhat steadier toward the end of the year, which closed with tin at 274 cents per pound.

In 1908, as shown by the Annual Statistical Report of the New York Metal Exchange, tin opened at 26.625 cents per pound, averaging 27.35 cents during January. The highest price during the year, 32.275 cents, was toward the end of April, and the lowest, 26.25 cents, was in the beginning of January. Metal Statistics, p. 69, gives the lowest price as 26.45 and the highest as 32.75, with an average for the year of 29.54 cents per pound. As a whole, the tin markets for the year were steady, compared with those of recent years.

RECOVERED TIN.

The recovery of tin from scrap, dross, type metal, babbit and other friction metals, bronze, etc., is growing, and especially is attention being given to saving tin from scrap, old cans, and similar waste.

The tin in tin plate, when exposed to the weather, slowly oxidizes, and the oxide, a brittle, hard, colorless substance, falls off as an imperceptible dust and is dissipated. When this happens the tin is lost for all time, so far as further use is concerned. The color of rusting tin

a Metal Statistics, 1909, p. 72.