Chapter XVII: TIN

BY JAMES M. HILL[140]

[140] The writer hereby expresses his thanks to Adolph Knopf, of the
United States Geological Survey, and R. R. Horner, of the United
States Bureau of Mines, for their assistance in the preparation of
this article.

USES OF TIN

Tin, ordinarily considered one of the minor metals, is nevertheless a metal of prime importance in the world’s present state of development. In 1913 the value of the world’s output of tin was $131,000,000, which was greater than the value of the world’s output of either lead or zinc. Without tin it is very doubtful if the present methods of food packing and distribution could have been accomplished. The principal use of tin is in the manufacture of tin plate, from which are fabricated the so-called “tins” or “tin cans” that everyone knows. The second largest consumption of tin is for the alloys, solder and babbitt made with lead, and brass and bronzes made with copper. Minor amounts of tin are used for making fine metal tubing, tin foil, and collapsible tubes for packing such materials as dental and toilet creams, artists colors, etc. Tin is consumed by the makers of silk, principally to give weight and “rustle” to their product.

In 1917 the consumption of tin in the United States was approximately 93,000 tons,[141] of which 19,000 tons was recovered from scrap materials. Of the total consumption 31,000 short tons was used for making tin plate, 20,400 short tons for solder, 13,800 short tons for bearing metals, (babbitt, bronzes, etc.,), and 27,700 short tons for the many minor uses, items of which are 1,000 tons for the silk industry, 5,000 tons for foil, 4,000 tons for collapsible tubes, 3,000 tons for white metal.

[141] In this report the figures for tons refer to metric tons (2,204
pounds avoirdupois) unless otherwise stated, and are given in round
numbers because errors in statistics and in conversion do not warrant
closer figuring.

It is difficult to distinguish between the essential and the non-essential uses of tin in the industries. Surely tin plate is essential, yet some saving of tin containers was made during the war shortage by curtailing the use of tin and substituting paper and other substances for packages carrying non-perishable products. Solders, bearing metals, and bronzes are unquestionably essential, but variation in alloy specifications made possible, during the war period, a considerable saving of tin without detriment to the results. In fact some of the standards set under the emergency were superior to those used before. Aluminum foil is to some extent replacing tin foil, but no suitable substitutes have been found for tin in the manufacture of collapsible tubes, which are necessities.

GEOLOGICAL DISTRIBUTION

Over 70 per cent. of the tin produced in the world is won from placer deposits, although in the last few years the exploitation of tin-bearing lodes has become of considerable importance. Tin ores are intimately connected with siliceous igneous rocks. Practically all of the known lode deposits are either in or lie near siliceous igneous rocks such as granite, granite-porphyry, quartz-porphyry or monzonitic types. In Mexico and the United States unimportant tin deposits have been found in rhyolite. In only one or two places in the world are tin lodes known where siliceous igneous rocks do not show on the surface, and in these places geologic evidence points to the presence of granitic rocks at no great depth. In the world’s chief centers of tin production--the Malay Peninsula, Bolivia, Australia, Nigeria, Cornwall, and South Africa--the granitic rocks are everywhere in evidence, and the tin lodes are so closely related to these granites that there is no question of their origin.

Fluorine-bearing minerals such as fluorite and topaz, tourmaline, and the tungsten mineral, wolframite, are found in practically all tin deposits. Molybdenite and bismuth minerals are present in many tin deposits, though their distribution is not so general as that of the former minerals. Copper, lead, zinc, and iron sulphides, the latter often arsenical, are common in tin lodes, and quartz and feldspar are the chief gangue minerals.

It is generally accepted that the tin lodes were formed near the close of intrusive activity by the final differentiates of the acid magmas. These final solutions are notable for their pneumatolitic action and their ability to cause the profound change of granite to greisen and the formation of stanniferous pegmatite and quartz veins. Greisen, an alteration product of granite, consists of quartz, mica and varying amounts of topaz and tourmaline. It is commonly developed along fractures, and in favorable places large masses of rock may be greisenized.

Tin deposits are most often found as lodes, both fissure and pegmatitic, or stockworks, but some segregations are known. A peculiar pipe-like form of deposit is found at places in the Transvaal and Tasmania.

Generally tin deposits he close to the contact of intrusive and intruded rocks and are mainly found near the top of the intruding mass. It therefore follows that in deeply eroded granite masses the chance of finding lode tin deposits is smaller than where search is made in the tops of granitic intrusions. It has also been noted that deposits in intruded rocks generally lie where the dip of the intrusive contact is low and are rarely present along a steeply dipping intrusive contact.

Practically the sole ore mineral of tin is cassiterite (tin oxide), which carries 78.6 per cent. of the metal. Cassiterite is known commercially by various names, such as tinstone, black-oxide of tin, black tin, or, where it occurs in placers, stream tin. The tin concentrates from placer mining normally carry 60 to 75 per cent. metallic tin, 70 per cent. being a fair average. The concentrates from the mills treating Bolivian lode tin make a product called barilla that averages about 62 per cent. tin; the concentrates produced from lodes in Cornwall average about 65 per cent.; and from the lodes and placers of the Malay Peninsula carry about 72 per cent. tin.

In many parts of the world the lodes do not carry sufficient tin to be worked profitably. In Cornwall and in Tasmania, lodes carrying about 1 per cent. of tin are being mined; but in general a content of 1 to 2 per cent. tin is the lower limit for commercial lode mining. In Bolivia the tin lodes average 5 to 8 per cent. tin and some bodies of ore carrying as much as 40 per cent. tin have been opened. In the places where low-grade tin ores have been mined the by-products, principally arsenic and wolfram, have helped to pay expenses, and most of these mines are advantageously situated with respect to transportation and supplies. In the placers of the Malay Peninsula, including Banca and Billiton, and those of Australia, which are worked by dredges, the tin content ranges from one-half pound to as high as 3 pounds, but averages less than a pound of cassiterite to the cubic yard. Advantageous location and cheap labor make profitable exploitation possible.

GEOGRAPHICAL DISTRIBUTION

As will be seen from the map, Plate IX, tin deposits are found in every part of the world, though an inspection of Table 60 and figure 9 will show that the deposits within the British Empire are the most important sources of the world supply. Bolivia and the Dutch East Indies have been the chief producers of tin outside of the British Empire, though China and Siam are steadily gaining importance as tin producers.

=British Empire.=--The British Empire has tin deposits in England, Asia, Australia, and Africa. The largest production is from the deposits in the Malay Peninsula. The African deposits, those in Nigeria and the South African Union, yield the second largest output of the empire, the Australian deposits rank third, and the Cornwall deposits, formerly the largest producer of tin in the world, now rank fourth.

_Malay Peninsula._--The _Federated Malay States_ and the _British Protected Malay States_ occupy the southern end of the Malay Peninsula. This region, which is entirely British controlled, produced for many years one-half of the world’s output of tin, but in the last few years the output has declined steadily. The decline seems to be due to the exhaustion of the easily worked placer deposits, though in 1917 and 1918 an additional cause was the scarcity of labor.

TABLE 60.--WORLD’S OUTPUT OF METALLIC TIN, 1913-1918, IN METRIC TONS[142]

(Metal obtainable by smelting from concentrates)

----------------------+-------+-------+-------+-------+-------+-------
Country | 1913 | 1914 | 1915 | 1916 | 1917 | 1918
----------------------+-------+-------+-------+-------+-------+-------
Cornwall | 5,370| 5,140| 5,060| 4,770| 4,000| 4,000
Nigeria | 2,950| 4,590| 4,630| 5,150| 7,070| 7,000
Union of South Africa | 2,050| 2,000| 2,050| 1,900| 1,540| 1,500
Federated Malay States| 50,930| 49,820| 47,520| 44,570| 40,470| 37,970
British Protected | | | | | |
Malay States | 1,800| 2,700| 4,170| 4,450| 4,500| 4,500
Australia | 8,160| 5,520| 5,680| 5,550| 4,970| 4,900
+-------+-------+-------+-------+-------+-------
Total British Empire| 71,260| 69,770| 69,110| 66,390| 62,550| 59,870
Percentage world | | | | | |
total | 52.6 | 54.1 | 53.7 | 52. | 47. | 45.8
| | | | | |
Banca | 15,940| 14,630| 13,660| 14,460| 13,540| 11,000
Billiton and Singkep | 5,300| 6,090| 6,760| 6,780| 7,300| 9,200
+-------+-------+-------+-------+-------+-------
Total Dutch | 21,240| 20,720| 20,420| 21,240| 20,840| 20,200
Percentage world | | | | | |
total | 15.4 | 16.1 | 15.4 | 16.7 | 16. | 15.5
| | | | | |
China | 8,390| 7,120| 8,000| 7,630| 11,800| 12,000
Siam | 6,660| 6,740| 8,520| 8,960| 8,600| 8,600
Bolivia | 26,760| 22,360| 21,900| 21,330| 28,320| 28,000
Other countries | 1,400| 1,500| 1,500| 1,700| 1,800| 2,000
+-------+-------+-------+-------+-------+-------
Total other control | 43,210| 37,720| 39,920| 39,620| 50,520| 50,600
Percentage world | | | | | |
total | 32. | 29.8 | 30.9 | 31.3 | 38. | 38.7
+-------+-------+-------+-------+-------+-------
World total |135,710|128,210|129,450|127,250|133,910|130,670
----------------------+-------+-------+-------+-------+-------+-------

[142] KNOPF, A., “Tin in 1918,” U. S. Geological Survey, “Mineral
Resources of the United States in 1918.”

The largest tin-smelting center of the world is Singapore, where the Straits Trading Co., and the Eastern Smelting Co., both British owned, and a Chinese-owned smelter, have a combined capacity of 58,000 metric tons of metal a year.

A large number of the Malaysian mines are worked by Chinese, though much English and Australian capital is invested in tin mining companies in the Peninsula, and the financial control of the industry is in the hands of British subjects. Political control is exercised by a prohibitive export duty ($285 per ton) on all tin ore exported for treatment except to the Straits Settlements, United Kingdom, or Australia.

As will be seen from Table 60 the Federated Malay States produce much more tin than the Protected States. Practically all of the tin in the Peninsula is taken from placer deposits, some of which are still worked by hand methods, though part of the black tin is now being mined by dredges.

The backbone of the Malay Peninsula is composed of granite which is intrusive into limestone, shale, and quartzite. Tin has been found in place in practically all of the rock formations. Owing to the intense weathering and erosion of the tin-bearing formations great accumulations of detritus, more or less mixed with clay, all of which carry cassiterite, are found in almost all parts of the Peninsula. The original deposits are so softened by weathering that they can be worked by hydraulic methods.

The provinces of Perak, Selangor, Pahang, and Negri Sembilan, in the Federated Malay States, produce tin. The following table shows their relative importance.

TABLE 61.--PRODUCTION OF TIN IN THE FEDERATED MALAY STATES IN 1917

Metric tons
Perak 25,075
Selangor 10,595
Pahang 3,750
Negri Sembilan 1,055

In Negri Sembilan, quartz veins in decomposed pegmatite are worked by hydraulicking and the mixed tin-tungsten concentrate obtained is further separated by magnetic machines. The principal mines are near Titi and Seremban.

Pahang, on the eastern side of the mountains, has many widely scattered tin deposits, both lodes and placers. The chief workings at present are in the mountains near the Selangor boundary, at Bentong, Tras, and Machi. Some mining is also done at various places along the Kuantan River and its tributaries. Transportation is a serious item in working tin mines in Pahang.

Kuala Lumpur is the center of the more important tin-mining operations in Selangor. Both decomposed lode-stuff and gravels are being worked. Near Serendah soft greisenized granite is worked by monitors. Near Tanjong, Malim, and on the Kalumpang and Selangor rivers in the northern part of the state both gravels and decomposed vein materials are worked.

The Kinta district, in the State of Perak, is the most important tin-producing area in the Federated States. A structural valley eroded in soft limestones between granite ridges is the location of most of the workings. The valley is filled with clays and boulder clays carrying tin, and the present stream channels are also stanniferous. Mining is in progress around 15 or more settlements in this district; much of the mining is by open cuts and dredges, but some lode mining is done on pipes in limestones. Next in importance to Kinta is the Larut district, northwest of the former. Placer deposits are the chief source of tin in the district but lodes are worked at Selama and Blanda Mabok. In the south of Perak, at Bruseh, stockworks in schist are worked by hydraulicking, yielding about three-fourths of a pound to the cubic yard of material worked.

Development of the tin deposits in the _Protected Malay States_ has been hampered by transportation difficulties. Until recently the alluvial tin was won by crude native methods. The principal producing comes from the states of Johore, Kedah, Kelantan, Perlis, and Trengganu.

Near Setul, in the State of Perlis, peculiar gravel-filled caves in limestone have been mined for tin. Some of these caves have been followed for four or five miles. In the State of Trengganu, lode mining under European management is under way. The lodes seem to be decomposed stockworks in granite.

An insignificant amount of tin is mined from the beach deposits on the Island of Malacca, Straits Settlements. The tin was derived from schists intruded by granite in which there are many stanniferous veinlets.

_Africa._--As will be seen from Table 60, the principal production of tin in Africa is from _British Nigeria_. The district was worked by natives in the early days, but no important production was made until 1904, after the subjugation of the Emir of Bauchi. The production of Nigeria has grown steadily till it reached 8,500 tons of concentrates in 1917. Seemingly all of the mines are controlled by British capital and the exports have been largely to the smelters in England.

The alluvial deposits of Nigeria are in the valleys of the Bauchi Plateau. Soda granite and pegmatites, intrusive into older crystalline rocks, seem to be the source of the cassiterite that has been concentrated by the present streams. Sluicing is the principal mining method, though some deposits are suitable only for dredging. Tin is also known in northern Nigeria in the Ningi and Burra hills, and other localities. In southern Nigeria tin has been found near Akwa-Ibami, in the Uwet district.

The tin output of the _Union of South Africa_ is chiefly from the Waterberg-Zaaiplaats district, in the western Transvaal, a little tin being mined in Swaziland and the Cape province. The production has ranged from 2,950 tons to 3,450 tons of concentrate a year, most of which before the war went to England for smelting, but since 1915 to the Straits Settlements. A small smelter, rated at 250 tons a year, was built at Zaaiplaats in 1917; it is expected to supply the tin needed in South Africa.

The Waterberg district contains several tin fields. Tin ores are found in the Red Granite and Waterberg felsites, sandstones, and conglomerates. In the former the ores occur in pipes, in irregular bodies of altered granite, disseminated in the granite, in impregnations along fissures, and in pegmatites and quartz veins. In the Waterberg series the tin ores are in lodes, and in irregular lenses and pockets whose position is determined by fissures or bedding planes.

In the Potgietersrust district the principal mines are largely pipe deposits in the Red Granite. These pipes, which are very erratic in direction, range from a few inches to 20 feet in diameter; some have been followed for 3,000 feet. The filling material varies greatly, ranging from slightly altered granite to a greenish homogeneous rock; the outer zones are tourmaline-quartz rock. In the smaller pipes the cassiterite is fairly evenly distributed but in the larger pipes it occurs near the outer edges.

In the Nylstroom district the principal mines are working ore deposits in felsites and shales of the Lower Waterberg series. The deposits are brecciated country rock cemented by quartz, tourmaline, cassiterite, and fluorite.

The Warmbaths field includes several mines located along the junction of the Red Granite and the felsites. Tin is found in lodes in both types of rocks and some alluvial tin has been mined. In the Rooiberg field, the tin deposits are practically all in fissures in quartzite intruded by Red Granite. Tin occurs in the Red Granite 40 miles north of Pretoria.

In the Cape Province, near Kuils River, cassiterite is found disseminated in granite and in veins at the contact of granite and slates. Most of the small amount of tin won has been obtained from gravels derived from these deposits.

In northwestern _Swaziland_ alluvial deposits have been worked for a number of years, producing around 500 tons of concentrates a year. At Forbes Reef, schists and slates have been intruded by granite and tin lodes are found near the contact of the two formations.

Tin has been reported in placer deposits in the Winnebah district and in pegmatite dikes in the Mankofa and Mount Mankwadi districts of the _Gold Coast_. Tin has been found in placer concentrates from streams in _Nyasaland_. Tin deposits seemingly of little value have been found in the Enterprise district, east of Salisbury, and in the Ndanga district, east of Victoria, in _Rhodesia_. These deposits are stanniferous pegmatites which are found in schists near granite.

_Australia._--Tin is produced in the following provinces of Australia: Tasmania, Queensland, New South Wales, West Australia, Northern Territory, Victoria, named in the order of their importance. In 1907, the output of Tasmania was about 14,000 tons of concentrates, but production since then steadily declined until it became nearly stationary at 3,000 tons annually for the last few years, and it is believed that this output can be maintained for some time.

There are tin-smelting works at Launceston, in Tasmania; Woolwich, near Sydney, New South Wales; and Irvinebank, near Herberton, Queensland, capable of producing over 4,200 tons of metallic tin a year. Of recent years tin concentrate is being sent to the Straits Settlements (Singapore) for smelting. The exports of metallic tin from Australian ports in 1917 came to about 3,100 tons.

Practically all of the mining companies are controlled by Australian and English capital, and as the tin is smelted either locally or at Singapore the total Australian output can be considered as under the direct political and commercial control of England.

The total production of tin ore from _Tasmania_[143] from 1880 to 1918, inclusive, is stated to be approximately 128,200 tons.

[143] Tasmania, Report Secretary for Mines for the year ending
December 31, 1918, p. 46.

The most important tin mine is Mount Bischoff, 45 miles southwest of Emu Bay. The deposits, discovered in 1871, are credited with a total production of about 75,000 tons of tin ore. There are several deposits, soft altered quartz porphyries intrusive into schists. Topaz and cassiterite are disseminated in the porphyries, and veins carrying tin and wolframite, together with pyrite and arsenopyrite, are found both in the porphyry and schists.

The Shepherd and Murphy mine, near Middlesex, is in a zone of metamorphism at the contact of granite, intrusive into sandstone and quartzite. Tin, tungsten, and bismuth are produced from this ore. Placer tin deposits on the Ringarooma River (Derby district) supply about 1,000 tons of tin concentrates a year. The principal placer mines are the Pioneer and Briseis. Near Gladstone, placers and lode deposits carrying tin and tungsten are worked. At the Anchor mine, in the Blue Tier district, a tin-bearing granite averaging one-half per cent. tin is worked, but mining has not been profitable. The Renison Bell, Dreadnought-Boulder and Montana mines, in the North Dundas field, are in slates cut by dikes of quartz porphyry. Zinc, lead, and iron sulphides are important in the lodes. In the Heemskirt district, southwestern Tasmania, the tin deposits are in granite and in overlying slate and sandstone. At the Federation mine the ore is in a pipe measuring 25 by 15 feet at the surface, but contracting to only 1 by 5 feet at 115 feet down.

Tin was first produced in _Queensland_ in 1872, and the total output, including 1917, is estimated to be about 144,008 tons. The chief producing districts are Herberton, Cooktown, Chillagoe, near the port of Cairns; Stannhills, Kangaroo Hills, and Stanthorpe, the latter being near the New South Wales border. In the Herberton-Cooktown districts the tin occurs in greisenized granite intruded into slates, schists, and quartzite; bismuth and tungsten minerals are associated with it. Placer deposits are worked by hydraulicking, and in places the tin-bearing greisen is broken down by hydraulic giants. In the Stannhills field, near Croydon, cassiterite is found in veins in granite with galena, sphalerite, and chalcopyrite. The Kangaroo Hills, 100 miles south of Herberton, produces both lode and placer tin. In the Stanthorpe district most of the output is from placer deposits, some of which are buried under basalts.

Tin was first mined in _New South Wales_ in 1872, and the total production, including the output of 1917, is estimated at 84,230 tons of tin and 34,510 tons of tin concentrates.

The chief producing districts are the Vegetable Creek and Emmaville-Tingha-Inverell region, in the northeast near the Queensland border, and the Ardlethan district, 40 miles west of Temora, in the south. In the Emmaville-Inverell region the erosion of stanniferous greisenized granite, intrusive into slates, has resulted in a widespread distribution of tin placers, both in the present streams and in what are believed to be Tertiary stream beds that are now capped by lavas. The Vegetable Creek mines, near Emmaville, are typical of the older placer deposits. Since 1900, dredging has become important, and it is estimated that the dredge production up to 1917 was 18,854 tons of concentrates. Lode mining, although not as important, has been done in this district in pipes and stock works in granite; the typical fluorine-bearing gangue minerals are common, and tungsten, bismuth, copper, and lead minerals are found.

Tin was discovered in the Ardlethan district in 1912 in lodes in granite and schist. Molybdenum, bismuth, and tungsten are commonly associated with tin in the greisenized granite lodes. The Barrier district, in the western part of the province, has not been a large contributor, because of lack of water. Cassiterite is found in dikes of coarsely crystalline granite intrusive into greisen and mica schist.

In _West Australia_ the most important tin-producing districts are Greenbushes, near the southwest, and Pilbara, on the northwest, though there has been a very small recovery of tin in the Murchison goldfield, and Coolgardie. In the Greenbushes district cassiterite is found in pegmatite and quartz-tourmaline veins in granite, but the tin won is from stream deposits and from laterite. In the Pilbara field the alluvial tin has been derived from pegmatite dikes that cut granite and metamorphic rocks.

The production of tin in _Northern Territory_ has amounted to about 200 tons a year, most of it being obtained from pegmatitic deposits in granite in the vicinity of Burrundie.

A few tons of tin concentrates are saved each year in the operation of gold placers in the Northeastern and Gippsland divisions of _Victoria_.

_India._--The principal output of tin in India is from the Mergui and Tavoy districts, southern Lower Burma; Tharton and Amherst districts, northern Lower Burma; and the Southern Shan States. The production amounts to about 150 tons of metallic tin a year, and is sent to the Straits Settlements for smelting.

In the Mergui district cassiterite is found in alluvial deposits near granite hills, the granite being intrusive into sedimentary rocks of uncertain age. Tin ore is also found in pegmatite and quartz veins. In the Tavoy district tin is obtained as a by-product of wolfram mining. The deposits occur in pegmatite and quartz veins cutting granite and sedimentary rocks. In the Tharton district the tin-bearing alluvium is said to be rich and its development is awaited with interest. Production of tin began in 1912 from the deposits of Bawlake State, Karenni, Southern Shan States, and in 1917 these deposits were the chief producers in India.

_Cornwall._--In the extreme southwest of England is the famous Cornwall tin region, which includes the Camborne, St. Austell, and Liskeard districts, in Cornwall, and the Tavistock district, in Devon. The mines have produced about 8,000 tons of concentrates a year, but at present the output seems to be diminishing; in 1915 the production of metallic tin was approximately 5,000 tons, but in 1918 was only about 4,000 tons.

Tin mining in Cornwall dates back to prehistoric times. In the sixteenth century the mines produced about 700 tons of tin a year; the maximum output was reached in the period 1860 to 1890, when about 10,000 tons was produced annually. It is estimated that the total output of tin from this district is approximately 1,750,000 tons. The mining companies are without exception controlled by British capital.

The second largest tin-smelting capacity in the world is in the Cornwall district. The following companies, Williams Harvey & Co., Penpoll, Cornish Tin Smelting Co., Copper Pass, Redruth Tin Smelting Co., and the London Smelting Co. operate smelters having a combined output of approximately 31,100 tons of tin a year.

The tin deposits of Cornwall and Devon lie about five masses of granite, which are intruded into slates (killas) and greenstones. Quartz porphyry dikes are closely connected with the granite, and the tin lodes are found in both slates and granite, being particularly abundant near intrusive contacts with low dips. The principal lodes are wide zones of fissured rock that are tourmalinized, the less important fissures containing tin and gangue minerals. Copper and tungsten minerals are produced from these lodes, and arsenic is an important by-product of smelting. The lodes in slates are as a rule richer in copper than in the granite, and in depth the lodes contain a larger proportion of tin than nearer the surface. The mines about the Camborne granite mass yield about 85 per cent. of the tin mined, those about the Lands End granite mass 12 per cent., and the mines about St. Austell, Bodmin Moor, and Dartmoor about 1 per cent. each.

Practically all of the tin produced in recent years has been from lodes, but placer tin was mined near St. Austell. The lodes have been worked to a depth of 3,000 feet, which seems to be about the greatest depth to which commercially profitable ore extends. As considerable ground above this level remains to be developed, the district should be productive for some time.

=Other Nations.=--Outside of the British Empire the principal tin deposits of the world are in Bolivia, the Dutch East Indies, China, and Siam, named in the order of their importance as producers in 1918. There are small outputs of tin from deposits in Japan, Spain, Portugal, and the United States, and tin deposits are known in Germany, Italy, Russia, Belgian-Congo, and Southwest Africa.

_Bolivia._--Practically all of the tin ore shipped from Bolivia is mined from lodes. Mining began late in the last century. Exports are in the form of barilla, a tin concentrate carrying 60 to 65 per cent. and averaging about 62 per cent. tin. The output has been steadily increasing, and since 1913 Bolivia has been the second largest producer of tin in the world. (See Table 60, and Figure 9). The majority of the companies working in Bolivia are controlled by Chilean or local capital, though a little English, French, Swiss, and German capital was invested in Bolivian tin mines before the war. Recently English and American capital has become interested in the deposits.

Prior to the war practically all of the barilla was sent to Germany and England to be smelted, but lately exports have been to the United States and England. A small Chilean-owned smelter, estimated capacity 900 tons a year, has recently been built at Arica to handle the concentrates from one of the larger mines.

There are four important tin-producing districts in east central Bolivia, in the provinces of Potosi, Oruro, and La Paz. The region lies on the high plateau (elevation, 12,000 feet) and the principal mines are near or in the mountains on the east of the pampa rather than in the western range of the Cordillera. Schists, slates, and quartzites have been intruded by acid igneous rocks, and the tin deposits are found in the granites, the quartz porphyries, and the sedimentary rocks near the contacts. The quartz veins are strong and carry between 3 and 8 per cent. tin in most of the productive mines, though some bodies of ore have carried as much as 40 per cent. tin. Some of the mines were worked for silver by the Spanish, but the silver ores seem to be limited to the upper zones, the lodes becoming relatively richer in tin at depth. Wolframite and bismuth are won as by-products at some of the mines. Pyrite, sphalerite, chalcopyrite, and galena are usually abundant in the tin ores, and tourmaline and fluorite are not uncommon.

The Bolivian deposits are of considerable future importance. Many mines and prospects, either through lack of knowledge or finances, have not been developed; the local management of most of the mines has been notoriously poor; and it is thought that with proper technical direction the output of tin can be greatly increased.

_Dutch East Indies._--On the islands of Banca, Billiton, and Singkep, south of the Malay Peninsula, are important tin mines. As will be seen from Table 60 the output of tin from these islands has been approximately 21,000 tons a year. Mining began on Banka about 1718, but the Billiton deposits were not worked until about 1860. The mines of Banka are worked by the government, but on Billiton and Singkep the deposits are leased by private concerns, mostly Dutch. At Banka the Dutch government operates smelters having a yearly capacity of 16,000 tons. The concentrates produced on Billiton and Singkep are in part sent to the Straits Settlements for treatment, but some are smelted locally.

Practically all of the tin mined in the Dutch East Indies is from placer deposits, some of which are alluvial. There is, however, a little lode mining on Billiton. The cassiterite was formed in greisenized granite and sediments, and the original deposits are similar to those of the Malay Peninsula. A little tungsten and gold are obtained as by-products of the tin mining.

_China._--Tin deposits in the Mengtze district, near Kochiu, Province of Yunnan, southeastern China, have been worked for many years. During recent years about 8,000 tons of tin have been exported, and it is known that considerable tin ore produced from these deposits is smelted locally, the metal being consumed in China. The exports go out through the French port of Haifong. The mining industry is entirely under Chinese control. Most of the tin ore is obtained by placer and open-cut methods from decomposed granitic and pegmatitic lodes which are found near the contact of granite that is intrusive into limestone. There are less important tin deposits in the Fuchuan and Tungchwan districts, the former producing a very pure metal.

The tin concentrates exported go mostly to Hong Kong and the Straits Settlements for treatment, so the Chinese tin output is more or less at the disposal of England.

_Siam._--In that part of Siam lying in the Malay Peninsula, tin deposits, similar in origin and occurrence to those in the British provinces, are being worked, and as shown by Table 60 are yearly becoming larger factors in the world’s output. The largest operations are near Renong and Tongkah, where dredging by British companies is active. The chief producing companies are Tongkah Harbor Tin Dredging Co., Tin Benbong, Bangnon Valley, Ronpibon Extended, Beebook Dredging Co., and Katoo Syndicate.

_Japan._--The tin-producing localities in Japan are near Kagoshima, Satsuma, on Kyushu Island; about 50 miles north of Kobe in Tajima province; and near Nayegi, Mino Province, near the center of the main island. Placer deposits near Nayegi have yielded some tin, seemingly derived from pegmatite dikes in granite. The Akinobe mine, in Tajima Province, was developed as a copper mine, but about 1912 tin and tungsten minerals were found in the ore. The veins are in slates and quartzites intruded by diorites. It is said that in 1917 about 40 tons of mixed tin-tungsten ores was produced daily. A small smelter at Ikuno handles the tin concentrates and produces about 250 tons of tin a year. The Susuijama mine, in Satsuma, produces tin from veins, in shales and sandstones, that also carry lead and zinc. Apparently the output is smelted and used locally.

_Spain._--In the provinces of Salamanca, Zamora, Orense, Pontevedra, and Coruña, northwest Spain, there are tin deposits. Lode deposits are found near the contact of granite intrusive into schists and gneisses, and placer deposits have been worked since ancient times. In 1913 about 6,700 tons of ore is said to have been produced, but since then the output has been around 100 tons a year.

_Portugal._--In Portugal, just south of the Spanish border, tin lodes in granite and slates have been found and placer deposits worked in the gravels adjacent to the lodes. The yearly output of these deposits is around 300 tons. It is reported that American capital is interested in some of the Portuguese tin and tungsten deposits.

_United States._--In the United States the domestic output is only nominal, being equivalent to 60 to 100 tons of tin a year. The productive deposits, placers worked by dredges, are in the York district of Seward Peninsula, _Alaska_. They occur near the contact of granite intrusive into limestones, in peculiar rocks of contact metamorphic origin.

Cassiterite has been mined from gravels derived from pegmatite dikes intrusive in pre-Cambrian rocks of the Black Hills near Tinton and Hill City, _South Dakota_, and various attempts have been made to mine the lode deposits. These deposits are of more scientific interest than commercial importance. A little stream tin has also been mined on the _North Carolina-South Carolina_ boundary near King’s Mountain, the cassiterite being an original constituent of pegmatite dikes intrusive into pre-Cambrian schists. At Irish Creek, Rockbridge County, _Virginia_, there are known stanniferous veins in coarse granites. In the Franklin Mountains 14 miles north of El Paso, _Texas_, quartz veins in granite carrying cassiterite were worked at one time but have not been productive of late. In the Temescal Mountains, Riverside County, _California_, small quartz veins carrying cassiterite are found in acid granitic rocks that are intrusive into metamorphosed sediments. Considerable work was done in this locality in the years 1880 to 1890, but the irregularity of the deposits and their low tin content do not hold much promise for future production.

Prior to the war the United States, although the largest consumer of tin in the world, produced practically no tin ore, and imported only metallic tin, having no smelters for treating tin ore. Since 1916 smelters have been erected by the American Smelting & Refining Co., and the Williams Harvey Corporation, their estimated capacity being 18,000 tons of tin a year. Presumably these smelters must rely largely on Bolivian concentrates.

_Germany-Austria._--Germany has produced practically no tin ores in recent years, though the country had a smelting industry, estimated at about 16,000 tons of tin a year, dependent on foreign ores. The normal imports of tin ore before the war were 17,000 to 18,000 metric tons a year, most of which came from Bolivia.

In the Erzgebirge, on the German-Austrian frontier, in the Altenberg-Zinnwald district, there was formerly some tin mining. The deposits, which are typical greisen lying near the tops and sides of bodies of granite intrusive into schists and gneisses, have made almost no production for several years and they are considered to be exhausted.

_Italy._--At Campiglia Marittima, Tuscany, iron and tin have been produced from veins in limestone and shale. The output is variable and cannot be relied upon.

_Russia._--In the former Empire of Russia tin has been found in the Trans-Baikal Province, Siberia, and in the Urals and Finland in European Russia. The Siberian deposits are placers in the basin of the Onon River. A German company was formed before the war to work lode tin deposits near Olovianoy, southwest of Nerchinsk, in the Urals. The Finnish deposits are at Pitkaranta, north of Lake Ladoga. The ores are a mixture of magnetite, cassiterite, and chalcopyrite, occurring in altered limestone and schist.

_Belgian Congo (Katanga)._--Alluvial tin derived from veins in granite and intruded sedimentary rocks has been found along Lualaba River and on Busanga Ridge. There are no records of production, but the field holds considerable promise.

_Southwest Africa._--Cassiterite occurs in pegmatite, intrusive into granite, in the Erongo Mountains east of Brandberg, and some placer tin deposits have been worked. On the whole the region does not seem to be particularly promising.

PROBABLE CHANGES IN KNOWN GEOGRAPHICAL DISTRIBUTION

It seems reasonably certain that _England_ is in a position to keep producing a large part of the world’s tin for some time, the lessening output from the Malaysian provinces being offset by the increased production of the African colonies. Both Cornwall and Australia, it is believed, will be able to maintain for a number of years a rather steady output of about the present size.

_Bolivia_ will doubtless be able to increase her output of tin, and probably both _Siam_ and _China_ can be expected to produce larger quantities in the future. Production of the _Dutch East Indies_ can probably be maintained at about its present rate for a number of years.

POLITICAL CONTROL

As will be seen from Table 62 and Figure 10, _Great Britain_ controls politically over 50 per cent. of the tin output of the world, in that her political influence is absolute in England, Africa, Australia, and all of her colonial possessions on the east side of the Indian Ocean; and there can be little doubt that the strong British policy with regard to the eastern colonies is also potent with respect to Siam and China.

_Holland_ controls the tin output of the East Indian island colonies, in which there are smelting works that seem capable of taking care of most of the ore mined. Holland consumes little tin herself and has approximately 16 per cent. of the world’s supply at her disposal. Prior to the war Holland was a large distributor of tin, but during the war tin from her colonies was sent direct to America and England, the largest consuming countries.

_China_ has a rather feeble political control of the output of the Yunnan tin mines, but as that part of her production which reaches the rest of the world is exported through French territory, largely through English middlemen, her actual control is not particularly great.

_Siam_ controls some important tin fields. The very strong British influence on the Malay Peninsula, coupled with the fact that the Siamese ore is smelted in the Straits Settlements, seems to indicate that British policy will largely dominate the tin-mining industry of Siam.

_Bolivia_, using little tin and producing nearly a quarter of the world’s output, is really the only considerable producer that can act more or less independently. Her mines are mostly controlled by Chilian-Bolivian capital and she has the world for a market. It would seem that Bolivian barilla might be smelted locally, but as Bolivia has no fuel, the tin smelting capacity of Bolivia amounts thus far to almost nothing. Her nearest market at present is the United States, but the future will show whether Bolivian ore will continue to be smelted in the United States, as during the past few years, or will be sent to England and Germany, as before the war.

The relation of political control of tin deposits and tin smelting is shown in the following table, and diagrammatically in Figure 10.

TABLE 62.--POLITICAL CONTROL OF TIN DEPOSITS AND SMELTERS BASED ON ESTIMATES FOR 1918

-------------+-------------+-------------+---------------+----------
| Control of | | Control of |
|tin deposits,| | tin smelters, |Percentage
|annual output|Percentage of|annual capacity| of world
Country |(metric tons)| world output| (metric tons) | capacity
-------------+-------------+-------------+---------------+----------
Great Britain| 59,900 | 45.5 | 88,300 | 57.3
Holland | 20,200 | 15.2 | 16,000 | 10.2
China | 12,000 | 9.3 | 12,000 | 7.4
Siam | 8,600 | 7.0 | |
Bolivia | 28,000 | 21.3 | 2,700 | 1.6
Germany | ... | ... | 16,000 | 10.2
France | ... | ... | 1,500 | 0.7
America | ... | ... | 18,000 | 12.4
All others | 2,000 | 1.7 | 500 | 0.2
+-------------+-------------+---------------+----------
Total | 130,700 | | 154,000 |
-------------+-------------+-------------+---------------+----------

COMMERCIAL CONTROL OF TIN MINES

British capital is the dominant controlling factor of approximately 57 per cent. of the world’s tin output, and through affiliations with capital of other countries it has a partial control of about 15 per cent. more. British capital is dominant in all of the British possessions and Siam, and through buying agencies practically controls the export tin from China. Bolivian tin mines are the only ones in the world in which British control is not strongly felt. The largest part of the Bolivian output is under the financial control of Chilean financiers, with local capital the next strongest factor. French and German money has been invested to a limited extent in Bolivian mines.

Recently the firm of Guggenheim Brothers, of New York, connected with the American tin-smelting industry, has acquired certain tin mines in Bolivia.

COMMERCIAL CONTROL OF TIN SMELTING

_British_ capital controls tin smelters with a yearly capacity of approximately 88,300 tons of tin a year. These are situated in England, Straits Settlements, and Australia. The tin deposits of undoubted British control can produce ore to furnish only 62,550 tons, so that England has a smelting capacity of 15,750 tons a year in excess of her supply.

The _Dutch_ control the smelters, having a capacity of 16,000 tons, of their East Indian colonies, but the annual output of ore from these colonies is equivalent to 20,200 tons of tin, so that an excess of 4,200 tons must be smelted elsewhere, and most of this goes to the smelters in the Straits Settlements, which are English owned.

_Chinese_ capital controls smelters that are seemingly capable of handling the entire output of China, about 12,000 tons of tin a year.

_American_ capital, since the war, has developed tin smelters in the United States and Bolivia, which have an annual capacity of 18,000 metric tons. This capacity is being enlarged and should be able shortly to take care of the entire Bolivian tin output, provided it receives the ore. But Chilean capital has built a smelter at Arica which could handle about 10 per cent. of the Bolivian output, and if this smelter is favored by Chilean mine owners the American smelters may find themselves short of ore.

_German_ capital is interested in tin smelters in Germany that have a producing capacity of 15,000 tons a year. All of the ore treated must be imported, but it hardly seems possible that much ore from outside sources can be expected for some time, as the smelting capacity of the world exceeds the output of the mines.

The tin-smelting capacity of the world is approximately 154,000 tons, whereas the world’s production of tin ore is equivalent to approximately 130,700 tons. It is evident that, unless greater production is forthcoming, some smelters will be idle, and it is a reasonable surmise that neither the British nor Dutch smelters will lack ore. The United States, owing to its favorable situation with respect to Bolivian supply, may hope to have a large part of its smelter capacity at work, though there is some question whether enough ore will be available to assure the maximum operation of the tin smelters in the United States.

POSITION OF THE TIN-CONSUMING COUNTRIES

_Great Britain_ produces more tin than she consumes and is therefore in a position to dispose of tin to the rest of the world. From a study of import and export tables it seems that England consumes about 20,000 tons of tin a year and that she imports about 55,000 tons and therefore has 35,000 tons for export. She is in position through her large political and commercial control of tin deposits and smelters to practically dictate the world’s tin policy.

The Dutch colonies produce about 16 per cent. of the world’s tin, and as _Holland_ is normally a very small consumer of tin, she has supplied a considerable part of the tin used in Germany and the United States.

Prior to the war a considerable tin-plate industry, dependent on foreign tin, was built up in southern Russia. The consumption was about 8,000 tons of tin a year, which was largely supplied by Great Britain, Holland, and Germany. If this industry is maintained Russia will still be under the necessity of importing considerable tin.

Tin users in _Germany_, who, before the war, apparently consumed about 22,000 tons of tin, must purchase all supplies from others. Before the war the principal supply of tin ore was Bolivia, and of metallic tin the Dutch East Indies. It seems reasonable that Germany’s supply of Bolivian ore may be curtailed in the future, as the United States is now in position to treat the ore, and freight rates should favor shipments of Bolivian barilla to the United States rather than to Germany. Whether the German tin-smelting industry will survive or not remains to be seen.

_France_ has a small tin-smelting industry, treating about 1,500 tons a year. The apparent consumption is about 7,000 tons of tin a year, most of which was formerly imported from British India, England, and the Dutch East Indies.

The _United States_ annually consumes over 80,000 tons of tin, including secondary metal, and produces from domestic ores about 100 tons. Prior to the war, metallic tin was obtained through England and Holland, as there were no tin smelters in this country. During the war there was established a tin-smelting industry, which is dependent entirely on foreign ore, most of which so far has come from Bolivia. The estimated capacity of tin smelters in America is about 18,000 tons a year or about 20 per cent. of the estimated yearly requirement. A combination of English, Bolivian and American capital is interested in one of these smelters, and also in Bolivian tin mines, and probably this smelter can be supplied. There is, however, considerable question whether the other smelters can obtain supplies of Bolivian ore. Certainly they will have competition from both English and German smelting concerns, which will be somewhat offset by cheaper freight to the United States than across the Atlantic. This difference is probably not large, and it would seem that if American smelters are to get Bolivian tin ore their charges must be low. A surer method of meeting their ore requirements would be to obtain financial control of enough ore deposits in Bolivia to supply the demand.

Evidently the United States must in the future, as in the past, import considerable quantities of tin from both Great Britain and Holland. It is to be hoped that the tin trade routes established during the war may be maintained and that American consumers will not have to pay the additional charges necessitated by Eastern tin going to Europe and back to the United States.