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.
[Illustration: PLATE IX.--Tin-producing localities of the world. By
James M. Hill.]
[Illustration: FIG. 9.--World production of tin, 1913-1918, in metric
tons.]
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.
[Illustration: FIG. 10.--Political control of tin deposits and tin
smelters, based on estimates for 1918.]
_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.