Bronze is an alloy consisting primarily of copper, commonly with about
12% tin and often with the addition of other metals (such as
aluminium, manganese, nickel or zinc) and sometimes non-metals or
metalloids such as arsenic, phosphorus or silicon. These additions
produce a range of alloys that may be harder than copper alone, or
have other useful properties, such as stiffness, ductility, or
The archeological period where bronze was the hardest metal in
widespread use is known as the
Bronze Age. The beginning of the Bronze
Age in Western
Eurasia and South
Asia is conventionally dated to the
mid-4th millennium BC, and to the early 2nd millennium BC in China;
everywhere it gradually spread across regions. The
Bronze Age was
followed by the
Iron Age starting from about 1300 BC and reaching most
Eurasia by about 500 BC, though bronze continued to be much more
widely used than it is in modern times.
Because historical pieces were often made of brasses (copper and zinc)
and bronzes with different compositions, modern museum and scholarly
descriptions of older objects increasingly use the more inclusive term
"copper alloy" instead.
2.1 Transition to iron
3 Technical information
3.1 Composition and alloys
3.3 Varieties of fitness
4.4 Musical instruments
4.5 Coins and medals
5 Image gallery
6 See also
8 External links
The word bronze (1730–40) is borrowed from French bronze (1511),
itself borrowed from Italian bronzo "bell metal, brass" (13th century)
Medieval Latin as bronzium) from either,
bróntion, back-formation from
Byzantine Greek brontēsíon (11th
century), perhaps from Brentḗsion ‘Brindisi’, reputed for its
bronze; or originally,
in its earliest form from Old Persian birinj, biranj (برنج)
"brass" (modern berenj), piring (پرنگ) "copper", from which
Serbo-Croatian pìrinač "brass", Georgian brinǰao
"bronze", Armenian płinj "copper".
A hoard of bronze socketed axes from the
Bronze Age found in modern
Germany. This was the top tool of the period, and also seems to have
been used as a store of value.
The discovery of bronze enabled people to create metal objects which
were harder and more durable than previously possible.
weapons, armor, and building materials such as decorative tiles were
harder and more durable than their stone and copper ("Chalcolithic")
predecessors. Initially, bronze was made out of copper and arsenic,
forming arsenic bronze, or from naturally or artificially mixed ores
of copper and arsenic, with the earliest artifacts so far known
coming from the
Iranian plateau in the 5th millennium BCE. It was
only later that tin was used, becoming the major non-copper ingredient
of bronze in the late 3rd millennium BC.
Tin bronze was superior to arsenic bronze in that the alloying process
could be more easily controlled, and the resulting alloy was stronger
and easier to cast. Also, unlike arsenic, metallic tin and fumes from
tin refining are not toxic. The earliest tin-alloy bronze dates to
4500 BCE in a
Vinča culture site in Pločnik (Serbia). Other
early examples date to the late 4th millennium BC in Egypt, Susa
(Iran) and some ancient sites in China,
Luristan (Iran) and
Mesopotamia (Iraq).
Ores of copper and the far rarer tin are not often found together
(exceptions include one ancient site in
Thailand and one in Iran), so
serious bronze work has always involved trade.
Tin sources and trade
in ancient times had a major influence on the development of cultures.
In Europe, a major source of tin was the British deposits of ore in
Cornwall, which were traded as far as
Phoenicia in the Eastern
In many parts of the world, large hoards of bronze artifacts are
found, suggesting that bronze also represented a store of value and an
indicator of social status. In Europe, large hoards of bronze tools,
typically socketed axes (illustrated above), are found, which mostly
show no signs of wear. With Chinese ritual bronzes, which are
documented in the inscriptions they carry and from other sources, the
case is very clear. These were made in enormous quantities for elite
burials, and also used by the living for ritual offerings.
Transition to iron
Though bronze is generally harder than wrought iron, with Vickers
hardness of 60–258 vs. 30–80, the
Bronze Age gave way to the
Iron Age after a serious disruption of the tin trade: the population
migrations of around 1200–1100 BC reduced the shipping of tin around
Mediterranean and from Britain, limiting supplies and raising
prices. As the art of working in iron improved, iron became
cheaper and improved in quality. As cultures advanced from
hand-wrought iron to machine-forged iron (typically made with trip
hammers powered by water), blacksmiths learned how to make steel.
Steel is stronger than bronze and holds a sharper edge longer.
Bronze was still used during the Iron Age, and has continued in use
for many purposes to the modern day.
Bronze bell with a visible crystallite structure.
Composition and alloys
There are many different bronze alloys, but typically modern bronze is
88% copper and 12% tin. Alpha bronze consists of the alpha solid
solution of tin in copper. Alpha bronze alloys of 4–5% tin are used
to make coins, springs, turbines and blades. Historical "bronzes" are
highly variable in composition, as most metalworkers probably used
whatever scrap was on hand; the metal of the 12th-century English
Gloucester Candlestick is bronze containing a mixture of copper, zinc,
tin, lead, nickel, iron, antimony, arsenic with an unusually large
amount of silver – between 22.5% in the base and 5.76% in the pan
below the candle. The proportions of this mixture suggests that the
candlestick was made from a hoard of old coins. The
Benin Bronzes are
in fact brass, and the Romanesque Baptismal font at St Bartholomew's
Church, Liège is described as both bronze and brass.
Bronze Age, two forms of bronze were commonly used: "classic
bronze", about 10% tin, was used in casting; and "mild bronze", about
6% tin, was hammered from ingots to make sheets. Bladed weapons were
mostly cast from classic bronze, while helmets and armor were hammered
from mild bronze.
Commercial bronze (90% copper and 10% zinc) and architectural bronze
(57% copper, 3% lead, 40% zinc) are more properly regarded as brass
alloys because they contain zinc as the main alloying ingredient. They
are commonly used in architectural applications.
Bismuth bronze is a bronze alloy with a composition of 52% copper, 30%
nickel, 12% zinc, 5% lead, and 1% bismuth. It is able to hold a good
polish and so is sometimes used in light reflectors and mirrors.
Plastic bronze is bronze containing a significant quantity of lead
which makes for improved plasticity possibly used by the ancient
Greeks in their ship construction.
Silicon bronze has a composition of Si: 2.80–3.80%, Mn:
0.50–1.30%, Fe: 0.80% max., Zn: 1.50% max., Pb: 0.05% max., Cu:
Other bronze alloys include aluminium bronze, phosphor bronze,
manganese bronze, bell metal, arsenical bronze, speculum metal and
Detail of the relief memorial to Cyprian Kamil Norwid, Wawel
Cathedral, Kraków, by Czesław Dźwigaj
Bronzes are typically very ductile alloys. By way of comparison, most
bronzes are considerably less brittle than cast iron. Typically bronze
only oxidizes superficially; once a copper oxide (eventually becoming
copper carbonate) layer is formed, the underlying metal is protected
from further corrosion. This can be seen on statues from the
Hellenistic period. However, if copper chlorides are formed, a
corrosion-mode called "bronze disease" will eventually completely
destroy it. Copper-based alloys have lower melting points than
steel or iron and are more readily produced from their constituent
metals. They are generally about 10 percent denser than steel,
although alloys using aluminium or silicon may be slightly less dense.
Bronze is a better conductor of heat and electricity than most steels.
The cost of copper-base alloys is generally higher than that of steels
but lower than that of nickel-base alloys.
Copper and its alloys have a huge variety of uses that reflect their
versatile physical, mechanical, and chemical properties. Some common
examples are the high electrical conductivity of pure copper,
low-friction properties of bearing bronze (bronze which has a high
lead content— 6–8%), resonant qualities of bell bronze (20% tin,
80% copper), and resistance to corrosion by seawater of several bronze
The melting point of bronze varies depending on the ratio of the alloy
components and is about 950 °C (1,742 °F).
usually nonmagnetic, but certain alloys containing iron or nickel may
have magnetic properties.
Varieties of fitness
Bronze, or bronze-like alloys and mixtures, were used for coins over a
Bronze was especially suitable for use in boat and ship
fittings prior to the wide employment of stainless steel owing to its
combination of toughness and resistance to salt water corrosion.
Bronze is still commonly used in ship propellers and submerged
In the 20th century, silicon was introduced as the primary alloying
element, creating an alloy with wide application in industry and the
major form used in contemporary statuary. Sculptors may prefer silicon
bronze because of the ready availability of silicon bronze brazing
rod, which allows colour-matched repair of defects in castings.
Aluminium is also used for the structural metal aluminium bronze.
It is also widely used for casting bronze sculptures. Many common
bronze alloys have the unusual and very desirable property of
expanding slightly just before they set, thus filling in the finest
details of a mould.
Bronze parts are tough and typically used for
bearings, clips, electrical connectors and springs.
Bronze also has very low friction against dissimilar metals, making it
important for cannons prior to modern tolerancing, where iron
cannonballs would otherwise stick in the barrel. It is still
widely used today for springs, bearings, bushings, automobile
transmission pilot bearings, and similar fittings, and is particularly
common in the bearings of small electric motors.
Phosphor bronze is
particularly suited to precision-grade bearings and springs. It is
also used in guitar and piano strings.
Unlike steel, bronze struck against a hard surface will not generate
sparks, so it (along with beryllium copper) is used to make hammers,
mallets, wrenches and other durable tools to be used in explosive
atmospheres or in the presence of flammable vapors.
Bronze is used to
make bronze wool for woodworking applications where steel wool would
Various kinds of bronze are used in many different industrial
Phosphor bronze is used for ships' propellers, musical instruments,
and electrical contacts. Bearings are often made of bronze for its
friction properties. It can be filled with oil to make the proprietary
Oilite and similar material for bearings.
Aluminium bronze is very
hard and wear-resistant, and is used for bearings and machine tool
Fragment of a bronze statue, Vatican Museums, Rome
The Assyrian king
Sennacherib (704–681 BC) claims to have been the
first to cast monumental bronze statues (of up to 30 tonnes) using
two-part moulds instead of the lost-wax method.
Bronze statues were regarded as the highest form of sculpture in
Ancient Greek art, though survivals are few, as bronze was a valuable
material in short supply in the
Late Antique and medieval periods.
Many of the most famous Greek bronze sculptures are known through
Roman copies in marble, which were more likely to survive.
In India, bronze sculptures from the
Kushana (Chausa hoard) and Gupta
periods (Brahma from Mirpur-Khas,
Akota Hoard, Sultanganj Buddha) and
later periods (
Hansi Hoard) have been found. Indian Hindu artisans
from the period of the Chola empire in
Tamil Nadu used bronze to
create intricate statues via the lost wax casting method with ornate
detailing depicting the deities of Hinduism. The art form survives to
this day, with many silpis, craftsmen, working in the areas of
Swamimalai and Chennai.
In antiquity other cultures also produced works of high art using
bronze. For example: in Africa, the bronze heads of the Kingdom of
Benin; in Europe, Grecian bronzes typically of figures from Greek
mythology; in east Asia, Chinese ritual bronzes of the Shang and Zhou
dynasty—more often ceremonial vessels but including some figurine
Bronze sculptures, although known for their longevity, still
undergo microbial degradation; such as from certain species of
Bronze continues into modern times as one of the materials of choice
for monumental statuary.
Before it became possible to produce glass with acceptably flat
surfaces, bronze was a standard material for mirrors. The reflecting
surface was typically made slightly convex so that the whole face
could be seen in a small mirror.
Bronze was used for this purpose in
many parts of the world, probably based on independent discoveries.
Bronze mirrors survive from the Egyptian Middle Kingdom (2040–1750
BCE). In Europe, the
Etruscans were making bronze mirrors in the sixth
century BCE, and Greek and Roman mirrors followed the same pattern.
Although other materials such as speculum metal had come into use,
bronze mirrors were still being made in Japan in the eighteenth
Chinese bells:Bianzhong of Marquis Yi of Zeng, Spring and Autumn
period (476–221 BC)
Singing bowls from the 16th to 18th centuries. Annealed bronze
continues to be made in the Himalayas
Bronze is the preferred metal for bells in the form of a high tin
bronze alloy known colloquially as bell metal, which is about 23% tin.
Nearly all professional cymbals are made from bronze, which gives a
desirable balance of durability and timbre. Several types of bronze
are used, commonly B20 bronze, which is roughly 20% tin, 80% copper,
with traces of silver, or the tougher B8 bronze which is made from 8%
tin and 92% copper. As the tin content in a bell or cymbal rises, the
Bronze is also used for the windings of steel and nylon strings of
various stringed instruments such as the double bass, piano,
harpsichord, and guitar.
Bronze strings are commonly reserved on
pianoforte for the lower pitch tones, as they possess a superior
sustain quality to that of high-tensile steel.
Bronzes of various metallurgical properties are widely used in struck
idiophones around the world, notably bells, singing bowls, gongs,
cymbals, and other idiophones from Asia. Examples include Tibetan
singing bowls, temple bells of many sizes and shapes, gongs, Javanese
gamelan, and other bronze musical instruments. The earliest bronze
archeological finds in
Indonesia date from 1–2 BCE, including flat
plates probably suspended and struck by a wooden or bone
mallet. Ancient bronze drums from
Thailand and Vietnam date
back 2,000 years.
Bronze bells from
Thailand and Cambodia date back to
Some companies are now making saxophones from phosphor bronze (3.5 to
10% tin and up to 1% phosphorus content). Bell bronze is used to
make the tone rings of many professional model banjos.[citation
needed] The tone ring is a heavy (usually 3 lbs.) folded or
arched metal ring attached to a thick wood rim, over which a skin, or
most often, a plastic membrane (or head) is stretched – it is the
bell bronze that gives the banjo a crisp powerful lower register and
clear, bell-like treble register-especially in bluegrass
Coins and medals
Bronze has also been used in coins; most “copper” coins are
actually bronze, with about 4 percent tin and 1 percent zinc.
As with coins, bronze has been used in the manufacture of various
types of medals for centuries, and are known in contemporary times for
being awarded for third place in sporting competitions and other
events. The later usage was in part attributed to the choices of gold,
silver and bronze to represent the first three
Ages of Man
Ages of Man in Greek
mythology: the Golden Age, when men lived among the gods; the Silver
age, where youth lasted a hundred years; and the
Bronze Age, the era
of heroes, and was first adopted at the 1904 Summer Olympics. At the
1896 event, silver was awarded to winners and bronze to runners-up,
while at 1900 other prizes were given, not medals.
Bronze flag found in Shahdad, Kerman, (now Iran), 3rd millennium BC
Ewer from 7th-century Iran. Cast, chased, and inlaid bronze.
Metropolitan Museum of Art, New York
Corinthian helmet from the tomb of Denda, Staatliche Antikensammlungen
museum in Munich
Woman resting on Bill Woodrow's 'Sitting on History' utilitarian
sculpture at the British Library
Croatian Apoxyomenos (detail), Mimara Museum, Zagreb
Bronze mirror with support, Metropolitan Museum of Art, New York
Tirthankara from 7th-century
The inscription, which was written in ancient bronze script,
documented the land system in western
Zhou dynasty in detail. 9th
century BC. National Palace Museum, Taipei.
Bronze and brass ornamental work
Chinese bronze inscriptions
Dezincification Resistant Brass
French Empire mantel clock
List of copper alloys
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