Bronze objects

There are over 3000 recorded bronze and copper Bronze Age (2500-600BC) objects recorded on the Portable Antiquities Scheme database. These objects represent the earliest evidence of metal working in England and Wales and through the study of these objects, their development, distribution and use, we can discover a wealth of information about prehistoric societies. It is vital that these finds, regardless of condition or quantity, are recorded as they are evidence of a time with no written records and few settlement sites.

Prospecting

Bronze Age bronze is typically an alloy of 90% copper and 10% tin and other metals. Some metals such as lead were deliberately added towards the end of the Bronze Age. In Britain copper ores can be found in Devon, Cornwall, north Wales, west Scotland and south-western Ireland. Tin ores are located mainly in south-west Britain. Long before the development of metalworking it is likely that people had a good knowledge of the minerals and rocks beneath their feet as these resources were exploited to create stone tools and pigments.

Extracting

In the beginning copper was probably collected from the surface and rocks were also loosened by fire setting. Eventually however it was necessary for the miners to go deeper which required more workers and therefore a higher level of organisation. Pits and mineshafts were created which makes the extraction of ores much more visible archaeologically but still difficult to date and identify often due to later mining. Archaeologists have demonstrated that Bronze Age tools such as hafted stone hammers and antler picks to be very effective mining tools. Copper ores are often located in inhospitable places so it is presumed that people often made special expeditions to mine these materials.

It is difficult to see evidence of the division of mining labour but the narrowness of the shafts and galleries in a number of mines suggests that only children and very small adults, most possibly women, would have been mining in these places. There are 17 identified Bronze Age metal mines in Britain, one of which is Copa Hill in Cwmystwyth where there is evidence of wooden guttering to assist in the drainage of the mine. With the apparent cessation of copper mining at all sites in Britain and Ireland, with the exception of the Great Orme, Wales, around 1500 BC bronze appears to have been imported from continental Europe in large quantities.

Processing

Early processing involved crushing ores with a rock and then separating by hand the copper from the host rock. Later, gravity separation might have been used where the ore is crushed and then washed so that the host rock floats away leaving the heavier particles of copper. Transporting ore and processed copper around the landscape would have been very labour intensive and needed organisation.

Smelting and Alloying

Smelting converts processed copper into metal and the equipment needed for this are a container, fuel and tools for controlling air such as blow pipes or bellows. The temperature needs to reach 1000°C and there is very little room for error even when smelting simple objects. The archaeological evidence for smelting is incredibly sparse and experiments have shown that smelting can be achieved with flat ceramic vessels which leave virtually no archaeological traces. The evidence for tin smelting is even scarcer than copper as its ore has a high purity and therefore leaves behind very little slag. Alloying is the combining of two metals and it is difficult to detect in early bronze objects if alloying is accidental or deliberate. It also becomes difficult to analyses the origins of bronze objects due to the mixing of different ores and the recycling of objects.

Working, Casting and Finishing

Bronze was worked in the Bronze Age by hammering, known as cold working and applying heat, known as annealing and casting, in open and two part closed moulds. The moulds were made out of stone, sand, clay or metal. Very few moulds have been found which indicates perhaps that the majority were made out of organic materials. The moulds would have been made by carving and the objects cast using the lost wax technique. The final stage in creating prehistoric bronze was to finish it by grinding and polishing the metal with sand, grit, water, fleeces and textiles.

Use, Circulation, Recycling and Deposition

How bronze objects were used in the Bronze Age is not always a straight forward question. Shields from the Bronze Age are far too thin to have been any use against an attacker and the same idea applies to a number of bladed weapons that are far too delicate to have been much use as a weapon. Re-sharpening and re-shaping of metal will remove evidence of what an object may have been used for and objects would have been melted down and recast. Any object could in fact have been regarded by its last prehistoric owner as an ingot or scrap destined to be melted down and reshaped into a new form with a new function. Many objects are found in burials or hoards indicating that they are not chance losses and a large number of new or nearly new objects have been discovered in watery contexts such as rivers and bogs and so are probably votive offerings.

The following guide will assist anyone who wishes to identify and study bronzes from the Bronze Age. However this is a beginner’s guide and all of the subtypes and variants of some objects have not been included. This has often been because these types are not commonly encountered in Britain.

References

  • Pearce, S. (1984) Bronze Age Metalwork in Southern Britain. Aylesbury: Shire Publications
  • Timberlake, S. (2009) Copper mining and metal production at the beginning of the British Bronze Age In: P. Clark (ed) Bronze Age Connections: Cultural Contact in Prehistoric Europe. Oxford: Oxbow Books 94-121
  • Ottaway, B., Roberts, B. (2008) The Emergence of Metalworking. In: A. Jones (ed.) Prehistoric Europe: Theory and Practice. Chichester: Wiley-Blackwell 193-225