- The Technology of Metalwork -
(or three with lead), iron alloys either derived directly from a single ore with
iron-phosphorus alloys or from reactions between iron and carbon in the form of
charcoal when iron-carbon alloys (steel) were being made. Once the technology was
widely disseminated, most areas had a local supply of metal, although there is also
sufficient evidence of long-distance trade in iron for special purposes. Indeed, it is
almost certainly the way in which the technology was controlled and transferred that
dictated the pace at which iron was adopted, a process for which we have minimal
archaeological evidence. For many purposes the actual properties of iron alloys
offered little advantage over their copper-based competitors but their superior
toughness or resistance to brittle fracture would have been attractive in daily use; cast
bronze is brittle and fracture was a common mode of failure in bronze tools. Finally,
although the blacksmith's skills of forging, welding and carburizing are as complex
as those of the bronze founder and bronzesmith, being able to dispense with the
paraphernalia of casting - crucibles and moulds - was probably regarded as another
improvement.
RESOURCES
Many years of effort, not always successful, have been invested in locating the
copper, tin and lead resources exploited in the Bronze Age and linking them with
objects derived from those ores. Recently, for example, considerable excitement has
been generated by the identification and dating of bronze age copper mines in Britain
and Ireland. Similarly, the exploration and excavation of Roman mines has been a
topic of research since work of Oliver Davies in the 1930S (Davies 1935). Possibly
because interest has naturally been focused on the new metal, iron, there has been
very little investigation of the non-ferrous metal resources used by Celtic smiths and,
outside Britain, only a limited amount of scientific analysis of iron age copper alloy
metallurgy. As yet no iron age copper mine has been found in Britain. However,
there is good evidence for the exploitation of British copper and, probably, tin
resources during the La Tene period and some of the earliest raw copper yet found
on metalworking sites (Musson et al. 1993).
Although it makes good sense to assume that British copper ores were being
mined and smelted during the Late Bronze Age, there is no direct evidence. The
copper ingots, common in the ninth-eighth centuries BC in southern and eastern
England, appear to have been exported from the Continent, although a few may
come from the south-west, where there is also a limited distribution. A dependence
on scrap bronze from the Continent, and also from Ireland, is also evident. For the
seventh-sixth centuries there are even fewer clues and it is quite possible that by
the end of the sixth century BC copper and tin extraction had virtually ceased in
Britain. Lead mining probably stopped even earlier as the alloys of this period are
mainly lead-free.
Even in the earliest La Tene period there were the beginnings of a revival in
metallurgical activity and new, previously unused copper deposits were opened up.
The best example of this is in the area of the Llanymynech hill-fort and the Tanat
valley, just on the Welsh side of the Powys/Shropshire border. Two hearths excavated