This section continued to raise awareness of the debris from high temperature processes by a number of training sessions, including a Slag Workshop at the Institute of Field Archaeologists' 1995 conference. Two training courses on ceramic fabrics and inclusions were also run jointly with the Central Archaeology Service. These sessions all help to ensure that standards are raised, and that our expertise and experience is passed on to field archaeologists.
A wide variety of industrial debris was assessed and analysed during the year, ranging from a small but significant late Iron Age to early Roman iron smelting assemblage from excavations at Thorpe Lea Nurseries, Surrey, to the considerable remains of Roman craft workshops on the Courage Brewery site in Southwark, where both iron and copper alloy artefacts were produced. The glassworking remains found in the 1950s excavations at Glastonbury Abbey were also reassessed and a full report produced for publication.
In several projects, artefact manufacture was investigated using non-destructive techniques. The Ripon Jewel, a fine piece of 7th-century craftsmanship, was made of several different gold alloys, all of which had compositions compatible with the suggested date of manufacture. The inlaid stones proved to be 2 different types of garnet, conceivably from the same source. A large group of knives and spearheads from the Saxon cemeteries at Mucking was studied using X-radiography, showing a high frequency of butt-welded cutting edges among the knives. The manufacture and use of decorative punches was investigated by imaging punchmarks on early Anglo-Saxon artefacts from Barrington, Cambridgeshire, in the new scanning electron microscope. Five types of punch manufacture were identified, each of which involved remarkable manufacture, since most of the punches were less than 2mm across at the tip. Apart from the simplest forms, each punch seems to have been used on only one or a pair of artefacts, suggesting a large number of punches were available.
The manufacture of some colourful glass beads found at the same site was investigated through compositional and micro-structural analysis and the results compared with those for beads from other sites. A wide variety of appearances were produced by combining different proportions of colourants and opacifiers, including the surprising incidence of ironworking slag in a red-brown bead. (see illustration)
Products of the post-medieval industry are being investigated by the Historical Iron research project. Iron producers used a variety of manufacturing processes during this period, competing in a Europe-wide market. Initially, a methodology has been developed to allow us to distinguish between the products of these different processes. Subsequent studies are investigating artefacts of this period, exploring the evidence that they can give about trade and about the qualities of the iron used.
A small but significant group of Imperial Porphyry, a unique purple coloured stone quarried in the eastern desert of Egypt was found in a large collection of coloured Roman marbles from Colchester, probably associated with an early-4th-century AD basilica-type building. The building was richly decorated with other coloured marbles, which included material from Asia Minor, Greece, the Aegean and North Africa.
This collection is currently being examined as part of a broader study of ornamental coloured marble in Roman Britain. Initial results show that the sources of supply were not constant and chronological and geographical differences can be seen, due perhaps to difficulties of supply or changes in fashion. A comparison between the Colchester marbles and those recovered from the 1st-century AD palatial villa at Fishbourne shows that the collections are quite different in their composition. At Fishbourne French coloured marbles form a key element, with very few eastern Mediterranean marbles present. In contrast, there are no French coloured marbles in the 4th-century AD Colchester group, whose coloured marbles come mostly from the eastern Mediterranean region.
