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Analysis of copper-alloy artefacts from pagan Norse graves in Scotland

By, Katherine Eremin, James Graham-Campbell, Paul Wilthew

Copper-alloy artefacts from the pagan Norse graves of Scotland were analysed using non-destructive x-ray fluorescence and scanning electron microscopy. The artefacts consist of brass, bronze, gunmetal and silver-rich copper-alloys, but were principally of brass and bronze. Different alloy traditions are apparent for Insular and Scandinavian artefacts. Brass is largely confined to Scandinavian artefacts, predominantly oval brooches. Most brass artefacts have high to moderate zinc contents, and one has an unusually high zinc content close to the maximum possible value for brass at this time. Brass artefacts with low zinc levels may have been manufactured from recycled brass with addition of copper. Use of other alloys is mainly limited to attachments, with bronze brooch pins on two brass oval brooches and copper and bronze rivets on several brass oval brooches.

Most Insular artefacts are composed of bronze, but there are some brass, gunmetal and silver-rich copper-alloys. Most of the Insular brass artefacts show Scandinavian influence and manufacture at Insular sites with Norse contact is suggested. The generally lower zinc levels suggest recycling of brass artefacts with high zinc levels from Scandinavia with the addition of copper only. This implies careful recycling of metals on Insular sites. The gunmetal artefacts suggest some random recycling of mixtures of tin- and zinc- bearing copper alloys. A few artefacts consist of silver-rich bronze, including Insular, Scandinavian and Exotic examples. The silver content is too low to appear as white metal and two are tinned and one mercury gilded. These silver-rich copper-alloys suggest limited random recycling using mixtures of copper and silver alloys.

The main decorative features on the artefacts are mercury gilding and tinning, with silver wires and inlay on some Scandinavian artefacts. Brass was relatively rare in Britain from the late Roman to early Medieval period. Its use in areas of Norse contact suggests introduction from the Continent and Scandinavia. The careful recycling of brass indicates that this was a highly valued alloy.

Keywords: Pagan Norse graves, Scotland, brass, bronze, gunmetal, silver-rich copper-alloys, recycling, mercury gilding, tinning, Scandinavia, copper-alloy