Back in October 2014 The Guardian (www.theguardian.com/culture/2014/oct/17/staffordshire-hoard-anglo-saxon-… … the discovery of a hoard of metal in a Staffordshire field led to some forensic science behind the scenes – with a surprising result. The Anglo Saxons of Mercia, it is alleged, reinvented a Roman process that gave lower grade metal with a high silver content the appearance of pure gleaming gold. As similar technology is recorded from Roman accounts this really amounts to a survival of knowledge rather than reinvention of an elaborate technique. The process involved taking a gold and silver alloy and heating it in an acid solution (made from iron rich minerals such as brick dust) so that the surface silver leached out and could be burnished off. The surface would then appear to be pure gold – and more valuable.
This would require continuity of knowledge which would imply continuity of humans (tending to detract from the idea of a mass Anglo Saxon invasion). However, similar metalwork was later found amongst the Sutton Hoo ship burial treasure – which suggests the Angles were akin to the Vikings of somewhat later and the treasure was in fact loot. The Angles hailed from Denmark. Obviously, the time scale is important, and the cultural milieu or theme of the gold/silver items (was it A/S or was it Roman period?) In addition, if the technique was known in Roman period Britannia it was also known in Gaul and Belgica. Newcomers could have brought the technique with them from the continent (having learnt it from the Romans). Whereas all these ideas are possible we have to bear in mind that working with precious metals is and always was a skilled job with a restricted access. Such metalworkers would have been prized – by newcomers as much as by the Romano British. More evidence is required – a workshop for example.