Beads of time

Figure 1 Two Iron Age Scottish beads. (a) This bead has a body of translucent amber glass and a tightly coiled spiral of opaque yellow glass. The amber colour stems from the formation of ferri-sulfide compounds in the melt, both elements deriving from the simple impurities in the raw materials (iron impurities in the sand and sulfur impurities of the natron). The yellow lead antimonate glass received a long and complex treatment for the achievement of the colour.

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A collection of beautiful glass beads has been discovered in Scotland. Their origins are a mystery, but analytical chemistry, including techniques such as mass spectrometry, can shed light on their composition, which in turn provides clues as to how and where they were made. The glass consists of oxides of various elements, combined with pigments and crystals to produce colours and effects. It seems that the evidence points to an ancient form of glass recycling between the Romans and Iron Age Caledonians.