Mother-of-pearl, jet coral and amber were selected by craftsmen for their beauty, durability and rarity. These materials often occurred in a particular geographical region. Coral for example was prevalent in Sicily and amber along the Baltic coast. Many of the religious items were portable, as were the small portraits. They were often made locally and then taken elsewhere. Pilgrims from all over Europe bought the jet images made in Santiago de Compostela.
This Virgin and Child was almost certainly once mounted on a socle. It is partly worked on the back, suggesting it was intended to be seen in the round.
In structure jet is a particularly dense type of coal, and can be carved and polished. Medicinal and indeed magical qualities were thought to be inherent in the substance from earliest times. Jet is found in different parts of Europe (as well as North America), but the two richest regions are the Asturias in northern Spain, and Whitby, Yorkshire, in North East England.