The Discovery: Mosaic Materials
The mosaic is made from small cubes of natural stone and terracotta possibly cut from tile or brick. Each of these small cubes is called a tessera (several tesserae) from the latin word for dice.
Section diagram showing how the layers were built up to support pavements and possibly this one.
The tesserae were laid on a surface layer of fine mortar that was applied freshly for each days work. Below that was a layer containing terracotta, nucleus. This rested on a coarser layer of well compacted mortar, rudus, which in turn lay on a layer
of compacted rubble, statumen.
Lime mortar becomes harder more quickly with the addition of terracotta and was called opus signinum, from the Italian city of
Sigma were it is thought to have been developed.
Colours used in the mosaic and their origins
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