Tesserae - tessara

Small pieces, usually cubes, used to create a mosaic. A single piece is a Tessara. The most common materials are colored glass, ceramic, stones or metal. Traditional Tesserae from Venice, used from the Middle Ages, are opaque glass in myriads of colors, and are usually set into the mosaic with the fractured side exposed to create a sparkle from reflected light. Mosaics from ancient Greece and Rome and other civilizations were composed of larger Tesserae, many which were naturally colored pebbles. Byzantine mosaics were made with gold Tesserae, which was gold leaf placed between two layers of clear glass. Sources: Kimberley Reynolds and Richard Seddon, "Illustrated Dictionary of Art Terms"; Ralph Mayer, "A Dictionary of Art Terms and Techniques" (LPD)