According to the Wikipedia entry, Mosaic is the art of creating images with small pieces of colored glass, ceramic, marble, pebbles, mirrors, shells and china. It may be a technique of decorative art, an aspect of interior decoration or of cultural and spiritual significance such as in a cathedral.
The term for each piece of material is Tessera (plural: tesserae). The term for the spaces in between which are filled with grout is the Interstices. Andamento is the word used to describe the movement and flow of Tesserae. The 'opus', Latin for ‘work’, is the way in which the pieces are cut and placed.
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