TESSERAE- a Latin term for square object; individual units of cubes of stone, glass, or terracotta.
SMALTO/I- handmade glass made up of alkaline substances such as lead; known as Venetian glass
Originally mosaics were constructed from cut or carved stone tesserae. Pebbles, marble, and travertine tile were the most poplular mediums by the Romans until glass tesserae were developed into an industry. The most common type of glass mosaic in the region is referred to as smalti.
Smalti is developed through a process of annealing vitreous paste consisting of a mixture of lead, sand, and various metal oxides. A wider range of color became available to mosaic arists, through natural pigments added to the mixture. The use of gold leaf pressed in the glass began a defining trait in Byzantine mosaic as it was the lavish element that gave religios subjects that atmosphere of spirituality. The prescence of gold leaf mosaics is apparent throughout San Marco.
Unlike stone which provides a limited palette of earth tones, glass smalti offers more color options to choose from specifically for constructing images to inspire reverence. The brilliance of color and sheen creates an atmosphere of opulence and divinity through the effects of light refraction off the surface, changing the look of an image at different times a day depending on the light source.
Evolution of technique in the application process of mosaics can prove insightful in determining the changes in style as Venice sought to distinguish itself as a separate entity from mainland Italy and the Byzantine Empire. Creating their own glass production is an example of taking steps to become independent.