Marble and venetian glass smalti.
Arianna Gallo is based in Ravenna, Italy. Yes, that Ravenna. And she has a most impressive mosaic CV.
So its not surprising that she is responsible for this very witty little table. And it had me looking twice because the 50 and 100 denomination paper bills are the same colour as the Australian ones with our $10 being blue rather than our $20. Check out her photostream as there are many interesting mosaics there including work on some very very known modern Ravenna mosaics.
And yes, she does give lessons :).