I assume he means glass for lensmaking.
A few compact cameras have been made using lenses with ceramic elements, rather than glass, which apparently can be managed into different shapes, be thinner, and is more scratch resistant. As far as I know, hoever, it's still more expensive, or at least nobody has a setup for make mass quantities of lens elements from it and can't be bothered to invest.
Someday in the future, I'm interested in the possibility of lens elements made of artificial diamond, which is steadily becoming cheaper to make. Not cheap yet, but some predict it will replace silicon for circuitry, and when we can make enough to put cheap diamond circuits in everyone's consumer electronics, we can make enough to put into lenses at not too much greater cost. Given the orderly atomic structure of diamond, as opposed to more disorderly structure of glass, I'm sure it can be optically excellent.
