What is glass made of?
What Is Glass Composed of
Glass is made of a mixture of minerals and each manufacturer has their own formula. Also the composition varies in accord with different intended uses. Basically, there are three main companents:
Formers (silicon oxide=sand). They are the "backbone" of the glass mix
Fluxes (i.e.sodium carbonate). These are necessary to lower the melting point of glass
Stabilizers. They lower the risk of corrosion of the glass (to some degree)
There is an excellent article on the Dow Corning website explaining the composition of glass. Read it here