How is glass made? — Ishaq, Jeddah, Saudi Arabia
Marshall Brain Answers:
The simplest glass is made by melting sand. For example, if a bolt of lightning hits a sand dune, its heat forms a Fulgurite in the sand, which is the simplest glass.
But at a glass factory, they usually add soda lime, cullet and a few other ingredients to the sand to make it easier to melt the glass and to create a more consistent product, as seen here:
For more info see: What makes glass transparent?