In 1931 American chemical engineer Samuel Kistler invented the lightest known solid--an aerogel--by drying a form of silicon dioxide (a raw material for glass) under intense pressure and high temperature.

FORBES: Magazine Article

With glass as well as plastic in mind you might want to look into another raw material, soda ash.

FORBES: Magazine Article

The raw material is converted into soda ash, used in detergents and pharmaceuticals and in the manufacturing of glass.

BBC: Working Lives Kenya: Chemist