Book 27, Question 7
Is glass a crystal?
No.
Ordinary glass is made by melting sand with a few other ingredients and then cooling it so fast that the atoms freeze in place before they can line up. The atoms are jumbled like a crowd instead of lined up like a marching band. That kind of solid is called amorphous. Glass breaks into curved, shell-like pieces, while real crystals tend to break along flat lines. Because glass has no crystal faces, it can be shaped into windows and lenses.