Is glass really made of sand?

Yup – it’s crystal clear to us! You have to use sand made from quartz though. (Quartz is one of the most common minerals found in sand.) Mix the sand with lime and soda (no, not the kind you eat and drink; lime and soda are chemical compounds), and heat the mixture until it melts. The super-hot liquid looks something like thick, syrupy toffee, which is poured or shaped. As it cools, the liquid hardens into glass.