Dear Tali,

We can make glass in factories and we can find it in nature. Some volcanoes make glass. When they spew out lava, it often cools into obsidian, a black glass. Glass can also form on sandy beaches. Small tubes with smooth glass on the inside may appear after super-hot lightning strikes the sand.

In fact, sand is one of the most important ingredients we use to make glass. We may also use things like seashells, salt, and other chemicals. That’s what I found out when I visited my friend John McCloy, an engineer at Washington State University. McCloy and graduate student Continue reading Glass: How is it made?