Why Is Obsidian So Glassy?

What Crafty Clover says in this video

Intro

Hi there, curious minds! I'm Crafty Clover! Let's discover something amazing. Why is obsidian so glassy?

The Big Idea

Obsidian is natural glass made by volcanoes! It forms when lava cools so fast that crystals do not have time to grow. That makes it smooth and shiny all the way through.

Super Fast Cooling

Step one: super fast cooling. When thick lava meets cold air, water, or ice, it cools extremely quickly. The tiny particles freeze in place before they can line up into crystals.

Glassy Rock

Step two: glassy rock. With no crystals, the rock has no grains, so it is smooth and shiny like glass. It is usually black, but it can also be brown, green, or even have rainbow shimmer.

Sharp Edges

Step three: sharp edges. Obsidian breaks into pieces with razor-sharp edges, so people long ago used it for tools and arrowheads. Obsidian from a volcano in British Columbia was traded far and wide.

A Closer Look

Let's take a closer look! Lava cools extremely fast. So no crystals can grow. The rock is smooth and glassy. And when it breaks, the edges are very sharp.

Quick Facts

Quick facts! Obsidian is natural volcanic glass. Its edge can be sharper than a steel surgeon's blade. Only experts should handle sharp pieces of obsidian. Polished obsidian is used in jewelry.

Think Like a Scientist

Now, think like a scientist! Look at a clear hard candy with a magnifier, but do not eat it yet. It is sugar glass, a lot like obsidian, with no crystals. Compare it with a grain of rock salt. Which one has neat flat faces?

Outro

Obsidian is glassy because lava cooled too fast for crystals to grow. Science is amazing! Crafty Clover can be found on Amazon Books, Google Bookstore, and Apple Books. Available for purchase or download! Bye for now!