Today, Squeaks and I are exploring some super strong rocks! We have a fun way to test which rock is harder by scratching one rock against another. If a rock leaves pieces behind when scratched, it’s not as strong. The rock that doesn’t crumble is stronger.
One of the strongest materials you might not expect is a diamond. But wait, are diamonds really rocks? Well, not exactly. Diamonds are actually crystals. This means they are solid and, if you look really closely with a special microscope, you’ll see they are made of tiny pieces arranged in a repeating pattern.
Rocks are made of lots of different crystals mixed together. If you mix a diamond with other crystals, it becomes a rock. But diamonds are stronger than any other rocks and crystals! This is because of what they are made of and how they form.
Diamonds are made from carbon, a special material found in many things on Earth. Carbon is in rocks, pencils, paper, and even in you and me! Depending on how carbon is arranged with other materials, it can look very different. It’s like using building blocks to make different things like a tree, house, or mountain.
For carbon to become a diamond, it needs to be heated up really high and squished together super hard. Most diamonds formed a long time ago, between 1 and 3 billion years ago, deep underground, about 150 kilometers down. This is much deeper than any hole humans have ever dug.
Deep underground, the Earth is incredibly hot, like the inside of a volcano. The carbon there was heated and squished by the pressure from all the stuff on top. This heat and pressure made the tiny bits of carbon stick together in a regular pattern, forming diamonds.
Even after forming, diamonds were still deep underground. Then, something amazing happened. The molten-hot insides of the Earth erupted towards the surface, like a super deep volcano. These eruptions carried diamonds and other materials up to the Earth’s crust, near the surface.
When they reached the surface, the diamonds and surrounding rocks cooled down. Many diamonds stopped just below the surface and kept their special shapes. Over billions of years, people started finding diamonds in the ground. Today, people dig up diamonds to sell and use in jewelry or special tools because they are one of the strongest materials in the world.
Thanks to one of our viewers, Rishabh, for asking about this amazing topic! What strong rocks can you find where you live? Can you think of other ways to test the strength of rocks and crystals like diamonds? If you have ideas, ask a grown-up to help you visit our website at patreon.com/scishowkids to share them. See you next time at the Fort!
