Corundum

Corundum is a very special type of rock. It is made up of a mineral called aluminum oxide. It is also known as ruby or sapphire, which are very precious gems that can be found in corundum.

Corundum is formed deep inside the Earth when hot magma, which is like hot melted rock, cools down slowly over a long, long time. As it cools, the aluminum oxide molecules come together and form crystals. These crystals make corundum rock.

Corundum rocks are very hard. In fact, they are one of the hardest minerals on Earth! This means that it is difficult to scratch or break them. That's why they are used to make things like grinding tools, sandpaper, and even bulletproof windows!

The most exciting thing about corundum is when it becomes a gemstone. Some corundum rocks have impurities that give them different colors. If it has chromium impurities, it becomes a beautiful red gemstone called ruby. If it has titanium or iron impurities, it becomes a gorgeous blue gemstone called sapphire.

After the corundum is found, it is cut and polished to make it shiny and pretty. Jewelers then use these gemstones to make jewelry like rings, necklaces, and bracelets.

So, corundum is a special rock that can turn into beautiful gems like rubies and sapphires. It's super hard and used for lots of things, and when it becomes a gem, it can be made into beautiful jewelry!