A diamond grows 150 km under your feet. Dig down, then ride a volcano back up with it.
🌍 Play this lesson on the globe
At Kimberley, in South Africa, diamonds were first found in a bluish rock, so the rock was named kimberlite. But those diamonds grew far below your feet. How did they get up here?
A diamond is pure carbon, and so is the graphite in your pencil! In graphite, the carbon lies in flat sheets that slide apart, so it’s very soft. Diamond is the same carbon, packed another way.
Where could a diamond grow? Drag the slider to dig straight down, and watch the squeeze and the heat. The blue band shows where most diamonds grow (the picture is simplified).
Diamond mines aren’t just anywhere: as far as geologists know, kimberlite rich in diamonds is found only on the oldest parts of the continents. Geologists call each old core a craton. Tap a blue dot to visit a mine, and spin the globe to find Canada.
Make a guess first. Then tap the button to erupt a kimberlite volcano under Botswana.
Guess, then try: Did the volcano make the diamonds, or carry them up? (Made them / Carried them)
Lots of people think diamonds are squashed coal, but it’s not true! Coal is made from old plants, buried in layers in the crust. Diamonds grow about 150 km down in the mantle, far below any coal.
Diamonds are mined in Africa, Canada, Australia and Russia. One country digs up more than any other. Hint: it’s the biggest country in the world, and its giant Mir mine is in cold Siberia.
🌍 Play this lesson on the globe
The globe pictures are simplified to show the idea. Earth images: NASA Blue Marble (public domain).