Mochi Isle
Crystal growth · Crystal MineScience for kidsHow do crystals grow?
In short: When water holds more dissolved material than it can keep, for example as it evaporates or cools, the extra material lines up in neat, repeating patterns and grows into crystals. Sparkly stones mostly reflect light rather than glow.
How it works
In a crystal, atoms or molecules stack in the same pattern over and over, like neatly clicked-together building bricks. That is why a grain of salt is a tiny cube and snowflakes usually have six sides. Different patterns give different crystal shapes.
Crystals can grow from a solution, which is a liquid with something dissolved in it. As salty water slowly evaporates, the leftover salt lines up into crystals. Slow growth gives atoms time to line up neatly, so crystals tend to be bigger. Crystals also grow in slowly cooling magma.
Many crystals have flat, mirror-like faces that bounce light back, and some split light into rainbow colours, so they sparkle. But that light is only reflected. It is completely different from a firefly making its own light: switch off the lamp and the sparkle disappears.
Where to see it in New Zealand
At Lake Grassmere / Kapara Te Hau in Marlborough, seawater is let into shallow ponds where sun and wind slowly evaporate the water, leaving salt crystals behind. On frosty winter mornings, the white coating on the grass is made of tiny ice crystals too.
Try it together
With an adult's help, stir salt into a small cup of warm water until no more dissolves. Pour a little onto a dark plate and leave it on a sunny windowsill. After a few days, use a magnifying glass to look for tiny cube-shaped crystals.
Kids also ask
Do sparkly stones give off light?
Usually not. They reflect and bend the light around them, so they only sparkle when light shines on them. A few minerals glow under a special ultraviolet lamp, but they are giving back energy from light they have absorbed.
Why are some crystals big and others tiny?
It mostly depends on speed. Slow growth gives atoms time to line up, so crystals get larger, while fast growth makes lots of small grains. That is why slowly cooled magma often has bigger mineral crystals.
In the game, “Crystal growth” is a nature card on Crystal Mine.
Your child finds this card by reaching the right place or meeting the right weather on the island, and lights it up by answering the question on the back. Tap the button below and the game shows your child which island it is on and how to find it. Mochi Isle is a browser learning game for ages 5 to 18; the main island and the daily lesson are free.
Find “Crystal growth” on the island ↗ All cards from Crystal Mine