As water flows through the geode, additional mineral layers are deposited in its hollow interior. Over thousands of years, these layers of minerals build crystals that eventually fill the cavity. How long this takes depends on the size of the geode — the largest crystals can take a million years to grow.

Will geodes continue to grow?

No, you are right. They won't continue to grow. They need to be kept in a supersaturated solution to grow.

Do geode crystals grow?

Geodes are rocks with air pockets inside that have crystals growing inside them. They can look very ordinary on the outside, but beautiful on the inside!