Agate geode
Geodes can form in any cavity that is buried. These can be gas bubbles in igneous rocks, pockets under tree roots, vesicles in lava after a volcanic eruption, or even animal burrows. Over time, the external wall of the cavity hardens, and dissolved silicates and/or carbonates are deposited on the inside surface. Over time, this slow feed of mineral constituents from groundwater or hydrothermal solutions allows crystals to form inside the hollow chamber. Then, over millions of years, the geode makes its way back to the surface through normal geologic processes.
Agate geode
Geodes can form in any cavity that is buried. These can be gas bubbles in igneous rocks, pockets under tree roots, vesicles in lava after a volcanic eruption, or even animal burrows. Over time, the external wall of the cavity hardens, and dissolved silicates and/or carbonates are deposited on the inside surface. Over time, this slow feed of mineral constituents from groundwater or hydrothermal solutions allows crystals to form inside the hollow chamber. Then, over millions of years, the geode makes its way back to the surface through normal geologic processes.