Each Quartz Geode will arrive closed and maybe a little sandy, but when you gently prise the two halves apart you will see within the most beautiful Quartz formations. Large is about the size of a yellow melon. The two pieces fit perfectly to form the natural geode which when held in your hand looks like a piece of dusty old rock. It's not until you open it that it's true glory is revealed.
They are themselves of sedimentary origin formed by chemical precipitation. Geodes are essentially hollow, vaguely spheroid to oblate masses of mineral matter that form via either of two processes:
- by the filling of vesicles (gas bubbles) in volcanic to sub-volcanic rocks by minerals deposited from hydrothermal fluids or
- by the dissolution of igneous nodules or concretions(that were deposited syngenetically within the rock formations in which they are found) and partial filling by the same or other minerals precipitated from diagenetic water, groundwater or hydrothermal fluids.