Most geodes contain clear quartz crystals, while others have purple amethyst crystals. Still others can have agate, chalcedony, or jasper banding or crystals such as calcite, dolomite, celestite, etc. There is no easy way of telling what the inside of a geode holds until it is cut open or broken apart.

How do you tell if a geode has crystals inside?

Geodes will sometimes have loose material inside, which can be heard when shaking the rock. You can also tap lightly with a stone or hammer to see if it sounds hollow. Geodes are usually lighter than their size would indicate since the interior doesn't contain any material.

Do geodes have crystals on the outside?

Look at the Shape

Once you're on site, look for round oval rocks that have lumpy surfaces. Geodes will look like plain old rocks on the outside, but as you know will have beautiful crystals on the inside, making them wonderful items to display in a display case.