The surprise is part of the product. The crystal formation inside is naturally variable, so the size, pattern and appearance revealed when it is opened cannot be chosen or guaranteed from the outside. It is worth making that clear, especially for online sales.

It can be opened, but breaking rock with a hammer can send sharp fragments in different directions. Safety goggles should be worn, the geode should be opened on a suitable stable surface away from other people, and children should only take part with close adult supervision.

Calcite is relatively soft, rating 3 on the Mohs hardness scale, so polished surfaces and crystal edges can be scratched or chipped through rough handling. In store, avoid piling pieces together and use trays, stands or lined shelves where they cannot continually knock against one another.

For normal dust, a soft dry brush or cloth is usually enough. Avoid vinegar, acidic cleaners and harsh household chemicals: calcite reacts even with weak acids, which can dull or damage the surface.

Yes. Products described as opened geodes have already been opened to expose the internal crystal formation, so there is no preparation needed before putting them on display. Give them a stable position where customers can see the crystal interior without the edges being repeatedly knocked.

They can be interesting geological specimens for supervised learning, but they should not automatically be treated as toys. Crystal edges and broken rock fragments can be sharp, and opening a closed geode requires sensible adult supervision and eye protection.