Summarize this article in one sentence.
You don't use harsh chemicals to clean a geode. Stick to a simple mixture of water and laundry detergent. Mix a splash of laundry detergent with warm water and gently swab the geode with a toothbrush. As the geode will need to soak to get completely clean, you will not be able to get off all the dirt and debris in the first round of cleaning. Simply strive to do your best. Mix a tub of water with a quarter cup of any household bleach. You can buy bleach at a department or hardware store. Submerge the geode in the bleach and let it soak for 24 hours. Make sure to wear gloves when handling bleach. After the geode has soaked, you can wash off the remaining dirt and debris. You can buy denture cleaner at most department stores. Use denture cleaner and a soft-bristle toothbrush to scrub off any remaining dirt stuck to the geode. Dirt that did not come off during the first round of cleaning will come off more easily after the geode has been soaked. Geodes have a lot of cracks and crevices. When cleaning the geode, make sure to get into these cracks to remove any dirt. Strive to be very thorough and inspect any crevices closely for lingering debris.

Summary:
Wash the geode with laundry detergent and water. Soak the geode in bleach for a day. Clean the geode with a toothbrush and denture cleaner. Get into any crevices.