Amethyst is a brilliant purple quartz crystal, valued for its vivid colour and beauty. Amethyst geodes, which are usually broken into two halves to display the purple crystals within, typically have many small crevices where dirt may get trapped. If the amethyst geode has been left on a dusty shelf, or is open out in the elements, the dirt and debris will often hide the sparkle of these crystals. Cleaning amethyst geodes requires getting the dirt out of the crevices, as well as cleaning the surfaces of the individual crystals within the geode.
Place a towel or rubber mat down in your sink to protect the geode (and your sink). Place a teaspoon of dish detergent directly into the geode.
Fill the sink with water until the geode is completely covered. Let it soak for 15 minutes to loosen dirt.
Gently scrub the geode, inside and out, with a small bottle brush or toothbrush (soft-bristled). The brush is necessary to remove dirt from crevices, but use a gentle touch so you don't dislodge small amethyst crystals.
Rinse the geode with distilled water--using distilled water prevents mineral deposit residue on the amethyst. Inspect the amethyst crystals for remaining dirt. Brush the geode again with detergent if any grime remains.
Place the geode on a towel, in a well-ventilated area to dry.
Many amethyst geodes will come clean through just the detergent and water cleaning. If additional cleaning is necessary, mamasminerals.com suggests soaking the geode in bleach (1/4 cup). Place the geode in a plastic bucket and carefully pour the bleach into the bucket (along with sufficient water to cover the geode completely). Let the amethyst geode soak in this solution for two days. Remove it, rinse it, and brush the geode with a soft toothbrush and denture cleaner, also recommended by mamasminerals.com.