Calcite is a 3 on the Mohs scale of mineral hardness, which means that it is one of the softest minerals that will stand up to crafting, cleaning and refining. Calcite must be cleaned with this in mind; if it is not cared for while cleaning, the stone will become scratched or crumble.
Brush the dry calcite with the toothbrush. Try to remove loose bits of dirt and dry clay from the surface with the toothbrush and your fingers.
Place the calcite in a bucket in a single layer at the bottom. Pour water into the bucket and allow the stones to soak.
Empty the bucket. If the stones are still dirty, you can try pressurized water such as with a dentist's wand or try to scrub moistened bits of grime from the stone with the toothbrush. If the stone is still dirty, move on to the next step.
Place the stones back in the bucket. Fill it with water. Add 1 tbsp. baking soda for every gallon of water the stones are soaking in. The baking soda will lift the dirt and stains from the stones.
Remove the stones from the baking soda water. Rinse them with fresh water and allow them to dry before putting them on display or tumbling them.
Some stains will not come out of calcite. If a stone looks as if it has been rusted, try applying iron remover instead of baking soda.