Hand wash only.
For lava rock:
If your bowl is going to come in contact with any food you will need to season it before using. Place coarse rock salt into the bowl. Grind the salt into a fine powder using a pestle or wooden spoon. Now your item is ready to use.
Wash with warm water immediately after use to prevent staining.
Never use soap! A stiff wire brush with little water and a little scrubbing and then allow your lava rock bowl to air dry.