What crystals cannot be cleansed in salt?
Crystals like Selenite and Halite should not be cleansed in salt as they are water-soluble. Metallic stones such as Pyrite and Hematite can rust. Porous varieties including Opal, Turquoise, and Malachite, plus softer crystals like Calcite and Fluorite, may be etched, scratched, or suffer damage to their polish and integrity from salt exposure.