Menthol Crystals are clear, colorless, crystals that are a natural by-product of steam-distilled peppermint essential oil (Mentha arvensis). Menthol is the chief constituent of mint oil and is responsible for its distinctive odor and the cooling sensation it produces when applied to the skin. Menthol crystals are cooling, refreshing, and have an extremely strong, minty aroma. Since Menthol crystals are so concentrated, only a tiny amount is needed! Please use caution when first using. Cautions: - Not to be used in or near the eyes. - For external use ONLY - Keep away from children and avoid during pregnancy. **NOTE: Menthol crystals must pass through the Phoenix, AZ postal system, where temperatures easily exceed 100 degrees If in summer months. Your crystals may show up melted. You can place them in your fridge and lightly hit them with a rubber mallet. Please do not order if this is a problem for you.