Tourmaline has piezoelectric and pyroelectric properties, and other unique physical and chemical properties, therefore, has far-infrared band of electromagnetic radiation, negative oxygen ions and antibacterial, deodorant and other functions. Changes in temperature and pressure can cause a potential difference of tourmaline crystals so that ionize the surrounding air, was hit near the electronic attachment to water and oxygen molecules and make it into the air ions, the negative oxygen ions. Negative oxygen ions move in the air, the negative charge transfer to the bacteria, dust, smoke particles and water droplets. Charge and the combination of these particles gather into a ball and sink, so as to achieve the purpose of purifying the air. Slate is mainly used for electrical ground, walls, bathrooms and other decorative areas.