Tourmaline is a colorful gemstone that comes in a variety of hues, including pink, green, blue, and black. It is a silicate mineral composed of boron, aluminum, and other elements. Tourmaline is known for its unique ability to exhibit multiple colors in a single crystal, a phenomenon called "bi-color" or "tri-color." This makes it a popular choice for jewelry and decorative items. In addition to its aesthetic appeal, tourmaline is believed to have various metaphysical properties. Some people think it can promote healing and balance energy. The gemstone is also used in electronics, as certain types of tourmaline can generate electricity when subjected to pressure, a property known as piezoelectricity.