Willemite is a mineral composed of zinc silicate, often found in a greenish or yellowish color. It typically forms in hydrothermal veins and is commonly associated with other minerals like sphalerite and calcite. Willemite is known for its fluorescence, emitting a bright green light under ultraviolet light, which makes it popular among mineral collectors. This mineral is primarily mined for its zinc content, which is essential for various industrial applications, including galvanizing steel and producing alloys. Willemite can also be used as a gemstone, although it is less common in jewelry compared to other minerals.