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, making it popular among mineral collectors. This mineral is primarily mined for its zinc content, which is essential in various industrial applications, including the production of galvanized steel and brass. Willemite can also be found in some locations in the United States, particularly in New Jersey, where it was first discovered.