Willemite and Franklinite are two different minerals that are frequently found together at this deposit (Franklin, New Jersey, USA). Franklinite is an oxide of zinc, iron, and manganese. Willemite, on the other hand, is an oxide of zinc and silicon. This mineral is highly fluorescent, producing a striking green color. This combination of minerals is also accompanied by calcite, which provides an intense pink tint under ultraviolet light.