Willemite Fluorescent Calcite, from Franklin, New Jersey, U.S.A. (REF:53)

Willemite is a zinc silicate mineral and minor ore of zinc and can form with red zincite and franklinite (black isometric octahedral crystals and masses). Willemite fluoresces vividly from its white appearance to green and orange when placed under a short wave UV light. The red zincite and franklinite are not fluorescent.

It occurs in many places, but is best known from Arizona and the zinc, iron, manganese deposits at Franklin and Sterling Hill Mines in New Jersey.

The name Willemite was given in honour of William I (Willem) (1772-1843), King (1813-1840) of the Netherlands by Serve-Dieu Abailard "Armand" Lévy in 1830.