Willemite

Learn more

Mineral guide

Learn about Willemite

fluorescent zinc silicate with UV glow; daylight colors range from colorless to pistachio, iconic from Franklin–Sterling Hill and Tsumeb.

Regional guide

Willemite from Tsumeb, Namibia

Tsumeb willemite is the zinc silicate for collectors who usually think of willemite as a fluorescent-mineral classic from Franklin, New Jersey, and then discover that Tsumeb rewrote the aesthetic rules. Here, Zn2SiO4 appears not as massive ore but as glassy to sparkling crystal groups, botryoidal crusts, radiating sprays, delicate acicular “lawns,” and rare individual hexagonal prisms. The colors are equally un-Franklin-like: white, gray, yellow, green, blue-green, turquoise-blue, pale blue, reddish brown, and the much-loved champagne to honey tones. The best pieces have a crisp, jewel-like presence in daylight, often on white calcite or dolomite, with the color contrast that Tsumeb collectors prize.