Willemite and Rosasite on Calcite - image 1

Willemite and Rosasite on Calcite

Unknown Owner
Willemite is a rare and fascinating zinc-bearing mineral species: one which in some instances (eg Franklin) is vividly fluorescent under UV light, but pretty ugly and dull in normal light; whilst at Tsumeb mine it is more colourful and glassy, but less obviously fluorescent. This very well balanced larger miniature-sized specimen from Tsumeb mine features iconic duck-egg blue Willemite as globular aggregates ranging from 2 to 5 mm in diameter sat upon a crust of bright white Calcite and with minor Rosasite in association. The Willemite also occurs as small prismatic crystals with 'domed' terminations giving the impression of rounded spheres end-on. It is a really lovely display of this much sought-after colour and form of Willemite. Ex Weyand Collection.

Product details

Species
Willemite, Rosasite, CalciteAbout Willemite →
SizeSmall Cabinet
Dimensions6.0 x 5.2 x 2.7 cm
Added on01/14/2026
Locality
Namibia, Oshikoto Region, TsumebRegional guide →

Known provenance

DateCollectorAcquisition price
—Unknown Owner$950.00
—Crystal ClassicsNot disclosed

Learn more

Willemite
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.
Willemite
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.