Willemite, Calcite - image 1
Photo by Earl R. Verbeek

Willemite, Calcite

FM
Franklin Mineral Museum
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Willemite veins transecting willemite-calcite zinc ore from the 430 level, Sterling mine, Ogdensburg, New Jersey. Hydrothermal fluids have destroyed the fluorescence of the ore within 2 to 3 cm of the veins. The specimen is 39 cm long. Earl R. Verbeek photo.

Product details

SpeciesWillemite, Calcite
SizeMuseum
Dimensions3900.0 cm
Added on02/13/2026
LocalityUSA, New Jersey, Sterling Hill Mine
Publications
  • Mineralogical Record Mineral Collections In American Northeast page 143

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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 Sterling Hill Mine, New Jersey, USA
Sterling Hill willemite is one of the classic collector materials of American mineralogy: a zinc silicate, Zn2SiO4, that can look modest in daylight and then turn electric green under ultraviolet light. In the best pieces, tan to reddish-brown willemite crystals sit in white calcite with black franklinite and, less commonly, red zincite—an ore assemblage so distinctive that even small fragments announce the Franklin-Ogdensburg district at a glance. The daylight palette is earthy and old-mine: mahogany, brick red, honey brown, buff, white, and black. Under shortwave UV, however, willemite becomes the bright green signal in the rock, while calcite may burn red to orange-red and franklinite stays dark.