Under visible light, this ore-bearing slab seems like an ordinary stone. But when exposed to ultraviolet light, this slab of rock showcases the spectacular fluorescent minerals within. Zinc-bearing minerals cause it to glow in green, while zinc-free calcite is what makes it glow in red. This extraordinary specimen, known as the Sterling Hill Slab, comes from the Sterling Hill Mine in Ogdensburg, New Jersey.
About 90 fluorescent mineral species are found at Sterling Hill and the neighboring Franklin deposit, some of which have been found nowhere else on Earth. See this specimen up close in the Museum’s Mignone Halls of Gems and Minerals!
Photo: D. Finnin / © AMNH
Hey, check it out! I've thin sectioned this rock (well, rock from this locality)! It's absolutely one of my favorite localities just for the sheer weird factor — over 400 minerals listed on mindat (~10% of the minerals known to science!!!) of which 91 fluoresce, type locality of over 10 minerals (including zincite, franklinite, and tephroite), and one of the only places in the world that it was viable to mine for zinc without mining sphalerite! I highly recommend reading up on it if you're curious.
Cal = Calcite (CaCO3); Fo = Forsterite (Mg2SiO4); *Frk = Franklinite (ZnFe2O4); Wlm = Willemite (Zn2SiO4); *Znc = Zincite (ZnO)
*Type Locality in Franklin or Sterling Hill
PPL / XPL
And the billet (with glass slide on top) for good measure. White is calcite, Red/orange/yellow is zincite, black is franklinite, and the little bits of brown are willemite.
