Fluorescent Minerals
Fluorescent minerals absorb ultraviolet light and re-emit it as visible colour. The glow depends on the UV wavelength — short-wave (SW) vs long-wave (LW) — and on trace "activator" elements, so the same species can glow differently or not at all. Here are the classic fluorescent species and the colours they typically show.
Whether a mineral glows, and in what colour, comes down to activators (traces of manganese, uranium, rare earths, lead) and the lamp: many minerals react only to short-wave UV, some only to long-wave, a few to both. The famous Franklin / Sterling Hill deposit in New Jersey produces the brightest classics (willemite + calcite glowing green and red together). Always test your own specimen — locality matters as much as species.
| Mineral | Glows under | Typical glow colour |
|---|---|---|
| Fluorite | LW & SW | Blue to violet |
| Calcite | SW (mainly) | Red, pink, orange |
| Willemite | SW | Bright green |
| Scheelite | SW | Blue-white |
| Aragonite | LW & SW | Cream, pink, green |
| Hyalite opal | SW | Neon green (uranium) |
| Autunite | SW & LW | Yellow-green (uranium) |
| Hackmanite | LW | Orange (also tenebrescent) |
| Adamite | SW & LW | Yellow-green |
| Apatite | SW | Yellow to orange |
| Ruby (corundum) | LW | Red |
| Amber | LW | Bluish white |
Looking for stones that keep glowing in the dark after the lamp is off, or just curious which crystals glow? See crystals that glow (UV-reactive & glow-in-the-dark).