Fluorescence is when a mineral emits visible light under ultraviolet (UV) illumination. The glow can differ under shortwave versus longwave UV and can change with trace impurities. Collectors use fluorescence to identify certain minerals and to choose specimens for UV display. Surface coatings and dirt can block the effect, so check a clean face when possible.
To document Fluorescence, record the UV type (longwave or shortwave), the glow color, and whether the effect is uniform or localized in veins, patches, or crystals. Clean a small window if the result seems weak—oils, dust, and coatings can reduce brightness. If you have both UV types, test both because some minerals respond strongly to only one. Keep a quick photo under UV with your label data so you can verify the behavior later.
Fluorescence vs. reflection Bright surfaces can reflect UV and look “lit.” True fluorescence stops when UV is turned off.
Fluorescence vs. phosphorescence Fluorescence happens under UV. Phosphorescence continues after the UV source is removed.
Fluorescence vs. dirt blocking the effect Dirt and coatings can hide fluorescence. Check a cleaned face or fresh chip.
Fluorescence vs. longwave/shortwave differences A specimen can glow under one UV type and not the other. Record which light produced the result.