Fluorescence is one of several luminescence properties that a mineral might exhibit. Other luminescence properties include: PHOSPHORESCENCE In fluorescence, electrons excited by incoming photons jump up to a higher energy level and remain there for a tiny fraction of a second before falling back to the ground state and emitting fluorescent light. In phosphorescence, the…

Two excellent introductory books about fluorescent minerals are: Collecting Fluorescent Minerals and The World of Fluorescent Minerals, both by Stuart Schneider. These books are written in easy-to-understand language, and each of them has a fantastic collection of color photographs showing fluorescent minerals under normal light and different wavelengths of ultraviolet light. They are great for learning about fluorescent…

Fluorescence has practical uses in mining, gemology, petrology, and mineralogy. The mineral scheelite, an ore of tungsten, typically has a bright blue fluorescence. Geologists prospecting for scheelite and other fluorescent minerals sometimes search for them at night with ultraviolet lamps. Geologists in the oil and gas industry sometimes examine drill cuttings and cores with UV…

Ultraviolet wavelengths of light are present in sunlight. They are the wavelengths that can cause sunburn. UV lamps produce the same wavelengths of light along with shortwave UV wavelengths that are blocked by the ozone layer of Earth’s atmosphere. Small UV lamps with just a few watts of power are safe for short periods of…

The lamps used to locate and study fluorescent minerals are very different from the ultraviolet lamps (called “black lights”) sold in novelty stores. The novelty store lamps are not suitable for mineral studies for two reasons: 1) they emit longwave ultraviolet light (most fluorescent minerals respond to shortwave ultraviolet); and, 2) they emit a significant…

You might be surprised to learn that some people have found geodes with fluorescent minerals inside. Some of the Dugway geodes, found near the community of Dugway, Utah, are lined with chalcedony that produces a lime-green fluorescence caused by trace amounts of uranium. Dugway geodes are amazing for another reason. They formed several million years ago in…

One of the first people to observe fluorescence in minerals was George Gabriel Stokes in 1852. He noted the ability of fluorite to produce a blue glow when illuminated with invisible light “beyond the violet end of the spectrum.” He called this phenomenon “fluorescence” after the mineral fluorite. The name has gained wide acceptance in mineralogy, gemology,…

Most minerals do not have a noticeable fluorescence. Only about 15% of minerals have a fluorescence that is visible to people, and some specimens of those minerals will not fluoresce. Fluorescence usually occurs when specific impurities known as “activators” are present within the mineral. These activators are typically cations of metals such as: tungsten, molybdenum, lead,…

Fluorescence in minerals occurs when a specimen is illuminated with specific wavelengths of light. Ultraviolet (UV) light, x-rays, and cathode rays are the typical types of light that trigger fluorescence. These types of light have the ability to excite susceptible electrons within the atomic structure of the mineral. These excited electrons temporarily jump up to…

What is a Fluorescent Mineral? All minerals have the ability to reflect light. That is what makes them visible to the human eye. Some minerals have an interesting physical property known as “fluorescence.” These minerals have the ability to temporarily absorb a small amount of light and an instant later release a small amount of light of…