Fluorescent Minerals
By Michael Corsello

Fluorescent minerals are minerals that emit visible light when activated by invisible ultraviolet light. Certain electrons and chemicals in the minerals absorb the energy from these ultraviolet light sources and jump to a higher energy state. The mineral glows when those electrons jump down to a lower energy. There are two kinds of ultraviolet light: longwave and shortwave. Longwave Ultraviolet light is also known as "black light." Shortwave Ultraviolet light is by definition of a shorter wavelength than longwave Ultraviolet light. Shortwave lamps can be very entertaining and useful to identify minerals; however it is dangerous to look at the shortwave light source as it can cause blindness and severe sunburn. Because there are two kinds of ultraviolet light, different minerals react differently under short wave ultraviolet light than under long wave ultraviolet light. Minerals can fluoresce different colors under each light. Minerals may just have a duller version of the same color under each light, and some minerals may only fluoresce under either long wave or short wave ultraviolet light. Collecting fluorescent minerals is a popular hobby and experienced collectors can use ultraviolet light for identification purposes.


White Light
Short Wave Ultraviolet Light
Long Wave Ultraviolet Light
Calcite, Willemite, & Franklinite

Sample 1 includes three different types of fluorescent minerals: calcite, willemite, and franklinite. Sample 1 was found at the Sterling Hill Mining Museum’s fluorescent mineral dump in Ogdensburg, New Jersey, September 20, 1997.

The mineral Calcite is one of the most abundant minerals on the face of the Earth. Calcite comprises roughly 4% of the Earth’s crust and can be found in numerous geologic environments. Calcite is so varied that it can exhibit a roughly 300 different crystalline forms that can be combined into a thousand different crystalline structures. In natural white light calcite appears as white and light gray crystals. When exposed to short wave ultraviolet light, calcite exhibits a very bright, deep orange color, and under long wave ultraviolet light a dull orange to red color.

Willemite is a somewhat rare zinc mineral, first discovered in huge abundance in Franklin, New Jersey. It is a small reddish brown crystal that fluoresces a brilliant, bright green under short wave ultraviolet light and a dull green under long wave ultraviolet light. Its value in New Jersey comes from its combination with other minerals, most commonly Calcite, and Franklinite. Some Willemite samples will even show phosphorescence. The bright fluorescent green of Willemite, combined with the bright fluorescent orange of the Calcite, make samples from Franklin, New Jersey very special, and a must have for any fluorescent mineral collection.

Franklinite is a non-fluorescent mineral discovered in and named after Franklin, New Jersey. In natural white light Franklinite appears as black, metallic crystals most commonly found in conjunction with Calcite and Willemite. It is an important source of both zinc ore and manganese ore.



Sample 2 is comprised mostly of a mineral called Wernerite and a micaceous material. This sample was purchased from “Mama’s Minerals” in Albuquerque, New Mexico, but was found in Quebec, Canada.

Wernerite is part of the Scapolite mineral series. The Scapolite minerals are very difficult to distinguish from one another because they differ only slightly in both density and index of refraction. It is because of the closeness in properties and varied chemistries that Scapolite is known by several other names. Wernerite is the most common alternate name for the Scapolite mineral series. It is a white crystalline rock, which fluoresces a medium yellow under short wave ultraviolet light and a bright yellow under long wave ultraviolet light.

The micaceous material also found on this sample is an amber color that fluoresces a pale green under short wave ultraviolet light. As a note, the fluorescent purple color seen in both the short wave and long wave photographs is not actually a fluorescent mineral. Most non-fluorescent minerals often reflect the purple color of the ultraviolet light back giving the illusion that the mineral is fluorescing, though it actually is not.


Diopside & Phlogopite

Sample 3 shows two fluorescent minerals: Diopside and Phlogopite. This sample was purchased from “The Enchanted Rock Garden” in Minneapolis, Minnesota, but was originally found in Ontario, Canada.

Diopside is a mineral with several varieties. The variety in this sample is ordinary Diopside and is typically white with a glassy luster. Ordinary Diopside fluoresces a pale blue color under short wave Ultraviolet light, and does not show any fluorescence under long wave Ultraviolet light.

The mineral Phlogopite is very subtle in this sample. Phlogopite is a rarer member of the mica group and is not very well known, even amongst mineral collectors. In this sample, it can be scene as an amber colored mica above the white Diopside. Phlogopite fluoresces under short wave Ultraviolet light as a very subtle yellowish, brown color amidst the pale blue of the Diopside. It too, shows no fluorescence under long wave Ultraviolet light.


Opalized Wood

Sample 4 is not actually a mineral, the same as the others are. It is actually a sample of opalized wood commonly referred to as, “Common Opal.” Opalized wood is formed when wood becomes “silicified” or filled with silica, giving it a smooth mineral like appearance. This sample was purchased from “Southwestern Minerals” in Albuquerque, New Mexico, and its origin is unknown.

As most people probably know, Opal can be a very precious and expensive gem because of the beautiful colors exhibited through opalescence. Not all Opal exhibits opalescence though, such as this sample of Common Opal. This sample has a smooth tanish white to brown color under white light, and fluoresces a medium green color under short wave Ultraviolet light. It fluoresces a much duller green under long wave Ultraviolet light.



Sample 5 is a sample of Halite. Halite typically forms in beautiful, cube shaped crystals. This particular sample, was purchased from “Southwestern Minerals” in Albuquerque, New Mexico, but was originally found in the Salton Sea area of Imperial County, California.

Halite appears naturally as a clear to rust colored crystal, which fluoresces a very beautiful bright orange color under short wave Ultraviolet light. Under long wave Ultraviolet light, Halite crystals show little to no fluorescence. Although, the image appears to show fluorescence, the Halite is actually reflecting and refracting most of the Ultraviolet light causing the illusion of and purple to red color. Another important point about long wave Ultraviolet light is that it will show every spec of dust or clothing fiber that may be on the sample. This is because of whitening agents in today’s clothing detergents.



Sample 6 is a mineral called Scheelite. This sample was purchased from F&R Associates in Sussex, New Jersey but was found at a shopping center construction site in Trumbull, Connecticut.

Scheelite is especially abundant in the United Sates and is used primarily in the production of tungsten. It is also a very popular mineral for collectors. Under white light this sample looks like a chalky, white ore, but under short wave Ultraviolet light it fluoresces a very appealing sky blue color. Under long wave Ultraviolet light, it mostly does not fluoresce, although there are a areas of pale yellow fluorescence.


Photographic Set Up

The photographic set up for this project was somewhat simple, but I did a lot of experimentation when photographing under the ultraviolet light. I shot with a Canon 30D with an ISO of 200. I used a bellows set up and a 50 mm macro lens to shoot the project.

For lighting, I used a fiberoptic light source for the white light photos, with a ping pong ball for diffusion. There were 3 ultraviolet lights I used: 1 short wave UV light and 2 long wave UV lights. The short wave UV light seen above (to the right) was a very good quality light which greatly helped with the photography aspect of the project. The 2 long wave UV lights were just cheap, basic 1 foot long black light tubes that were in portable housings for easy use.

All post-processing was done in Adobe Lightroom.

For anyone out there who may want to try something like this, you may want to try and experiment with a yellow filter to help decrease the UV color on the images. I did not use a filter though because my color turned out pretty accurate at capture.