Fluorescence is the emission of light that some minerals exhibit when exposed to ultraviolet light. Long-wave and short-wave ultraviolet lights are commonly used to cause fluorescence. The shortwave light is higher frequency light than the long-wave light. This difference in frequency causes the electrons in the minerals to behave differently. Thus, the same mineral may emit a different color fluorescence under long-wave ultraviolet light than under shortwave ultraviolet light. As incoming ultraviolet light is absorbed by the mineral, weakly held electrons within the crystal are “excited” by the light to higher energy levels. As the electrons settle back to their original state, energy is given off as fluorescence.

1- Turritella agate is found in the Green River Formation of Wyoming. This translucent to semi-transparent gem contains large fossil snails, which contrast beautifully with the brownish agate. The snails belonged to the now-extinct species, Elimia tenera, ancient freshwater snails that thrived around 50 million years ago. The agate itself ranges from brown to black, while the fossilized snails appear as white to tan inclusions. Under shortwave and longwave UV fluorescence, this specimen reflects white cream and white, respectively.

2- Wernerite is typically pale gray to white. It is especially interesting to fluorescent mineral collectors because it brightly fluoresces under long-wave UV light. Most fluorescent minerals respond best under shortwave UV, so Wernerite long-wave fluorescence stands out. This specimen can be found in Canada and under shortwave and longwave UV fluorescence, this specimen reflects bright yellow and yellow, respectively.

3- Willemite is usually associated with limestone and often forms as an alteration of previously existing sphalerite ore. It naturally occurs in a variety of colors, including gray, black, flesh-red, pink, and dark brown. This specimen can be found in Canada and under shortwave and longwave UV fluorescence, this specimen reflects bright green and light green, respectively.

4- Septarian Nodule formed between 50 and 70 million years ago. They originated as fossilized mud bubbles. They consist of at least two minerals. The exterior is typically gray mudstone, while the interior varies in color from white to brown, sometimes with hints of orange. Their unique patterns make them popular among collectors. Septarian nodules can contain minerals like barite, quartz, or even a hollow center lined with large crystals. This specimen can be found in Utah and under shortwave and longwave UV fluorescence, it reflects cream white and cream.

5- Travertine is a type of sedimentary rock formed by the precipitation of carbonate minerals from groundwater. It often occurs in and around hot springs, caves, and limestone deposits. The name travertine comes from the Italian word “travertine” which means “a place where water flows”. Travertine is a beautiful natural stone with a light color, often used for both aesthetic and practical purposes. This specimen can be found in New Mexico and under shortwave UV fluorescence, it reflects cream white.

6- Tremolite is a silicate mineral belonging to the amphibolite group. It is formed by the metamorphism of sediments rich in dolomite and quartz. Tremolite can be colorless, pale green, brown, yellow, or gray. This specimen can be found in New Jersey and under shortwave and longwave UV fluorescence, this specimen reflects white pink, and orange, respectively.

7- Scheelite is an important ore of tungsten and is also known as wolfram. The mineral was originally named after Swedish chemist Carl Wilhelm Scheele (1742-1786). Its hardness is 4.5 - 5 on the Mohs scale. Well-formed scheelite crystals are sought by collectors and can be fashioned into gemstones when free of flaws. Under short-wave UV fluorescence, this specimen reflects white and can be found in Colorado.

8- Selenite Rose, also known as gypsum rose or sand rose, is a unique form of selenite, a crystalline variety of the mineral gypsum. Its distinctive appearance is characterized by delicate rosette formations resembling the petals of a blooming desert flower. These beautiful formations are created when sand particles become embedded in the selenite blades, and over time, water helps shape them into their signature rosette shapes. Selenite can be found in arid desert regions around the world. This specimen can be found in Mexico and under shortwave and longwave UV fluorescence, this specimen reflects white tan.

9- Semi-opal, sometimes referred to as half-opal, refers to a variety of common opals. Unlike precious opals, semi-opal lacks the mesmerizing play of color seen in opals like black opals or crystal opals. Instead, it typically exhibits a translucent to opaque appearance with a range of body colors, which may include white, light gray, or other pale hues. Under both shortwave and long-wave UV fluorescence, this specimen reflects green and green orange, respectively, and can be found in Wyoming.

10- Chalcedony is a fascinating mineral and a cryptocrystalline form of silica, composed of very fine intergrowths of quartz and morganite. It typically has a waxy or glassy luster and can be semitransparent or translucent. It's been used for centuries in jewelry, carvings, and decorative objects. Under both short-wave and long-wave UV fluorescence, this specimen reflects green and light green respectively, and can be found in South Dakota.

11- Fluorite, also known as fluorspar, belongs to the halide mineral family. Although pure fluorite is colorless and transparent, with impurities, it often gives its vibrant colors such as purple, lilac, green, pink, and brown. For those reasons, fluorite is very popular for jewelry and decorative objects. Under both short-wave and long-wave UV fluorescence, this specimen reflects blue and light blue respectively, and can be found in Mexico.

12- Hackmanite is a rare and intriguing mineral with unique properties. It is a variety of sodalite, composed of sodium aluminum and silicate chloride. What sets it apart is its remarkable color-changing behavior. It exhibits tenebrescence, meaning it changes color when exposed to sunlight or ultraviolet rays. Its original color is violet, which can vary from very pale to dark violet. Under both short-wave and long-wave UV fluorescence, this specimen reflects orange and light orange respectively, and can be found in Canada.

13- Aragonite is a carbonate mineral and one of the most common naturally occurring crystal forms of calcium carbonate. It is formed through biological and physical processes, including precipitation from marine and freshwater environments. It is found in various geological settings such as sedimentary, metamorphic and igneous rocks. Under both short wave and long wave UV fluorescence, this specimen reflects white in color and can be found in Florida.

14- Bituminous Coal, also known as black coal, is sedimentary in origin and contains a tar like substance called bitumen or asphalt. It can be black or dark brown and is primarily used for electrical power generation and in the steel industry. Under both short wave and long wave UV fluorescence, this specimen reflects blue white in color and was found in Utah.

15- Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate. It is found extensively in sedimentary rocks, especially limestone. Limestone, composed mostly of calcite, has numerous uses in construction, agriculture and industry. Large calcite crystals are also used in optical equipment. Its Mohs hardness is 3, making it a defining mineral on the hardness scale. It is typically colorless or creamy white, but it may have shades of brownish colors. Under shortwave UV fluorescence, this specimen reflects cream pink in color and can be found throughout the USA.