Fluorite, also known as "Fluorspar", is a collectable, halide mineral comprised of calcium and fluorine. Fluorite occurs commonly in cubic, octahedral and dodecahedral crystals in many different colors. These colors range from colorless and completely transparent to yellow, green, blue, purple, pink or black. Purples and greens tend to be the most common colors seen. Many specimens exhibit fluorescence, or the property of fluorite to glow a different color depending upon the bandwidth of the ultraviolet light it is exposed to.
Fluorescence in fluorite is believed to be a result of impurities within fluorite known as "activators". Activators are impurities that are present within a material that have these reactions to light radiation. These common activators in fluorite are believed to be europium, yttrium, samarium and even organic material that can partially substitute for calcium during formation.
Fluorescence is a type of luminescence in which a form of radiation (photons) is introduced to a gas, solid or liquid, only to be released at a different wavelength. This incident radiation causes some electrons to become excited, resulting in this emission of electromagnetic radiation. To put it simply, fluorescence is the reflection of light off of an object in which the light was absorbed at one wave length and reemitted at a different wavelength.
The term fluorescence was mentioned in a paper by George Gabriel Stokes in 1852. Stokes elaborated on fluorites ability to change "invisible light" into blue light. Similar to opal and its opalescence, the word fluorescence was derived from the word "fluorspar", which was the common name for fluorite during this time period.
What Colors Can Fluorite Be And Why?
Fluorite can be found naturally occurring in nearly all spectrums of color. It's allochromatic, meaning it doesn't display a color when pure, though it's quite susceptible to gaining impurities that alter its apparent color. This is due to fluorites elemental structure allowing for the substitution of a variety of different impurities which interact with light in various ways.
Colorless fluorite is an indication of pure fluorite (CaF2). When fluorite contains impurities or has undergone irradiation, dependent on the impurity it can pretty much display any color.
Some fluorite specimens can contain banding of different colors. This banding is usually a result of fissures opening or closing during fluorite crystal formation, combined with subtle changes in the chemical composition of the hydrothermal fluid that's being deposited. Natural irradiation can also act as a factor in the colors that a fluorite specimen will display.
How Does Fluorite Form?
Fluorite commonly forms in veins and cavities of rocks. It's deposited by hydrothermal processes and often forms in association with metallic mineral deposits. For this reason, it is considered a "gangue mineral", meaning it forms around valuable minerals in an ore deposit, though in that setting, it is considered a commercially worthless mineral.
It has also been discovered in cavities and fractures of limestone and dolomitic rock, deposited by the same hydrothermal processes. It is a relatively common mineral that forms from common elements, so unsurprisingly it is found all around the world.
Where Is Fluorite Found?
There are fluorite deposits all over the world. The countries that are well known for their fluorite deposits are Spain, China, Austria, Canada, Switzerland, England, Morocco, France, the United States, Mexico, Namibia, Myanmar, Argentina, Switzerland, Russia and Germany.
Some locations of fluorite deposits stand out more than other for various reasons, whether it being the clarity of the crystals, the color or even the fluorites unique characteristics.
Rogerley Mine in England is one of these localities that stands out the most. First discovered in the 1970's, this well renowned deposit of fluorite contains beautiful green crystal aggregations that display a unique characteristic. While most fluorite will only show color change under UV lighting, Rogerley fluorite will change color under natural sunlight. The green crystals will display shades of purple that are visible to the naked eye.
Cave-In-Rock mining district in Hardin County, Illinois is another location that's known worldwide for producing phenomenal fluorite crystals. This area was heavily mined for years, originally for the galena (lead), however following the discovery of commercial uses for fluorite, the mining of fluorite began to boom until the majority of the mines closed in the 1990's. The fluorite crystals that came out of this area display pristine terminations and facets, as well as beautiful multi-colored specimens that often contain well defined zoning.
Beautiful, purple cubic fluorite from Harding County, Illinois
Another well known fluorite deposit and mining territory is located 43 miles South-West of Meknès, Morocco. The name of the mine is the El Hammam Mine (named after the mountain being mined) and it produces fluorite in a variety of colors, depended on the vein of collection. The El Hammam vein produces pale green colored fluorite crystals, while the Gouaida vein and the Bergamou vein produce primarily purple fluorite crystals.
The Okorusu Mine in the Otjozondjupa Region of Namibia produces vibrant purple, blue and green fluorite crystal clusters. Many of these clusters display outstanding phantoms, some of which give the fluorite a multi-colored display.
Are There Other Varieties Of Fluorite?
Yes, there are multiple varieties of fluorite, each of which have their own unique properties.
Antozonite- A variety of fluorite that contains free fluorine ions. When released via breakage/cleavage of fluorite, the fluorine reacts with water vapor to form ozone and hydrogen fluoride, which in turn results in the smell of ozone.
Blue John- A form of fluorite that's found in the UK and displays bands of purple or yellow color.
Yttrofluorite- A variety of fluorite that formed with elements of yttrium in place of calcium in fluorite's crystal lattice. Yttrium is believed to be one of the activators of fluorescence in fluorite.
Yttrocerite- A variety of fluorite in which both yttrium and cerium partially replace calcium in fluorite's crystal lattice.
Chlorophane- A form of fluorite that gives off a bright green color when heated. This reaction is known as thermoluminescence.
Can Fluorite Be Grown Synthetically?
Yes it can, in fact it is grown synthetically to help keep up with demands in the optic field. Fluorite is used in the optic field because of its low refractive index (measurement of the velocity of light as it propagates through a material), its transmittance ability of infrared and ultraviolet light, and the ability to produce clear image delineation.
Interesting Facts About Fluorite.
Fluorite naturally occurs in all spectrums of color.
Pure fluorite is colorless
Fluorite is the only common mineral with perfect cleavage in four directions.
It is a key comparative mineral of the Moh's Hardness Scale, ranking a 4 in scratch resistance.
Some fluorite displays fluorescence in natural light that is visible to the naked eye
Are There Other Uses For Fluorite?
Aside from the application of synthetic fluorite mentioned above, fluorite is an important industrial mineral that's used in metallurgical (the study of the physical and chemical behavior of metallic elements) studies, ceramic and chemical processes.
When sold in bulk, fluorite is referred to as fluorspar and comes in a variety of different grades. These different grades are; acid grade fluorspar (over 97% pure fluorite (CaF2), primarily used for chemical purposes), ceramic grade fluorspar (85 - 95% fluorite purity, used for specialty glasses and ceramics), metallurgical grade fluorspar (60 - 85% fluorite purity, used as a flux to remove impurities in molten metals), optical grade fluorspar (fluorite with exceptional optical clarity, used in cameras, telescopes and microscopes) and lapidary grade flurospar (fluorite with good color and clarity, used for application in jewelry).
Washington state has now joined over a dozen other states to put in place “shelter in place” or “stay at home” orders. While we agree this is the correct course of action, it will have a substantial impact on our business. It effectively shuts down much of our company for several weeks.
We will continue taking orders on our website and we will have a single staff member at our warehouse to facilitate shipping of these new orders. Depending on the order volume this may mean that we do experience some shipping delays, particularly with large or fragile items that require more packaging time.
These shutdowns are particularly devastating to all small businesses who don’t have significant cash reserves and rely on constant cash flow to pay their fixed expenses (payroll, rent, loan payments, etc) We hope that you will continue to support us and satisfy your fossil fix during these trying times.