Fluorite is a crystal

According to the Latin word fluere ("flow")
formula
Substance group
colour
Line
shine
transparency
Hardness (Mohs)
density
Cleavage
fracture

Crystal system
Crystal class
CaF2
Halides
colorless, green, yellow, purple, blue, pink
colorless
Glass gloss
transparent to opaque
4
3.1-3.2 g / cm³
perfect (octahedron)
uneven

cubic
cubic-hexakisoctahedral


Fluorite, split octahedron
Hunan, China

Antozonite from Wölsendorf, Germany

Fluorite twins Rogerley Mine, England

Fluorite from Dalnegorsk

Elmwood fluorite with healed corners

Flooring from Naica, Mexico

Phantoms from Xianghualing, China

Pink fluorite octahedron, Sommerloch, Grimsel

Calcite, fluorite, zinc blende from Elmwood
properties

Fluorite is a very common mineral worldwide that is very brittle and occurs in almost all colors. While the crystals are relatively stable, rough fluorite can crack in air. When smashed, fluorite breaks into small pieces that are shaped like an octahedron. These pieces are known as Split octahedron.

Fluorite is made up of calcium fluoride. It is very acid-resistant, it only dissolves in concentrated sulfuric acid with the formation of hydrofluoric acid. When heated on a hotplate, it starts to glow, it kicks Thermoluminescence on. Some fluorites also show one fluorescence under UV light.


Varieties

The black variety Antozonite Spreads a pungent odor when smashed, producing tiny amounts of fluorine. In 2012, researchers from LMU and TU Munich were able to detect tiny traces of elemental fluorine gas in it for the first time [Lit Schmedt / Mangstl / Kraus 2012]. The black fluorite from Wölsendorf, for example, shows this phenomenon. It smells so pungent when chipped or sawed that miners used to vomit from it [Lit Mineralienatlas]. They also called the antozonite “stinkspat”. Due to the radioactive radiation of the slightly uranium-containing antozonite, the calcium fluoride splits into fluorine and calcium. Water reacts with the fluorine to form hydrogen fluoride. This creates an oxygen radical that reacts with the oxygen in the air to form ozone. Above all, this creates the pungent smell. The fluorine is retained in small inclusions of the mineral.


Crystal forms and growth

Fluorite crystallizes in the cubic crystal system. There all basic forms appear as crystals. The most common are cubes and octahedra. Combinations of the main shapes are also very common, for example a crystal costume made of cube and octahedron. The cubes with an oblique edge contain the faces of the rhombic dodecahedron. The fluorite from Berbes on the cover picture at the top shows this phenomenon.

Twins also occur frequently, for example the penetrating twins of cubes, which are typical of the blue-green fluorites of the Rogerley Mine in England. Fluorite is also found in spherical, stalky, late, coarse or fine-grained and massive aggregates.

Disturbances during growth can cause various distortions or degenerations of the crystals. This can affect the edges, corners or surfaces. If, for example, the corners of a cube are refilled after the corner growth has been disturbed, a crystal with healed corners is obtained that is known as Carthage Corners are designated. These can have a different color or a different transparency. The purple fluorites from the Elmwood Mine in Tennessee are particularly popular when they have crystal-clear corners.

If the surface of a crystal has structural defects in the crystal lattice, surfaces twisted against each other can occur. This phenomenon is known as Tiling or as Mosaic structure. Some sites in Mexico, for example, provide these specialties.

If foreign substances are included during the first growth phase, they are formed Phantoms. If the crystal is transparent, you can see an image from the “youth phase” of the crystal.


history

Fluorspar was already used as ore by the ancient Greeks. Pliny mentions a material from which the Murrhin vessels were made. The building material myrrha for the vases and bowls is probably identical to today's fluorspar. The mineral was used in various cultures for the production of sculptures and art objects, for example among the Indians.

The mining name fluorspar goes back to its use as a flux in metal extraction. Spat is an old mining term for easily fissile minerals.


Occurrence

Fluorite used to be mined in numerous places in Germany, for example in the Black Forest in the Clara mine near Oberwolfach or in the Gottesehre mine near Urberg. The Clara mine is still active today. The Wölsendorfer district in the Bavarian Upper Palatinate is rich in fluorspar deposits. Mining there goes back to the 12th century. The area also supplies brown or black antozonite. Multi-colored fluorite is found in various places in the Ore Mountains, for example near Pöhla or Ehrenfriedersdorf. Spherical fluorite occurs on the Bellerberg near Ettringen in the Eifel.

The alpine sites such as the summer hole near Grimsel in the Swiss canton of Bern became famous for the pink fluorites. These achieve the highest prices on the collector's market. The Rogerley Mine near Weardale in England supplies green or purple cubes with interpenetrating twins that show distinct fluorescence under UV light. The purple fluorites from Berbes in Spain are often covered with light, tabular barite. Yellow fluorites, on which white calcite crystals are often found, come from the Villabona-Arlos mining area near Solis in Asturias, Spain.

The blue fluorites from Elmwood in Tennessee USA are very popular with collectors, especially when they occur together with calcite crystals. The crystals usually sit on a matrix of zinc blende. The fluorites from Dalnegorsk, Russia, are often very clear or green. Many fluorites with a wide variety of colors and shapes come onto the market from the province of Hunan in China.


use

Fluorite is an important raw material for the production of hydrofluoric acid, fluorine and fluxes for aluminum production. It is used to etch glass; clear crystals are required for lenses in optical devices, for example in telescopes and lasers. Due to their variety of colors and shapes, fluorites are sought after by collectors or they are processed into gemstones.



Fluorite from the Clara mine in the Black Forest

Globular fluorite from the Bellerberg in the Eifel

Fluorite from Pöhla in the Ore Mountains

Fluorite with siderite from Ehrenfriedersdorf in the Ore Mountains