Fluorite (original) (raw)

Colour:

Purple, lilac, golden-yellow, green, colourless, blue, pink, champagne, brown.

Specific Gravity:

3.175 - 3.56

Name:

Named in 1797 by Carlo Antonio Galeani Napione from the Latin, fluere = "to flow" (for its use as a flux). The term fluorescence is derived from fluorite, which will often markedly exhibit this effect. The element fluorine also derives its name from fluorite, a major source of the element.

Fluorite Group.

Fluorite is found as a common gangue mineral in hydrothermal veins, especially those containing lead and zinc minerals. It is also found in some greisens, granites, pegmatites and high-temperature veins, and as a component of some marbles and other metamorphic rocks.

"(...) the F−…F− interaction has properties associated with the recently recognized type of interaction referred to as 'charge-shift' bonding".(...) integrated experimental charges for Ca2+ and F− ions are +1.40 e and −0.70 e, respectively (Stachowicz et al., 2017).

Approved, 'Grandfathered' (first described prior to 1959)

3.AB.25

3 : HALIDES
A : Simple halides, without H2O
B : M:X = 1:2

9.2.1.1

9 : NORMAL HALIDES
2 : AX2

8.4.7

8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
4 : Halides of the alkaline earths and Mg

As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.

Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.

Comment:

Dull when massive

Colour:

Purple, lilac, golden-yellow, green, colourless, blue, pink, champagne, brown.

Hardness Data:

Mohs hardness reference species

Cleavage:

Perfect
Perfect on {111}, very easy.

Parting:

Indistinct parting or cleavage on {011} at times.

Fracture:

Splintery, Sub-Conchoidal

Density:

3.175 - 3.56 g/cm3 (Measured) 3.181 g/cm3 (Calculated)

Comment:

Normal range 3.175-3.184, increasing density with rare earth element substitution.

RI values:

n = 1.433 - 1.448

Comments:

Frequently exhibits very weak anomalous birefringence, especially in cleaved, cut or pressed crystals. The birefringence is usually distributed in lamellae parallel to [001].
May show alexandrite effect.

Common Impurities:

Y,Ce,Si,Al,Fe,Mg,Eu,Sm,O,Cl,organics

Recorded ages:

Phanerozoic : 321 ± 22 Ma to 20.8 Ma - based on 6 recorded ages.

Class (H-M):

m_3_m _(_4/_m_32/m ) - Hexoctahedral

Cell Parameters:

a = 5.4626 Å

Unit Cell V:

163.00 ų (Calculated from Unit Cell)

Morphology:

Fluorite has seven main crystal forms:
the most common Are the cube {100}, octahedron {111} and dodecahedron {110}; these forms having fixed Miller indices);
and the tetrahexahedron {hk0}, trapezohedron {h11}, trisoctahedron {hhl} and hexoctahedron {hkl} (less common to quite rare crystal forms, having variable Miller indices).
Combinations of two or more of these forms are common. The cuboctahedron (combined cube and octahedron) is less common than the combination of a cube and a docecahedron, the cubododecahedron.
The faces of some crystal forms are more easily etched by nature than other faces, although this also depends on other parameters, and so none of the forms will always be smooth. Not all crystal faces will always be present, and sometimes certain faces are more developed than others, even within the same crystal form. Consequently, elongated crystals of fluorite have been observed.

Crystals distorted at times by unequal development of faces, as of {013}. Often markedly composite; minute cubes aggregated to form an octahedron at times or as an overgrowth of crystals upon the corners of an earlier formed crystal of differing habit. Massive; compact; earthy, columnar (rare), or in globular aggregates; botryoidal (rare).

For the Goldschmidt images we currently show the following habits with the crystallographic forms denoted here:
no. 1 : a cube {100}
no. 2 : an octahedron {111}
no. 3 : a dodecahedron {110}
no. 12: a cube {100}, modified by a hexoctahedron {421}
no. 45: a cube {100}, highly modified by a dodecahedron {110}, two tetrahexahedrons: {210} and {310}, and a trapezohedron {211}
no. 66: an octahedron {111}, modified by a dodecahedron {110} and a trisoctahedron {221}

Twinning:

On {111}, usually as interpenetrating cubes (e.g., Strzegom, Poland), but also as contact spinel twins (e.g. Naica, Mexico and Chumar Bakhoor, Pakistan).

Crystal Atlas:

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Epitaxy Comments:

Siderite upon fluorite with siderite [0001] parallel to fluorite [111].

Pyrite upon fluorite with parallel axes.

Quartz upon fluorite.

Discrete crystals of fluorite on ferberite from Yaogangxian mine, China (White and Richards, 2010).

Discrete crystals of fluorite on the (111) face of scheelite from the Tae Hwa mine, Korea (So et al. 1983).

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Radiation - Copper Kα

Data Set:

Data courtesy of RRUFF project at University of Arizona, used with permission.

Powder Diffraction Data:

Geological Setting:

Hydrothermal veins; cavities in sedimentary rocks; as a cementing material in sandstones; as hot springs deposits.

Japanese:蛍石

Simplified Chinese:萤石
软水紫晶

Traditional Chinese:螢石

Other Members of Fluorite Group:

Associated Minerals Based on Photo Data:

Blue under LW-UV, due to Eu2+; other colors caused by different activators (white & cream - organic matter). Red (Mapimi, Mexico), pink (Doña Ana claims, AZ), white (Sterling Hill, NJ). Green response points to ytterbium (Siddike et al. 2003).
May also be phosphorescent.

Thermal Behaviour:

Melting point 1360°C.

Notes:

May be thermoluminescent or triboluminescent.

Decomposed by H2SO4; slightly soluble in hot HCl. Slightly soluble in water (0.016 grams per liter at 18°C).

Special Storage/
Display Requirements:

Some specimens are light sensitive and become paler on exposure to light.

Health Risks:

No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

Industrial Uses:

Flux in steel making; source of fluorine

An essential component of rock names highlighted in red, an accessory component in rock names highlighted in green.

• Igneous rock
  • Normal crystalline igneous rock
    * Coarse-grained ("plutonic") crystalline igneous rock
    * Granitoid
    * Granite
    * Fluorite granite
    * Porphyritic granite
    * Trowlesworthite
    * Fluorine-rich granite
  • Exotic crystalline igneous rock
    * Ultrapotassic rock
    * Borengite
• Metamorphic rock
  • Metasomatic-rock
    * Astorite
    * Greisen
    * Secondary-quartzite

Reference List:

**Palache, Charles, Berman, Harry, Frondel, Clifford (1951) The System of Mineralogy (7th ed.) Vol. 2 - Halides, Nitrates, Borates, Carbonates, Sulfates, Phosphates, Arsenates, Tungstates, Molybdates, Ect. John Wiley and Sons, New York.**pp.29-37

Gaines, Richard V., Skinner, H. Catherine W., Foord, Eugene E., Mason, Brian, Rosenzweig, Abraham, King, Vandall T. (1997) Dana's New Mineralogy (8th ed.). Wiley-Interscience. p.1872

Czaja, M., Bodył-Gajowska, S., Lisiecki, R., Meijerink, A., Mazurak, Z. (2012) The luminescence properties of rare-earth ions in natural fluorite. Physics and Chemistry of Minerals, 39(8): 639-648.

Mao, M., Simandl, G.J., Spence, J., Neetz, M., and Marshall, D. (2016): Trace element composition of fluorite and its potential use as an indicator in mineral exploration. In: Geological Fieldwork, 2015, British Columbia Ministry of Energy and Mines, British Columbia Geological Survey Paper 2016-1, pp. 181-206. http://cmscontent.nrs.gov.bc.ca/geoscience/PublicationCatalogue/Paper/BCGS_P2016-01-09_Mao.pdf

Liu, Yang, Guo, Qingfeng, Liu, Liangyu, Zhang, Sixue, Li, Qingling, Liao, Libing (2023) Comparative Study on Gemological and Mineralogical Characteristics and Coloration Mechanism of Four Color Types of Fluorite. Crystals, 13 (1) 75 doi:10.3390/cryst13010075

Showing 88 significant localities out of 12,203 recorded on mindat.org.

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