s pecimen - Yellow vein - Valzergues fluorite mine
Collection Gilles Emringer.
is the most important natural fluoride. It can be found in many veins
that are often associated to granitic rocks. Due to its richness and its
colors, the fluorite has always been fascinating for the man. This mineral received
several names (Spatum vitreum, Calx fluorata...) before being called fluorite.
The commercial and industrial word is fluorspar (spathfluor in French...)
crystallographic structure, very simple, was determined by William H. Bragg. This
was done by x-rays diffraction.
Blue Fluorite - Cave-in-Rock - USA
octahedrons on calcite
of yellow fluorite cubes, disposed like a stalactite
Valzergues - Yellow Vein
class : HALIDES
system : CUBIC
Etymology : from Latin « fluere »= to flow - use in metallurgy.
Morphology : cubical, octahedral...
Color : from colorless to all colors.
Hardness : 4 (Mohs scale)
of refraction : n = 1.434
Average density = 3.13
point : 1360 °C
Transparency : all optical qualities are found (from
gem to stone).
Fluorescence : UV (long and short waves).
: in various acids, and aqueous solutions.
: often quartz.
Use : mainly in metallurgy and chemical industries.
: formation at low temperature. Especially often found in France.
-in the form of the principal mineral (see page "Mines
-in the form of a secondary mineral (see page "Other
mine is a typical exemple of hydrothermal
nice specimen from the Yellow Vein (two sides).The color is very interesting (honey-amber)
major part of crystallisations is cubic. Parallelepipedic crystals are less often
Octahedral shapes appear when the temperature in which crystallisation
can occur is higher.
At last, the fluorite can be in the form of spheres like
crystallisations coming from Mahodarry (India)…
intermediate shapes can also exist.(hexaoctahedron, tetra hexahedron…etc).
size of the crystals can reach impressive dimensions and weight (A 100 kg
single crystal was collected in the Valzergues mine - see book page 157)
can also be found (« Cumberland » twins). Epitaxies and pseudomorphosis appear
in some mines.
Hammam - Morocco
Emilio - Spain
colouring is due to the presence of various compounds in the crystal :they can
be ions (yttrium, europium…).
most widespread colors are :
violet, light purple to dark purple (Berbès …)
- blue (Beix, Burg…)
- yellow (Valzergues)
- green (La Barre…)
Crystallisations can also have an association of colors (for instance : Valzergues
where yellow fluorites have a blue-purple edging).
and light tend to make the colour
of the crystals disappear. Consequently,
it is recommended to store the samples in darkness.
notoriety of Valzergues fluorite comes from the rarety of its color.
Amber, purple and deep yellow
with blue edge...
Specimens from the "yellow vein" - Valzergues
- Aveyron - France
Rogerley fluorite is world-known for its dichroism.
Left : artificial lighting
Right : Natural ligh
Photos Jesse Fischer - private coll..
use of fluorite as an industrial mineral is recent. Until the half of the XIX
century, its interest was mainly ornamental. Then, it became industrial in the
1980s. The industrial growth goes back to 1860-1880. Currently, the fluorite is
mainly used in the following fields:
industries (manufacturing of hydrofluoric acid, thermic fluids…)
steel industries (melting in the blast furnaces…)
in fields of less economic importance.
of glass and ceramics
fluorite was primaly used in iron and steel industries, in various factories located
anywhere in France. It was exported to the United States, too.
One of the industrials...
pictures on Spathfluorminerals & MultiAxes