Fluorite

Very common and often very colourful mineral of the Halide Class.


Multicoloured Fluorites from Argentina

Origin of name: from Latin fluere = to flow, because of its use as a flux.
The term fluorescence is also derived from Fluorite, because this mineral often very strongly displays the effect.

Synonyms and trade names: a violett/blue and yellow variety of Fluorite from Derbyshire, United Kingdom, is known as "Blue John".

Can be confused with: because of the wide range of colours, Fluorite can be confused with almost any other gemstone. However, identification by optical and physical data is quite simple and straightforward.


Three green Fluorites from Pakistan.
The two stones from the left can easily be confused with Emerald.

Localities: very common on all continents.



Opaque Fluorites from Mexico

Translucent Fluorites from Mexiko


Carved Fluorite from India

Handling: Fluorite has perfect cleavage in three directions and must be set with great care. Do not clean ultrasonically!
Furthermore Fluorite is highly susceptible to acids. No borax, no alum and above all no sulphuric acid!!
ATTENTION: produces the highly poisonous hydrogen fluoride if brought into contact with sulphuric acid (e.g. in a Rhodium bath). Even smallest concentrations of this gas can cause irritations or burns of the wind-pipe, if inhaled!

Worth knowing: the trade name "Blue John" is probably a corruption (malapropism) of the french bleu et jaune, blue and yellow.
Like with most minerals, the chemically pure form is colourless. Colours are produced by impurities. In the case of Fluorite, these mostly are rare earth minerals like Lanthanum, Samarium an Yttrium.

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