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Material World
Mineral · CaF2

Fluorite

The mineral that gave fluorescence its name and fluorine its existence — Mohs 4, and the source of nearly every fluorine compound made.

Ore Collectible specimen

Fluorite is calcium fluoride, and it is where fluorine comes from — essentially all of it. Hydrofluoric acid is made by treating fluorite with sulfuric acid, and everything fluorinated downstream of that, from refrigerants to non-stick coatings to the fluoride in toothpaste, traces back to this mineral.

Its older use is in the name. Fluorite was added to metal ores to make them flow more freely when melted, from the Latin fluere, to flow; the element was named after the mineral, and the mineral after what it did in a furnace.

How to identify it

Fluorite forms cubes, cleaves into octahedra, and comes in almost every colour — purple, green, blue, yellow, colourless, often several banded in one crystal. Colour is therefore useless for identifying it and is the reason it is so widely collected.

Many specimens glow under ultraviolet light, and the phenomenon was named fluorescence after this mineral. Hardness 4 and the perfect octahedral cleavage are the reliable tests.

Uses

Metallurgical-grade fluorspar is still used as a flux in steelmaking, lowering the melting point of slag so it separates cleanly.

Acid-grade fluorspar, the purer material, goes to hydrofluoric acid and from there into refrigerants, fluoropolymers, aluminium smelting and uranium processing. Optical-grade crystals are used in high-end camera and microscope lenses, because fluorite disperses light much less than glass and so produces less colour fringing.

Medium confidence Weak evidence

How we know: checked recently · only one source, so there is nothing to cross-check it against · stated directly by the source.

How this connects

Where a connection has been confirmed by an outside reference, that reference is named beside it.

is an ore of

  • Fluorine — element · the only significant source; hydrofluoric acid is made from it and everything fluorinated follows Wikidata

is a component of

  • Skarn — rock · where the intruding granite was fluorine-rich, which is also the case that favours tungsten
  • Greisen — rock · the other fluorine mineral left behind by the reaction that destroyed the feldspar
  • Epithermal vein — deposit type · common gangue in the cooler veins, and mined from them where there is enough of it

is an input to

  • Froth flotation — process · by the same fatty acid route as scheelite, and with the same difficulty separating it from the calcite alongside it

contains

Sources

  • Material World
    Our own writing
  • Wikidata
    Wikimedia Foundation · Creative Commons CC0 1.0 Universal (public domain dedication)
  • Crystallography Open Database
    COD Advisory Board / Vilnius University · CC0 — contributors place data in the public domain

Questions this page answers

Where it comes from, and what it becomes

Follow Fluorite back to what it starts as, and forward into what it becomes. Each step is a documented one — a real route material takes, not a chain of inference.

Downstream — what it becomes

  • Fluorite → is an ore of (the only significant source; hydrofluoric acid is made from it and everything fluorinated follows) → Fluorine → is an input to (as tetrafluoroethylene, which is where a substantial share of industrial fluorine chemistry ends up) → Polymerisation → produces (from ethylene; chain length and branching decide whether it is a milk bottle or a fibre) → Polyethylene → is associated with (its first significant use was radar cable insulation, and its existence was classified) → The wartime materials programmes complete chain
  • Fluorite → is an input to (by the same fatty acid route as scheelite, and with the same difficulty separating it from the calcite alongside it) → Froth flotation → is used in (the process that made low-grade disseminated sulfide deposits economic, and therefore made the modern copper industry) → Mining and quarrying → is associated with (steam pumping allowed mines below the water table, which is what made deep coal possible) → Industrial Revolution complete chain
  • Fluorite → is a component of (where the intruding granite was fluorine-rich, which is also the case that favours tungsten) → Skarn
  • Fluorite → is a component of (the other fluorine mineral left behind by the reaction that destroyed the feldspar) → Greisen
  • Fluorite → is a component of (common gangue in the cooler veins, and mined from them where there is enough of it) → Epithermal vein
  • Fluorite → is an ore of (the only significant source; hydrofluoric acid is made from it and everything fluorinated follows) → Fluorine → is used as (fluoropolymer linings resist chemicals that attack every metal) → Corrosion protection

These are the most distinct paths onward. Fluorite ends up in others besides.