What does fluor mean?
Fluor is a traditional name for the mineral calcium fluoride (CaF₂), known to mineralogists as fluorite and to industry as fluorspar. It occurs in a striking range of colours — deep purple, emerald green, yellow, and colourless — often in well-formed cubic crystals, and it famously glows under ultraviolet light. The mineral has long been worked for practical ends: as a flux in steelmaking, where it helps impurities flow away, as the principal ore of the element fluorine, and in optically pure form for lenses that transmit ultraviolet light with minimal distortion. A banded blue-purple variety found at Castleton in Derbyshire, known as Blue John, has been carved into ornaments since at least the eighteenth century. Although 'fluor' itself now sounds somewhat dated next to 'fluorite' and 'fluorspar', the word lives on vigorously through its descendants: fluoride in toothpaste and water treatment, fluorine in chemistry, and fluorescence, which was literally named after this glowing stone.
nounFluor is the mineral calcium fluoride (CaF₂), better known as fluorite or fluorspar, valued as a source of fluorine and used in metallurgy and optics.
- The mineral calcium fluoride (CaF₂), also called fluorite or fluorspar, occurring in many colours and used as a source of fluorine, in steelmaking, and in optical equipment.
"The mine's richest seam of purple fluor was sold to a chemical works that extracted fluorine from it."
"Veins of green and purple fluor ran through the limestone quarry."
"Optical-grade fluor is prized for lenses because it bends light with little dispersion."
A standard regular plural; rarely encountered except in technical writing about multiple specimens or deposits.
"The region's fluor deposits included both green and purple varieties."
The word 'fluorescence' comes from fluor — named in 1852 after this very mineral, which glows eerie blue under ultraviolet light.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of fluor
The word comes from the Latin fluor, meaning 'a flowing', a reference to the mineral's use as a flux that makes ores melt and flow more readily in smelting. It thus shares its root with Latin-derived words such as fluent, flux, and influence. The mineral's glow later gave its name to fluorescence, described by George Gabriel Stokes in 1852, cementing fluor's place in scientific vocabulary.
Related word forms
How fluor is actually used
In modern usage 'fluor' is chiefly a technical or historical term; mineralogists usually say 'fluorite', miners and traders often say 'fluorspar'. The name survives in everyday vocabulary mainly through its derivatives such as fluoride and fluorescent.
Easily confused with fluor
Fluorine is the chemical element and gas; fluor is the calcium fluoride mineral from which it is obtained.
Fluoride is the fluorine anion or its compounds (as in toothpaste additives); fluor is specifically the mineral fluorite.