6th June 2005.
Fluorite (fluospar), a halide mineral composed of Calcium Fluoride, has been described, owing to its wide range of colours, as the most beautiful mineral, thus giving us the word fluorescent.
The mineral gives its name to the constitutive element Fluorine.(1)
Today in 2005, BBC TV2 Programme 6, was entitled ‘Seven Natural Wonders’, and explored the Blue John Cavern in Derbyshire, as it had been voted, by the people of the Midlands, one of the seven in the area.
Blue John or Derbyshire Spar is found only in the Blue John Cavern and the nearby Treak Cliff Cavern, the mineral being a type of banded Fluorite, noted particularly for its purple-blue, ornamental value. This was recognized by the 18thc industrialist, Matthew Boulton, when he said: ‘I have found a new use for Blew (sic) John.’
In opposition to the beauty of the harmless Fluorite mineral, the element Fluorine itself can be is extremely hazardous. One of its major uses is in Uranium refining for nuclear energy.
With its high reactivity, with other elements, it is impossible to keep Fluorine in its free state, except for a fraction of a second, under natural conditions.
Even the salts of fluorine (fluorides) which can collect on the inside of pipes and valves are dangerous, as they react with nearly all in/organic substances including gold and platinum.(2)
Fluorine, in combination with other Halogens, is such a strong oxidiser, that it produces the highest Oxidation States in nature. (3)
Fluorine compounds, are widely used, ranging from toxins such as Sarin, to life saving pharmaceuticals such as Efavirenz.
Most are aware of Fluoride toothpaste (Sodium Fluoride), but what about Hydrogen Fluoride used for the non-stick Teflon, Fluoropolymers (solvents and Fluorocarbons in fridges? (4)
One of the big issues has been Fluoridation of Water, going back to the 1950s, when the Mayor and Council of Andover, Hampshire, had to resign over the issue. Even now, parts of England are using water supplies with Sodium Fluoride added.(5)
The use of chemicals, as with many things in life, is thus a two-faced coin, having both beneficial or hazardous applications.
(1) The mineral Blue-John, a purple blue fluorite (fluorspar), comes from the Halide Mineral composed of Calcium Fluoride (CaF2), also called Calcium Difluoride.
Fluorine of the Halogen Group, is strongest common oxidising agent, so much so that F2 will cause metals, quartz, asbestos and even water to burst into flames.
Other good oxidisers are O2, O3 and Cl 2,which are the 2nd and 3rd most electronegative.
(2) Fluoride like other Halides is a monovalent ion (-1 Charge). Fluoride is an anion F– a reduced form of fluorine and both organic and inorganic compounds contain the element fluorine which is capable of forming compounds with all elements except Helium and Neon. The difficulty of removing an electron from fluoride ion equals the ease of addition.
A Fluorine atom oxidises other atoms by accepting one electron to fill up its outer shell to make its eight under the Octet Rule, in the process the fluorine atom is reduced. The other atom is oxidised loses one.
(3) The highest oxidation states are achieved when Fluorine combines with other Halogens forming compounds as in Bromine (V) Fluoride and Iodine (VII) Fluoride.
(4) Calcium Fluoride is an inorganic compound (CaF2) ionic compound of Calcium + Fluorine, which occurs naturally as the mineral Fluorite source of most of the world’s fluorine.
(5) Daily Telegraph, Philip Johnston, 25,3,2014, Article.
Ref: New Understanding Chemistry for A Level 3rd edit; Tef Lister and Janet Renshaw.
Ref: Wikipedia.org/ Fluorite plus Images.