Fluorite – a frozen rainbow

Fluorite (1)I’m looking at a piece of fluorite on my desk.  It measures about five inches by three, and it is basically a chunk of grey-coloured stone, quite heavy, its top surface slightly rough and bubbled in texture.  It looks almost like a miniature cobbled street – except that the cobbles are all sparkling with tiny crystals.

And half-buried in the surface of this ‘street’ are cubes of fluorite, some just less than an inch across, others much smaller;  semi-transparent like coloured glass, they contain distinct pigments of turquoise and purple which seem to swirl together without blending.

Fluorite (2)What amazes me about these crystals is their symmetry – they have such perfect edges and corners.  You feel as if you could pick them up and place dice with them.

Fluorite is composed of calcium and fluorine, and it is one of the commonest minerals in the world.  In its purple form it resembles amethyst, although it is softer than quartz and has different properties.

I was also amazed to find out how many colours fluorite can display:   in addition to greenish blue and purple, its crystals can be white, black, colourless, red, pink, deep green or bright yellow.   The colour is determined by the activities of the electrons in the mineral.   (I am not about to explain the activities of electrons:   I am still grappling with the idea that they can be in two places at once.  Thank the ever-watchable Professor Cox for that!)

Fluorite in yellow, purple and lilac; credit Hannes Grobe via Wikimedia

Fluorite in yellow, purple and lilac; credit Hannes Grobe via Wikimedia

The word ‘fluorite’ comes from the Latin, fluere, which means ‘to flow’, and refers to the fact that it was used as a flux or flowing agent in the process of smelting metals.  Amazingly, this was known as far back as Roman times:   the Romans loved to do a bit of mining, and they soon recognised the benefits of fluorite, which occurs – very conveniently – within many ore-bearing rocks.  Today, fluorite is still used in the steel-making industry, and in the production of ceramic glass, enamels and high-performance camera lenses.

What is even more interesting is the fact that fluorite glows in ultra-violet light;   this is where the word ‘fluoresce’ comes from.   Some specimens have also been found to glow in the dark for brief periods after being heated or exposed to strong sunlight.  Just imagine stumbling into a cave of glowing fluorite – no wonder crystals have been prized since the dawn of time!

Fluorite fluorescing!  Credit P Gery via Wikimedia

Fluorite fluorescing! Credit P Gery via Wikimedia

Fluorite is beautiful in any of its colour variations.  I’ve seen some lovely specimens of deep green and brilliant yellow, although most of the examples in rock and fossil shops are of the purple-and-turquoise variety.   Highly prized by collectors are the rare reds and pinks, which occur in the French and Swiss Alps.

Green variant, credit Ra'ike via Wikimedia

Green variant, credit Ra’ike via Wikimedia

In Britain, we have our own claim to fame:   at Castleton in Derbyshire, a unique type of fluorite called ‘Blue John’ has been mined for at least 100 years, originally as a by-product of the lead mining industry.   Blue John is characterised by its distinct stripes of deep purple alternating with cream or yellow, and it was so admired during the late 19th and early 20th centuries that it was used to carve a host of decorative urns and bowls.  Many of these are on display at Chatsworth House in the Peak District.

Blue John bowl, credit johnragla via Wikimedia

Blue John bowl, credit johnragla via Wikimedia

Blue John vases at Chatsworth, credit pasicles via Wikimedia

Blue John vases at Chatsworth, credit pasicles via Wikimedia

In terms of crystal healing, fluorite is believed to alleviate the symptoms of arthritis, and to fend off cold and ‘flu viruses.  It brings order to chaos, helps with concentration, and it is an effective protection against the low-level electromagnetic fields generated by computer screens.   One site describes it as ‘the genius stone’.  I think I’ll keep this piece on my desk!

Fluorite (3)

Fluorite (4)


Photos copyright © Colin & Jo Woolf unless otherwise stated

Labradorite 5Please take a look at my other features on rocks and minerals:


  1. Very interesting. There’s also an amazing collection of Blue John at Laurieston Castle in Edinburgh. My geology chum collects the stuff himself and gave a lecture there not so long ago. I think only a couple of people still carve it into goblets and the like in the UK; it’s difficult to work with, I believe. Genius stone? I could do with a bit of that.

    • I have just looked up Lauriston Castle – it looks a very interesting place to visit. I don’t think we’ve even been to that part of Edinburgh! I had no idea they had a collection of Blue John artefacts. Another place for my list! Yes, I think Blue John is difficult to work with – I think this is the only form of fluorite that can be worked, because it is so soft. As for the genius stone idea, I’m trying it already! Results expected imminently! 🙂

  2. Beautiful, interesting and mesmerising. Their inner beauty never ends, always different, unique. Very nice pictures!.

    I used to work with precious and semiprecious stones, from diamonds of the purest quality to the more common crystals spanning the rainbow colours. It is the semiprecious ones that I loved most!.

    • Thank you! How wonderful to work with precious and semi-precious stones. I would be in paradise! In another life I will be a geologist or gemologist – or maybe an archaeologist…

  3. Rocks and minerals are so fascinating…that’s probably why we always come home with a few to add to the collection! This was a great piece Jo. A great book if you want to see some eye candy and learn properties of rocks and minerals is “Gemstones of the World” by Walter Schumann. It’s a super reference book that can fit into a jacket pocket!

    • Thank you David – and I’ll look up that book right now. My jacket pockets are usually weighed down with stones, but I’m sure there’s room for a little reference book too!

  4. Delightful, fascinating and entrancing. Their inner excellence never closes, constantly distinctive, extraordinary. Extremely pleasant pictures!.

Leave a reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: