Top quality large polished 'rainbow fluorite' slab with superb fine banding order textures and range of colours - makes a striking display piece

Top quality large polished 'rainbow fluorite' slab with superb fine banding textures and range of colours - makes a striking display piece

Fluorite is one of the most popular collectible minerals because of its variety of colours and well formed cubic and octahedral crystals which can be very gemmy and translucent. Fluorite crystals feature in my personal collections and you will find many specimens available on MineraliumStore. What is less appreciated is that fluorite typically forms at relatively low temperatures (by geological standards) and often grows into open cavities in limestone hosts which is how well formed crystals can grow to large size. This results in multiple layers of fluorite crystallization over extended periods of time including periods where other minerals like quartz or calcite precipitate for a while before fluorite takes over again. If the cavity doesn't fill entirely then the last fluorite event can generate the crystals we all know and collect.

However, underneath this final crystallization event there can be multiple bands of different coloured fluorite with different banding textures and thicknesses. Pure fluorite is actually colourless and transparent, and quality colourless specimens are highly sought after by specialist collectors. Colour is imparted by trace elements and inclusions which also vary with temperature and pressure of the mineralizing fluids. This gives rise to the diversity of colours with blue, green, purple and colourless being the most common colours. In rare cases this can give rise to very attractive banding which is somewhat analogous to tree growth rings except that each inorganic fluorite bands can take thousands of years to form. The best way to see and appreciate fluorite banding is with polished slabs cut perpendicular to the banding. An extra feature is that fluorite can be translucent allowing light to pass through a slab to really make the colours glow either on a windowsill or in a display cabinet.

I have a personal affinity for polished banded fluorite which is explained in the section below if you are interested. This piece is an example of top quality banded fluorite coming out of the province of Zhejiang in eastern China often sold as 'rainbow fluorite'. The range of blue, green and purple colours in different thickness bands is amazing and enhanced by bands of almost colourless fluorite which gives real translucency. Easier to look at the pictures than have me describe it. The colours really benefit from lighting in a display cabinet or some natural back lighting such as on a window shelf.

I sought out and selected these fluorite slabs very carefully so I can offer you only the highest quality which applies both to the colour banding and the mirror polish on both sides. You could find some lower cost examples on line but they wont be the same visual quality and beware of inferior polishing. I kept the cost down as much as possible through wholesale auctions where I could. Fluorite is soft and has a strong cleavage so you will always have some internal structures unlike for example agates. While I tried hard to select slabs with minimal internal crystallographic structures, you really cant avoid order them so you need to see these as features rather than imperfections.

Due to their transparency and polish it was difficult to take photographs that do the slabs real justice. Also please note I don't include videos with polished slabs due to problems with reflections and videos really don't add much for slabs.

Think of this as nature's version of stained glass. While I am clearly addicted to banded fluorite, this specimen will appeal to all collectors who simply want some display impact.

Location: Zhejiang region, China
15.5 x 12.5 x 1.0 cm (Large cabinet size)
0.50 kg
M1798

SHORT HISTORY OF POLISHED BANDED FLUORITE

The most famous banded fluorite is a variety called Blue John which comes from the Derbyshire region of England associated with historical lead zinc mines. There is significant debate as to the origin of the name which is not worth going into as no one is certain. It became popular in the 18th century when it was realized it could take a high polish and was used as inlays in items such as clocks and silverware. Some large pockets were discovered and made into rare high-end superb bowls and vases that grace many an English stately home. Blue John has a very distinctive two-tone banding with deep blue/purple and white/pale yellow bands with the blue banding often only a minor component.

While new large pockets and grand ornamental pieces are no longer available, it has remained popular mainly in jewelry. Small scale mining is now confined to the area around the village of Castleton in the Derbyshire Peak District with polishing and jewelry making done locally. The old mines and associated caves are now open as tourist attractions and the area is very popular in the summer. The locals are very protective of the term Blue John as only applicable to banded fluorite mined locally. How do I know all this - well I was born in the region and spent a lot of my early rock hounding days in the Peak District looking for both minerals and fossils which are common in the Carboniferous limestones. Later on I did my doctoral research on geological controls of Pb-Zn-Ba-F mineralisation in the same area. Mining dates back to Roman times (toxic lead was used for Roman plumbing!), and many faults that control mineralisation were later exploited by groundwater and became caves. My research combined aspects of archaeology, geology and speleology - a heady combination and I had a fantastic time. Yes I also bought my wife to be a Blue John inlaid engagement ring!

It turns out that banded fluorite that can take a high polish is not common and for many years was a niche market. Fluorite is also soft and friable, and difficult to work. Indeed modern pieces of Blue John are soaked in hot resin to stabilize them before carving and polishing. Then just over a decade ago polished banded fluorite pieces started to come out of China some of which I have to say grudgingly are equal in terms of quality and colour banding to antique Blue John. Sometimes they are marketed as 'Blue John' but this is not acceptable. A more common term for these Chinese pieces is 'rainbow banded' fluorite which is more appropriate. Compared to Blue John many of the Chinese banded fluorites do show a much broader range of colours often including greens.

Supply was initially limited and you still see some pieces being offered online at ridiculously high prices trading on the premium of genuine antique Blue John. Supply is now more plentiful and prices are reasonable so it is a good time to add some to your collection. Its hard to be certain exactly which mines are producing this new find top quality banded fluorite but most seem to be in the province of Zhejiang in eastern China. Common names assigned to specific mines are Deqing, Yacun and Yinshizan but exact locality is often not given. A local trade has arisen polishing and carving this banded fluorite into ornamental pieces like bowls and vases, and yes I own a large polished vase! They also carve animals and obelisks but that's not my thing.

Driven perhaps by nostalgia, over the last few months I have been actively seeking out and acquiring a wide range of banded Chinese fluorite slabs at reasonable prices and I am now starting to list them. They cover a wide range of sizes and different colour banding with something to hopefully suit all collecting tastes. My personal taste has always been for rare super large museum quality pieces but I learnt a valuable lesson with fluorite. Over a certain size fluorite simply isn't strong enough to support the weight of slabs unless they are extra thick in which case you tend to lose translucency. Turns out that bigger isn't always better in this case! As in all things, buy what you find attractive and ignore so called technical experts like myself.

-------Postage quoted is for Australia Post Express within Australia which typically is delivered in 2-5 days. All orders outside of Australia are sent using DHL Express which typically takes 5-8 days. Please refer to any current Covid-related shipping updates on the Shop Announcement banner as delays could occur for some countries
-------All shipments have email tracking notification, with optional signature on delivery

****If you are not happy with any aspect of your purchase let us know – our only aim is to make sure you are happy and would consider using us again in the future.

####All photos are taken using an Orangemonkie Foldio LightBox with Halo Bar LED lighting systems set at Daylight (white) 5700k using a Nikon Coolpix P520. Post Processing to ensure color balancing, cropping, etc. is done in Adobe Photoshop.
####Great care is taken to ensure accurate representative color, but it can never be 100% accurate and will also be affected by calibration of your own monitor
####Please pay attention to the scale cube and quoted dimensions – my hand is very much average size (17 cm from base of thumb to tips of fingers!)

Size Category Max dimension
Thumbnail-Size <3 cm
Miniature-Size 3-6 cm
Cabinet-Size 6-10 cm
Large Cabinet-Size 10-15 cm
Extra Large Cabinet-Size 15-20 cm
Super extra-large Cabinet-size > 20 cm