Home-grown ‘Diamonds’ - Illinois Fluorite like you've never seen it!

by Regina  Kapta

(Originally published in CentrILL Gems, the newsletter of the Central Illinois Gem & Mineral Club, March 2009.)

Tony and I spent an afternoon talking with Tom Wiesner, longtime fluorite collector and member of the CIGMC, and had the opportunity to take a look at some of the fluorite octahedrons he’s polished since the 1970’s - from a single 8 pound fluorite octahedron to tiny one inch sparkling octahedrons, nicknamed ‘diamonds’.

Tom is highly regarded as a collector, and was known as “The Fluorite Man” in Tucson for many years, although he has since sold his collection a few years ago. The Wiesner Fluorite Collection was so well known that the Springfield, Illinois State Museum featured a program of his mineral specimens. While also known for his incredible cabochons, it’s the exceptional polished fluorite octahedrons that are truly unique. While I’m trying to decide how to photograph these incredible octahedrons - what angle do you shoot when each side reveals an awesome beauty? - we asked Tom a few questions about his fascination with shaping and polishing fluorite. Fluorite usually grows as a cubic crystal, but breaks (cleaves) as an octahedron. So the octahedrons are made out of massive fluorite – not usually out of crystals. Crystals are valuable just as they are.

“I’ve made hundreds of diamonds, but not like those miners…they could make a whole diamond while I’m still trying to figure out where to make the first hit. There was one miner down there that said he started to make diamonds when he was 8 years old. It took time to perfect the technique.”

“To start a diamond, you cleave it with a chisel to rough it out, then you grind and polish it. One of the miners used a little 1/4” chisel, and some (used) clear up to a one and a half inch, or a hatchet. On the great big ones they just used a hatchet to make the diamond. One miner never made a big one and took a welding hammer and ground it down like a razor - sharp – and used that to make diamonds. He then made one of the hammers for me and that’s what I used to remake hundreds and hundreds of diamonds. To get rid of the big flat spots, I’d knock off a big flake and made little ones. It’s actually very similar to making arrowheads, but the fluorite has cleavage planes instead of conchoidal fracture. But it’s the polishing that makes the diamond.”

“You’ll know the diamond in and out by the time you finish polishing it. Each has it’s own personality. I wish I’d kept some of the ones I sold - I thought there would never be an ending to them.”

The miners made diamonds and sometimes left flat spots on it for poundage. If you shaved off the diamonds to points on all sides, you would loose a lot of the weight, and you’d end up with just really small octohedrons. Most of the time they shaved off the minimum amount, and then just left a flat instead of a point thus making more money as they sold them by the pound.

When you pick up a piece of rough fluorite, you sometimes can see what’s inside if it’s not too rough on the outside. Tom brings out flats of rough in various sizes and colors. We look at a couple to see if anything unusual is inside and what polishing might reveal. Fluorite also comes in many other colors than the common purple. Sky blue, azur blue, teal, yellow, pink and green are just some of the colors in his collection. In one box a clear white one just roughed out into an octahedron qualified – Tom didn’t have a pure white one in his collection, so that definitely was going to be polished. A bright sky blue translucent one also made the cut. These boxes were from the 1970’s and 80’s when Tom bought direct from the fluorite miners down by Cave In Rock, Illinois. Most of the octahedrons that Tom had purchased where already roughed out by the miners and often the truck drivers would carry around pieces of massive fluorite rough to work on them while they are waiting to load or unload. At one time Tom had over 4000 lbs of rough, now he has about 600 lbs of roughed out octahedrons ready to be polished. 

Tom hasn’t just worked with Illinois fluorite. He’s also polished fluorite diamonds from New Hampshire, Mexico and Pakistan. He says New Hampshire fluorite is very difficult to shape – it often won’t cleave properly and takes a long time to shape. Chinese fluorite will cleave, but not consistently, so you get mostly lopsided shapes and irregular edges.

Illinois fluorite is exceptional in that it has cleavage planes that will cleave correctly. Fluorite is not has hard as quartz, however, and the finished diamonds are sensitive to temperature change. Internal stresses within the diamond may change with age or with temperature fluctuations, and tunnels, windows and phantoms may appear and disappear over time.

Illinois fluorite can have many inclusions. Tom showed us fluorite diamonds with barite inside and marcasite hairs and nails within. Some have zones and color banding, tunnels and windows, phantoms and crystals within crystals. Some of the inclusions are cloudy white pyramids or teepee-like formations, tiny oil bubbles, crude oil drops that move - you can smell the oil when it’s polished - gas drops, water drops, barite and barite balls within the fluorite (see photo above) Even mud, where the fluorite encased the mud into the center of the diamond. We could see iridescent cleavages - shimmering like a pheasants tail. You can see original crystal structures in many of the diamonds, with growing planes and rainbow cleavages. It’s the light spectrum coming off the cleavage or growth plane because of reflected light that creates the rainbow. Also in the box was Mexican fluorite that we could see where the crystal started to grow then stopped and started again, revealing pyrolucite dendrites on the growth plane.

Fluorite forms from low temperature hot water, around 270 degrees, filling vugs. In some, the diamonds formed with marcasite or pyrite inside on a growth plane. For some reason the crystal stopped growing. The marcasite crystallized on the stopped growth plane and then the fluorite continued to grow thus encasing the marcasite within the fluorite, creating sparkles like glitter.

Incredibly, Tom shows us barite marbles that grew within the massive fluorite vein, and ended up in the middle of a diamond. Tom shows us one diamond that had an initial polish -this was done with sand paper by one of the miners, and Tom is going to finish polishing it. You really didn’t know what you were going to get from the miners because you would buy in bulk, whatever the miners thru in there. I asked him if he thought all these sky blue ones in a box came out of the same vein. “All the blue ones came out of the same mine.” Tom said. “And if I knew which miner sold them to me, I’d know what mine they came out of. The blue ones came out of the Denton or Annabelle mine. The yellows out of the Anna Belle.”
Did Tom ever run into “coontail fluorite’? He dug a sample out and explained that the miners would sell ‘cleavable’ fluorite – but it was erratic. It would cleave unevenly and the sides would be uneven. Some was broken up and attached to cards as fluorite samples.

I asked if he can still buy fluorite rough at some of the shows. “Yes, but it was a mineral specimen to them. If they’d known I was going to grind it into a diamond they probably would have passed out.”

For a change of pace, Tom has cut diamonds with uniquely curved bottoms that turn the bottoms into magnifying lenses, that enlarge the interior inclusions. He also has fluorite ground into freeform shapes that enhance the interiors - creating one of a kind works of art.

Tom also showed us the handmade fluorite spheres he made decades ago.

“I’ll tell you the history of this one - originally that was big, and I was taking the spheres to the Springfield show, and I had them rolled up in rubber carpet underlayment set in boxes. I took one out and laid it on the counter top, and then took a second one out. I wasn’t looking at the first one, and while I was unwrapping the second one, the first was unwrapping itself. When it got done, it rolled off and hit the floor, and when it hit I heard pieces fly off. Then every time it bounced another piece came off and it bounced all the way to the wall. I could put my thumb in the depressions that broke off. I had to completely redo it, and it took almost as long as to do it the first time.”

One sphere had a Saturn-like interior with phantom in it - all ground by hand. All polishing was done on a 3” wide belt. Some took 11 hours.

“I don’t have any spheres I made with the machine - I sold them as fast as I made them. I kept the ones I made by hand all out of Illinois fluorite.”

Tom has also created pyramids and eggs. He had a dealer call and requested hundreds of fluorite eggs. “I said I’d make ONE. I made it and called him back and told him “You can’t afford them”.

Oh, about that big fluorite octahedron - it weighed 11 lbs when he started. It now weights 8. This was his first one, and he wanted to have a perfect diamond - it was missing a point - Tom ground it down to a perfect diamond shape in over 11 hours. Tony and I came away with a new regard for Illinois home-grown fluorite diamonds as examples of incredible patience, awesome craftsmanship and as works of art that can stand on their own in any art gallery.

Update - sadly, Tom passed away in the summer of 2015, but left a legacy of incredible polished diamonds at home in many private collections throughout the world, and left myself and Tony with an everlasting regard for both the man and the outstanding mineral specimens we were able to view in his company.  R.Kapta 3-19-2019. 

2023 Update - Sadly Tony, my partner in this life venture, passed in 2021 after a long illness. I put the online store on hiatus for a while as I recovered and moved states. I have since reactivated the store and still have much lovely inventory to add! I have resumed my interest in this wonderful hobby, and look forward to meeting new friends in the local rock clubs. R. Kapta 3-14-23.

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About The Author

Regina Kapta is one of those multi-potentialities– lots of varied interests, but working hard to focus on one thing at a time!

Learning about geology, rock hounding and mineral collecting has naturally led to developing a online rock shop, using the foundation of years of graphic design and photography, and adding skills in e-commerce, SEO, and blogging. She has crossed a lot of boundaries, from editor of the local rock club newsletter, writing articles about minerals, setting up a rock and gem show for several years, and branching to the world of ecom.

“It’s all a work in progress, but learning keeps you young, and challenges can expand what you believe is possible! “

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