Tucson 2021 – Benitoite

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November 17, 2019

The Fluorescent Mineral Society is putting together for Tucson 2021 what might be the largest display of fluorescent minerals ever seen. Al Liebetrau, George Polman, and Conrad North are among dozens of FMS members who have been working tirelessly at bringing this vision to life.

The Tucson Gem and Mineral Society announced over a year ago that the Big Show’s 2021 theme would be fluorescent minerals and the race to pull off a world class display has been on ever since. The buzz for Tucson 2021 continues to grow. (internal link).

I’m coordinating a benitoite display case for the exhibit. This page will record those developments. Please contact me if you have any material to loan or a piece you think I might want to buy. I’m especially interested in larger material and any stones that exhibit red fluorescence.




The 2021 TGMS Show will run from February 11th through the 14th.

More details to follow with pictures and links and all that.

Thanks in advance, Thomas

Planning on Tucson either this year or 2021? Prepare for traffic, parking, and getting around the city.  I describe here what I found three years ago. (internal link).

November 19, 2019

Ordered a vial of rough looking benitoite crystals, none of them well terminated. 50 carats or fifty small pieces. Why? As a group they may present an interesting display. I have a vial of zircon sand from Australia whose grains  light up a wonderful yellow under SW.  Arranged on a black plate they make an arresting sight. There might be a way to show off these small benitiote pieces as a contrast to the larger individual specimens in the case. We’ll see.

Crystals came from The Capistrano Mining Company:













November 22, 2019

Ordered my first large specimen for the benitoite display from Kevin Brady’s store on eBay. I wouldn’t normally buy something at this price without seeing it first in person but Brady has been an FMS member for almost 40 years and knows Al Liebetrau who is advising me on coordinating the case. I will take photographs when I get it. This benitoite specimen was bought first for its UV display, not its esthetic qualities in visible light.

Kevin Brady’s eBay store is here:


November 23, 2019

Benitoite crystals arrived today and they are glowing as I had hoped, with a variability that I will have fun learning about. Benitoite shows a wonderful powder blue under SW but I had heard about some red florescence. By getting a large number of pieces, although small, I am better able to look for this occasional occurrence and research same.

These are horrible handheld iPhone pictures taken in a barely dark room. I will eventually get my full frame sensor Nikon D90 on a tripod at night and then reshoot. I am having good luck at eliminating blue bleed at 15,000 Kelvin, an aspect of white balance. It will probably take a half hour to set up the camera, an odious chore as I am not a professional. Never-the-less, these crude photos show what I will investigate.

Unprocessed closeup photo taken with my Nikon D90. From a distance they are much fainter. The crystals in their bowl are picking up dust and I need to quiet the background.

November 27, 2019

Kevin Brady’s piece arrived the other day and I am eager to show it in its best light. Pun intended. I intend to carry out a long desired experiment, to take pictures under the same conditions with a film camera and a modern day digital camera. This will probably burn up an entire weekend to complete so it is just a matter of time, not of getting more equipment.

Right now I spend a tremendous amount of time setting up my digital camera. It means getting the right angle to shoot from, adjusting the tripod, fussing with white balance, remembering how to turn on the camera’s timer to reduce shake, and so on. And all of this is followed with much time in post, using Adobe CC’s built in camera RAW software. I have dabbled using Lightroom as well. Maybe I can reduce the time in post with film.

I’ll be using Kodak Extachrome 100 in a used Nikon film camera I got off of eBay. Dead light meter, manual focus, but that’s fine. The lab will provide me with high resolution digital files. I’m eager to see what an analog camera captures compared with a digital camera’s sensor. I suspect a digital sensor has inherent problems with UV subjects but I could be wrong.

As these handheld iPhone pictures attest, the specimen Brady provided is quite wonderful but I need to take better pictures. I am going to suggest the FMS hold a UV photography class at Tucson 2021. As a last comment, the piece displayed no red florescence.

Ordered another vial of crystals to have more material to experiment with.

November 29, 2019

Ordered two back issues of the Mineralogical Record that deal with benitoite.

Sent an e-mail to Kerry Day for advice on how to test for what I suspect is the element or elements causing the red florescence in certain benitoite pieces. Day performs qualitative EDS analysis to identify minerals. Since the mineral here is already identified, my guess is that I am looking for a trace element, not a mineral. XRF analysis may be the right choice and I have previously used Express XRF out of Bozeman, Montana. Rather than guess at the right testing method, I will rely on Day’s advice. I have sent him many mystery minerals for testing and his analysis always proves sound.

Kerry Day’s website is http://www.kaygeedeeminerals.com/

His etsy store is here:


His selection of minerals and rocks, by the way, is wonderful. Inquire if you don’t see something you are searching for. I have bought many things from him.

November 30, 2019

Kerry Day said he’d try to find out what he could with his equipment. So this morning I sent off a blue, white, and clear crystal for his analysis.  But no less a source than Wikipedia weighs in on the matter.

“Benitoite fluoresces under short wave ultraviolet light, appearing bright blue to bluish white in color. The more rarely seen clear to white benitoite crystals fluoresce red under long-wave UV light.” Ah, ha! Who needs to wait for the Mineralogical Record when you can go to Wikipedia? (That is a joke, of course.) No reference cited, of course, but both Wikipedia and web mineral.com say that benitoite steaks white. I tested a white and clear crystal on a black steak plate just now and they indeed streaked white. Great.

I’m again interested in the difference in fluorescence and I am am eager to get Kerry day’s results. My crystals respond better to MW than LW. Although the digital camera needs setting up, I may soon post some microscope photographs of the different crystals I have. The scope is far easier to take pictures with than my Nikon.

December 2, 2019

Microscope photography didn’t provide the results I wanted with the time I had to give. Another day.

I’ve been in correspondence with Al Liebetrau of the FMS. He is managing all aspects of the display cases FMS will present at The Big Show. He’s suggesting a 30″ case for the benitoite and we have been discussing lamps.

Another specimen arrived today, large but not very presentable. Only a few spots of blue under UV. Since it has so little now, and because I paid very little for it, I am going to attempt to etch it with muriatic acid. I want to see if doing so reveals any more benitoite. I am particularly interested in the lumpy area on the back. This process may take weeks as I am learning as I go.

Benitoite etching experiment from Thomas Farley on Vimeo.

Benitoite lump now sitting in a bath of HCL and water. I will attend to it every hour or so for the first few hours, seeing what develops. I am following instructions, for the most part, from The Capistrano Mining Company’s page on etching benitoite:


December 7, 2019 Remember Pearl Harbor!

Beniotite lump failing to dissolve. I may have the acid too weak. Will continue experimenting.

This project has hit a road bump, if not a complete stall. I realize now that no collector is going to want to send their specimens through the mail to loan. The only way this can work is if a collector hand carries their piece into Tuscon and then retrieves it in the same way. Otherwise, there is too much chance of breakage.

I just got a small piece in the mail two days ago. A benitoite crystal had broken off along with a neptunite crystal. I knew benitoite was fragile but this really proved the point. The rock had been packaged well, although the shipper could have done a better job. And I realize that the whole mineral world revolves around sending materials through the post. But I can’t imagine a collector trusting a prized specimen to me through the mails. In addition, I couldn’t stand the worry about not knowing if a piece would be delivered back as a broken mess.

There might be enough local collectors to fill a display case, perhaps not. I will continue my investigation into all things benitoite while I take suggestions on how to proceed with Tucson 2021. The good news is the specimen I just got does display some red fluorescence under LW.

More later.

December 10, 2015

Kerry Day has sent results. He normally tests for elements as a means of identifying a mineral. That’s in comparison with a test like XRF which is strictly a test for elements. For an example, XRF will tell you that copper exists in a rock but not which of the copper minerals is in the rock. And there could be several different copper minerals in that rock . . .

Never-the-less, Day agreed to look at what his test equipment might reveal with a specimen already identified. His tests show that there might be less sulfur in clear and white benitoite but that would have to be further proved, perhaps by quantitative analysis. It is also possible that that decrease in S  exhibited below might be responsible for the change in florescence that clear and white stones present. Still, sulfur isn’t listed  in benitoite’s formula. I haven’t read the two issues of the Mineralogical Record that discuss the gemstone, they may provide more light (UV, of course) on that matter.

Hello Thomas:

Here are your latest:

The following spectra were created with a Cambridge S100 SEM, a XR-100-CR pin diode detector and DTSA software. X-ray counts are on the vertical axis and X-ray voltage is on the horizontal axis. For various reasons peak heights are not directly comparable.

The accelerating voltage was 25 KeV. This setting exaggerates the higher voltage peaks. Detector efficiency peaks at Ca, thus, all Ca peaks are greatly exaggerated.  NA IS VERY POORLY DETECTED BY MY HARDWARE.

Some elements create more than one peak. All elements have been labeled.

My X-ray detector cannot detect Li, Be, B, C, O, N or F.

Uncoated specimens charge up under the beam and generate false peaks such as Al (1.49), Si (1.74), Cl (2.61) and Ni (7.47).  These elements are coming from the inside of my SEM chamber.  Surrounding minerals also contribute.  Any element I believe to be extraneous I did not label.

#1 Benitoite (TFarley09) Clear stone

#2 Benitoite (TFarley10) Milky white stone

#3 Benitoite (TFarley11) There appears to be an increase in S from 1 to 3.  The Cl at 2.61 KeV may or may not be real.

December 11, 2019

Confirmed with Kerry Day that sulfur is present on the labeled spectra and that his remarks on chlorine stand. I see that on the periodic table of elements that S and CI are 16 and 17, respectively. The Mineralogical Record write-ups do not mention either element. And it can’t be due to the matrix or ground mass, the crystals I sent were whole and entire. Nothing attached. Hmm.

January 1, 2020

This project is dead for now. No one has volunteered to bring a specimen to the case.  I can’t possibly afford enough specimens to fill a case. Perhaps people will come forward closer to Tucson.  Until further developments warrant, this may be my last benitoite post.

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