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Techniques for Collectors405 nm laser pointer and calcite

4th Mar 2010 01:24 UTCHenry Barwood

I bought a cheap laser pointer from China (405 nm - violet) and have found several things that fluorese in this near UV light (ruby is one). I was checking some calcites from Jones Mill, Arkansas and found that they luminesced and phosphoresced a medium pink in the beam. A quick survey showed that most of the calcites from the alkali syenites showed this same response. Expanding the investigation I tried a variety of other calcite with little luck. Finally, I tried some slices of fluorescent calcite-willemite from Franklin, NJ. The calcite was mostly dead to the violet beam, but to my surprise, there were patches that showed the same pink response as the syenite calcites.


Could this fluorescence be an activator like REE, and if so, why would small patches of it show up in the Franklin material? This has me puzzled, but until I can conduct some additional tests, I'm at a loss as to the origin of the fluorescence. Has anyone else observed this phenomenon?

4th Mar 2010 04:52 UTCJames Christopher

Yes, a lot of my calcites react this way as well, from Calumet, some calc-silicate rocks, even from Book Cliffs. Terlingua calcite shows little if any effect however. The Calumet seems to show the brightest fluorescence of everything I have, but is more orange. I do have some Franlkin material that has one or two little spots that show a response as well.

A little off subject, but I found plaster on the walls and ceiling has a short phosphorescence in a dark room with the laser.

4th Mar 2010 22:04 UTCHenry Barwood

Hi Jim,


Fascinating. I'm very curious why there are isolated activated domains in the Franklin calcites. There is obviously something odd going on. I checked a few Indiana calcites and found very little response in them. I'm glad to know that the Terlingua calcites have low response levels. I was going to see if I had a piece I could check. The plaster could be from an organic additive. Most plastics and many organic chemicals I've checked have moderately strong responses at 405 nm.

5th Mar 2010 01:25 UTCJames Christopher

Well, the Terlingua fluoresces white, not orange, although it has a couple of small patches which have faint orange.

It also looks like my XRF will finally happen!

5th Mar 2010 03:19 UTCHenry Barwood

Jim,


OK, didn't read your post about the Terlingua clacite well enough. I also discovered that some intensely SW fluorescent yellow fluorites from Bedford, Indiana also luminesce brilliantly with the 405 nm laser.I also located a box of Franklin slices and checked more calcite. The response varies from nil to fairly intense pink-orange.

14th Mar 2010 01:02 UTCJohn Attard Expert

It seems to me that a calcite should be selected to dissolve it in a weak and high purity acid (suggest freshly distilled acetic acid diluted tenfold before use) ) and see if one can isolate a residue. This after washing and drying can then be microprobed. Of course be sure there are no spurious inclusions in the calcite.


John Attard


San Diego.

4th Apr 2010 15:56 UTCJames Christopher

I found this. Excerpt from Wikipedia:

Divalent manganese, in concentrations of up to several percent, is responsible for the red or orange fluorescence of calcite, the green fluorescence of willemite, the yellow fluorescence of esperite, and the orange fluorescence of wollastonite and clinohedrite.

So maybe most Franklin Mn was bound up in the other minerals, leaving none or little for the calcite.

Furthermore, certain impurities such as iron or copper need to be absent, to prevent quenching of possible fluorescence.

Or maybe the calcite has quenchers such as those?


Divalent manganese, in concentrations of up to several percent, is responsible for the red or orange fluorescence of calcite, the green fluorescence of willemite, the yellow fluorescence of esperite, and the orange fluorescence of wollastonite and clinohedrite. Hexavalent uranium, in the form of the uranyl cation, fluoresces at all concentrations in a yellow green, and is the cause of fluorescence of minerals such as autunite or andersonite, and, at low concentration, is the cause of the fluorescence of such materials as some samples of hyalite opal. Trivalent chromium at low concentration is the source of the red fluorescence of ruby corundum. Divalent europium is the source of the blue fluorescence, when seen in the mineral fluorite. Trivalent lanthanoids such as terbium and dysprosium are the principal activators of the creamy yellow fluorescence exhibited by the yttrofluorite variety of the mineral fluorite, and contribute to the orange fluorescence of zircon. Powellite (calcium molybdate) and scheelite (calcium tungstate) fluoresce intrinsically in yellow and blue, respectively. When present together in solid solution, energy is transferred from the higher energy tungsten to the lower energy molybdenum, such that fairly low levels of molybdenum are sufficient to cause a yellow emission for scheelite, instead of blue. Low-iron sphalerite (zinc sulfide), fluoresces and phosphoresces in a range of colors, influenced by the presence of various trace impurities.


Crude oil (petroleum) fluoresces in a range of colors, from dull brown for heavy oils and tars through to bright yellowish and bluish white for very light oils and condensates. This phenomenon is used in oil exploration drilling to identify very small amounts of oil in drill cuttings and core samples.

11th Apr 2010 08:25 UTCKeith Compton 🌟 Manager

Hi


I have noted in the past that when a red laser pointer (the type used for lecture purposes) is directed at most Broken Hill (Australia) Smithsonites - particularly the rounded / globular form, that they literally glow a deep pink. Actually makes it easier to discern other asociated minerals that may be lurking on the specimens. I am not sure if this is a real fluoresecence because they don't fluoresce under the usual UV lights. It is as if the Smithsonite is reflecting the laser within itself. It doesn't have to be dark to see the effect - a typical room in softened daylight is ok.


Unfortunately I don't know enough about the physics of Fluorescence to explain what happens or why, or if in fact it is a form of fluorescence or luminescence.


Cheers

11th Apr 2010 16:49 UTCHenry Barwood

Hi Keith,


Have you ever tried other wavelength pointers to see if a similar effect is noticible? Is the glow notably different in hue than the red laser?

11th Apr 2010 19:31 UTCSteven Kuitems Expert

Henry, not all Franklin,NJ calcite is uniform in its fluorescence. The general rule is that the Mn range is from just under one % to about 6% above or below this range you tend to get diminishing response to UV sources. The idea is that the farther away from the ore body proper the Mn % diminishes and thus the UV response. There are places in the mine wall rock where you can see this in a linear approach to the ore. There is also variation within the seemingly "uniform" calcite and this is often seen under mid-wave UV light sources. Also some nearby mineral species can quench the fluorescent response from calcite locally referred to as "dead zone" calcite often from secondary intrusive veins.

Perhaps Dick Bostwick can give you a more detailed response. Hope this helps.

Steve.

12th Apr 2010 14:11 UTCKeith Compton 🌟 Manager

I haven't tried a different colour laser pointer


My initial reaction was that the light was simply refracting within the specimens - they glow a very intense red/pink - sightly different to the laser red itself. Though this may simply be the fact that the laser is penetrating the translucent Smithsonite. Bit like a red light within an eggshell.


I don't think its fluorescence itself

12th Apr 2010 21:35 UTCHenry Barwood

Keith,


If the scattered light is a different hue than the pointer, then there is likely some fluorescent component. Simple scattering would not alter the hue unless there were selective absorption going on within the smithsonite. Now if the smithsonite is highly colored, that would be a different matter.

12th Apr 2010 21:41 UTCHenry Barwood

Steven,


I know there is a lot of variation in the Mn content of the calcite, I just never realized how patchy it is until I played around with the pointer.

7th May 2010 01:39 UTCJames Christopher

Well, it's rather cool at night when at a locality with lots of orange fluorescing calcite, especially the phosphorescence. And the scorpions are almost too brightly glowing to look at, ha ha.

14th Oct 2010 16:24 UTCDonald Vaughn

well just tested several calcite specimens from different localities with a 405 nm laser for response

1. massive pink calcite from Selleck road tremolite locale in St. lawrence co. has response, but none under lw UV. seems odd

2. Yellow Lake roadcut calcite St. lawrence co. New york really bright response, have not tested with lw UV.

3. Thompson-Mckulley qy. Michigan no response.

4. massive calcite from Herkimer New york no response.

5. several calcites from Lockport Formation no response.

6. massive Calcite from Douglas lake in Tennessee no Response to laser but really bright orange response to lw UV.

the first and the last are interesting to me since the responses to the laser and the UV are opposites seems counter intuitive

14th Oct 2010 17:28 UTCBerthold Weber

... calcite from Bösenbrunn, Oelsnitz, Vogtland, Saxony, Germany (405 nm)

14th Oct 2010 18:40 UTCHenrik Friis

Henry,

405 nm is the strongest absorption band of Sm3+, which is a strong activator of photoluminescence (PL) in many minerals, e.g. apatite and leucophanite. Often minerals that shows Mn2+ luminescence with high-energy excitation (like cathodoluminescence) will actually have REE3+ activated luminescence in PL. So perhaps Sm can explain the emissions in some of the calcites.


Berthold,

That is an amazing picture


cheers


Henrik

18th Oct 2010 05:14 UTCDonald Vaughn

my Durango Apatite also fluoresces a nice warm orange

18th Oct 2010 08:03 UTCHenrik Friis

Hi Donald,


Attached is a photoluminescence spectra of five different apatites I ran some years back with 405 nm excitation. The sample "DUR" is from Durango. The emissions are from Sm3+


Henrik

19th Oct 2010 17:01 UTCDonald Vaughn

thanks Henrik, very interesting explains why most minerals excited by 405 nm have a similar response. one calcite I tested did have a bright yellow fluorescence and no phosphorescence. I wonder if this would have any practical use aside from the "neat glow".

21st Oct 2010 16:34 UTCHenrik Friis

Hi Donald,

Yes that is why many minerals will show the same luminescence, especially when you start exciting in the visible region. A lot of minerals have very broad excitation bands in the UV region, and as these can have a "tail" into the visible region your 405 nm laser might also these in addition to Sm3+. This might be the case of the calcite you mention.


And weather this has any usage or not, I believe it does. I think a lot can be learned, and new ideas created for the material science community, by looking at natural minerals. At the moment a lot of research focus on generating low energy consuming lighting in the form of LEDs, dosimetry badges or security marking all utilizing luminescence.

21st Oct 2010 17:48 UTCDonald Vaughn

I was thinking more from the mineralogy point of view. Obviously from the material science, and physics point of view many potential uses are obvious from new types of lasers to new types of "quantum dots". I'm assuming the levels of Samarium in these minerals is extremely low and I suppose its possible that this luminescence could be used for product tagging. I was even considering getting a nice clear Durango Apatite and trying to cut and polish a laser crystal from it, the A.R. coating was going to be the tough part.

I was still in the mineralogy mindset when I posted the comment about the usefulness.

21st Oct 2010 19:05 UTCHenrik Friis

Natural minerals have so many impurities influencing the luminescence, i.e. both foreign or displaced elements and vacancies, that I think it would be difficult to use them directly in a commercial way. And just because a fluorapatite from one locality works well, there are no guarantee that fluorapatite from the neighbouring locality will. Having said that, I have found that I am able to turn on different emission centres independently of each other, or all simultaneously in some natural minerals, in theory making it possible to create low costs multi frequency materials.

23rd Oct 2010 18:27 UTCDonald Vaughn

more of an experiment really I know that the distribution of Samarium is probably quite variable even in a single crystal as well as lattice distortions it probably would not work . there a Samarium doped Calcium fluoride lasers already so we know at least in some instances Samarium is used as a dopant though in a more controlled and refined manner

9th Nov 2010 07:30 UTCBerthold Weber

Here is a sample of colourless-white Opal-AN (Hyalite) which you can see fluorescing green in 405 nm Laserpointer UV light. Tubussis 22 farm, Karibib District, Erongo Region, Namibia. FOV = 6 mm.

1st Apr 2012 22:42 UTCJerryBear

I have gotten very strong responses from a 5mw 405nm laser pointer. Orange calcites of the kind from New Jersey show intense orange pink fluorescence with very brief fiery orange phosphorescense. These are stones that glow orange red under SW and hardly react to LW. In stones cotaining calcite mixed with other minerals, i get large patches of deep orange fiery fluorescence that looks just like burning coals. Some SW minerals that do not respond to LW will sometimes show some of their SW color to far violet laser light. Could this be a frequency doubling effect from using laser light? I have some corundum with chromium pebbles that are undistinguished brownish lumps under visible light and just barely present a slight reddish color under LW but will glow with a really intense fiery purplish red under the laser beam. If you look at it through light amber lenses to screen out far violet the color will look exactly like strongly illuminated gem rubies. It is interesting that only these little pen lights will bring out the hidden kinship of basically industrial grade corundum with precious gem ruby! I have seen Terlingua type calcites glow a bright whitish color under the 405nm laser light rather than the usual pink to orange LW color. To get a less burning effect, try spreading the beam with a magnifying glass. The fully concentrated beam gives the best phosphorescence but the spread beam will show the same colors. I have several so called "ultraviolet flashlights" using lED's that operate in the Far Violet range from 380nm to 405nm but they produce very poor quality mineral fluorescent effects because they give off so much visible light. On the other hand I have a true LW UV 365nm LED flashlight and it works splendidly. The laser pointer is far purer, nearly all its radiation falling into the 405nm + _ 10nm range, I also suspect the intensity and coherence of the laser beam also favors fluorescent and phosphorescent effects. I think that FV or Far violet is an exciting new expansion of the field of study for those who love fluorescent minerals. It achieves brilliant eerie effects that you can see under no other kind of light and is significantly different from longWave ultraviolet light to be in a category of its own. You should get a 5mw laser pointer to be sure to have enough power to bring out all these effects. These are the strongest laser pointers that are generally recognized as safe. Only if you stare directly into the beam for more than a few seconds will it be likely to harm your vision. The only cases known of (fortunately temporary) eye damage from 5mw lasers concerned idiots who did exactly that! You can get a 5mw 405nm laser pointer for less than $10 on Amazon. They should be in the possession of every collector of fluorescent minerals. If you take it out in the field, please do not point it up into the sky or in windows or at other people. The beam can carry for many miles.

Cheers! JerryBear

6th Apr 2012 10:39 UTCFrank K. Mazdab 🌟 Manager

Moroccan cerussite glows too with the 405 nm laser pointer, but since I'm color-blind I'll just guess it's a yellowish or greenish color... and quite bright!

6th Apr 2012 21:00 UTCHenry Barwood

Good to know about the cerussite. I've been compiling a list of species responsive to the 405 nm wavelength for an upcoming article.

7th Apr 2012 08:08 UTCFrank K. Mazdab 🌟 Manager

No problem, Henry. Three other species to add to your list are afghanite from Sar-e-Sang, some of the accompanying calcite (when you rapidly move the laser light over the calcite you get a very brief "ghosting"), and whewellite from Bilina, Czech Republic. The whewellite is phosphorescent and glows for about 10-15 seconds. The color of all three of these samples is a yellowish or greenish color I believe, but it would be wise to get a second opinion from someone with better color vision than I have. By the way, the cerussite is also slightly phosphorescent, for perhaps a second or two.

7th Apr 2012 14:56 UTCTimothy Greenland

From a practical standpoint, I found mine very useful in identifying idrialite on the Culver Baer mine dumps last May. This despite California sunshine - that stuff really beams it out!


Pink calcite from the Tankerville or Snailbeach mines in Shropshire (England) show a strong orange reaction with good persistence. If you are quick, you can almost write your name on a big chunk! Weardale fluorite works a treat, and so do most cerussites, Bage mine phosgenite and matlockite give good yellow responses. Anglesites from Broken Hill (NSW, Australia) or from Parys Mountain (Wales, UK) react quite strongly - those from Sardinia seem variable - some do; some don't, and Autunite nearly takes off on a beam of emitted photons!


There are lots of things I haven't tried yet, but that is a start...


Cheers


Tim

8th Apr 2012 01:25 UTCHenry Barwood

Thanks Frank and Timothy. So far, I have a list of over 30 minerals that luminesce with the laser and will add these to it.
 
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