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Techniques for Collectors405 nm laser pointer and calcite
4th Mar 2010 01:24 UTCHenry Barwood
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
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
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
It also looks like my XRF will finally happen!
5th Mar 2010 03:19 UTCHenry Barwood
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
John Attard
San Diego.
4th Apr 2010 15:56 UTCJames Christopher
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
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
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
Perhaps Dick Bostwick can give you a more detailed response. Hope this helps.
Steve.
12th Apr 2010 14:11 UTCKeith Compton 🌟 Manager
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
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
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
14th Oct 2010 16:24 UTCDonald Vaughn
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
14th Oct 2010 18:40 UTCHenrik Friis
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
18th Oct 2010 08:03 UTCHenrik Friis
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
21st Oct 2010 16:34 UTCHenrik Friis
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 still in the mineralogy mindset when I posted the comment about the usefulness.
21st Oct 2010 19:05 UTCHenrik Friis
23rd Oct 2010 18:27 UTCDonald Vaughn
9th Nov 2010 07:30 UTCBerthold Weber
1st Apr 2012 22:42 UTCJerryBear
Cheers! JerryBear
6th Apr 2012 10:39 UTCFrank K. Mazdab 🌟 Manager
6th Apr 2012 21:00 UTCHenry Barwood
7th Apr 2012 08:08 UTCFrank K. Mazdab 🌟 Manager
7th Apr 2012 14:56 UTCTimothy Greenland
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
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Privacy Policy - Terms & Conditions - Contact Us / DMCA issues - Report a bug/vulnerability Current server date and time: April 26, 2024 14:17:41