Discussions

💬 Home 🔎 Search 📅 Latest

╳Discussions

💬 Home 🔎 Search 📅 Latest

Groups

Recent Images in Discussions

UV Mineralsun-filtered SWUV responses

15th May 2016 21:52 UTCDon Saathoff Expert

Hello all,

Bastnaesite is easily & quickly identified by its fluorescence under un-filtered SWUV radiation and have used the technique often. In examining material collected from the nepheline syenite location, Wind Mountain in Southern New Mexico, for bastnaesite (which we found) we noticed a good number of anhedral "blebs" and spherical xl groups of an orange-yellow color with bright lemon-yellow fluorescence under the un-filtered SWUV with no fluorescence under filtered SWUV.

Has anyone else encountered this phenomenon with any other REE minerals....or minerals of any kind?

Thanks!

Don S.

15th May 2016 23:08 UTCAlfredo Petrov Manager

There was the classic test for monazite in sands, using unfiltered UV lamps. It appears to change to a bright green, but I think that was the neodymium effect, not true fluorescence, and it would apply to many different REE minerals as long as they were at least partly translucent, so it wasn't really a test for just monazite as was claimed in some prospectors' manuals.

15th May 2016 23:44 UTCDon Saathoff Expert

Thanks, Alfredo. Yes, it is the Nd effect and is limited to green and you are correct in that it is not true fluorescence but an optical effect. Gleason discusses this in his book of 1960 - I don't have the latest one yet... So, I'm still looking for some data on the bright lemon-yellow fluorescence.

Don S.

16th May 2016 00:04 UTCAlfredo Petrov Manager

If the bright lemon yellow fluorescence is not elicited by either LW, SW, or MW UV lights, only unfiltered mercury vapor lights, then that means... uh oh, looks like fluorescent collectors will need lamps with yet a fourth wavelength ;-)

16th May 2016 00:50 UTCDon Saathoff Expert

Naaah, I just flip the filter off. I do keep a Kodak yellow filter handy to remove blue when necessary.....

Don S.

16th May 2016 00:54 UTCAlfredo Petrov Manager

But then you'll never know which wavelength is eliciting your response.

16th May 2016 02:48 UTCDon Saathoff Expert

Of course you're right but I don't see the effect with LWUV or MWUV SO i'll leave the hard stuff for someone who has the equipment to measure those wavelengths. It is enough for me to know it works for many translucent to transparent cerium minerals. For some reason I suspect the lemon-yellow fluorescent effect is being caused by a constituent or trace element in what I think is monazite or another phase in the monazite group - which SHOULD show the same green effect as the bastnaesite. I guess I'll end up "biting the bullet" and send it for analysis (if I can scare up enough sample!!).

Don S.

16th May 2016 02:51 UTCAlfredo Petrov Manager

Dy causes yellow fluorescence in some fluorite, when Eu is absent - not common.

18th Jun 2016 05:15 UTCFranklin Roberts

The line causing the REM fluorescence is most likely the mercury UVC line at 184.45 nm, which is too short to pass through UV filter glass. Not all mercury lamps will pass this wavelength as it has an annoying tendency to produce ozone and will rapidly solarize UV filter glass. Many of the UVC germicidal lamps use doped quartz envelopes to block 184.45 nm due to the hazards of free ozone. Lamps intended for water purification are your best bet as they are designed to pass the ozone line.

Frank

Mindat.org is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2024, except where stated. Most political location boundaries are © OpenStreetMap contributors. Mindat.org relies on the contributions of thousands of members and supporters. Founded in 2000 by Jolyon Ralph.
Privacy Policy - Terms & Conditions - Contact Us / DMCA issues - Report a bug/vulnerability Current server date and time: April 25, 2024 17:00:57

Go to top of page