First Try At Fluorescent Minerals

beetleman · Post by **beetleman** » Mon Oct 16, 2006 5:46 am

I have had these Fluorescent Minerals for 12 years and have never gotten around to seeing what they look like. I finally dug up the blacklight from the basement at work and took some pictures last night. The only bad thing is somewhere I lost the key that tells me what they are.

Steve might be of service here

The lamp does not say UVA or UVB on it just blacklight, so I am going to guess UVA. Some of the minerals in the set did not show any color so I am not sure if they need the UVB.

Carl_Constantine · Post by **Carl_Constantine** » Mon Oct 16, 2006 8:34 am

Pretty cool. Guess you're not using a flash on that second shot. How long of an exposure did you use on it?

beetleman · Post by **beetleman** » Mon Oct 16, 2006 10:54 am

Sorry Carl, I have to start remembering to list the specs.

Exposure 1/5
F3
Auto focus
was in the program AE mode.
Take care.

Cyclops · Post by **Cyclops** » Mon Oct 16, 2006 11:21 am

Couple of Qs
Do all rocks flouresce?
And is the pink the fluorescent part or the blue?
Oh and how do you work out exposures when the only light source is invisible?
OK so thats 3!

beetleman · Post by **beetleman** » Mon Oct 16, 2006 1:03 pm

Well, Lets see;
1...No not all rocks glow under Blacklights.

2...It is the hot yellow-pink mineral that is Fluorescing.

3...We are still in part of the visible light spectrum using the UVA (around 400nm I think) UVB is even lower in the spectrum, and these things were glowing pretty bright

Thats about as much as I can explain it. I was letting the camera set the exposure. Ayone else want to step in with more info. "Inquiring minds want to know" Very good questions Cyclops

crocoite · Post by **crocoite** » Tue Oct 17, 2006 1:40 am

This is a site that has a pretty good explanation --> http://www.galleries.com/minerals/property/fluoresc.htm. Have a go at the quiz on the right hand side.

I suspect that your specimen is a calcite Doug.

beetleman · Post by **beetleman** » Tue Oct 17, 2006 4:33 am

Thanks for the info and great links Steve. It did look like a calcite in the matrix but I was not sure. Take care.

And Thank you Rik for the info Below. ....I figured I might as well Edit this post Instead of making a new one

rjlittlefield · Post by **rjlittlefield** » Tue Oct 17, 2006 8:40 am

beetleman wrote:2...It is the hot yellow-pink mineral that is Fluorescing.

3...We are still in part of the visible light spectrum using the UVA (around 400nm I think) UVB is even lower in the spectrum, and these things were glowing pretty bright Thats about as much as I can explain it. I was letting the camera set the exposure. Ayone else want to step in with more info. "Inquiring minds want to know"

OK, I'll give this a shot.

The mineral absorbs ultraviolet light and uses part of the energy to produce visible light, which it emits. That process is called "fluorescence".

We humans cannot see the ultraviolet light at all (which is why it's called "black light"), but black light sources usually emit some deep blue also.

What you're seeing in the picture is mostly yellow-pink light produced by fluorescence, plus (probably) blue light leaked by the ultraviolet source.

Some of the blue may be due to ultraviolet light sensed directly by the camera, but I think not much if any. Digital cameras are not very sensitive to UV by nature, and many manufacturers add explicit UV-blocking filters to reduce sensitivity even farther. See this article for a discussion of the hoops you have to jump through, to make a digital camera see UV directly.

The camera's exposure metering is based on the same light that takes the picture, which is mostly or entirely the visible pink, yellow, and blue.

--Rik

Cyclops · Post by **Cyclops** » Wed Oct 18, 2006 8:29 am

a little off topic here but but I noticed a strange phenomenon recently. I was playing around with a TV remote while my camera phone was on, and I noticed the camera could see the light quite distinctly, which is normally invisible.
Is this IR or UV?

rjlittlefield · Post by **rjlittlefield** » Wed Oct 18, 2006 9:01 am

IR. It's a fun effect. Depends heavily on the camera. My Canon PowerShot SD700 IS point-and-shoot sees the remote as very bright -- it almost blinds the camera to look directly into the remote. But my Canon 300D SLR hardly sees it at all. My ancient Sony videocamera was like the SD700 -- it could clearly see a flashing IR LED from across the room.

--Rik