Natural Phosphors

[old_tv_nut]

I visited the Staten Island Museum today, and discovered they have one of the best displays of fluorescent minerals I have seen.

Fluorescent rocks under ordinary visible light. From the display at the Staten Island Museum

IMG_8311cr by old_tv_nut, on Flickr

Fluorescent rock under shortwave ultraviolet light. Green spots of upper center rock are willemite, the "P1" phosphor used originally in radar scopes and color TV picture tubes (CRTs). From the display at the Staten Island Museum.

IMG_8323cr by old_tv_nut, on Flickr

Fluorescent rock under longwave ultraviolet light. Green spots in the upper center rock are willemite, the "P1" phosphor used originally in radar scopes and color TV picture tubes (CRTs). From the display at the Staten Island Museum.

IMG_8324cr by old_tv_nut, on Flickr

Fluorescent rock under combined shortwave and longwave ultraviolet light. Green spots in the upper center rock are willemite, the "P1" phosphor used originally in radar scopes and color TV picture tubes (CRTs). From the display at the Staten Island Museum. When the combined long and shortwave UV is turned off, the rock at the lower right shows a decaying phosphorescence of several seconds visibility.

IMG_8326cr by old_tv_nut, on Flickr

Closeup of the Willemite under shortwave UV:

IMG_8320cr by old_tv_nut, on Flickr

Closeup of the Willemite under longwave UV:

IMG_8316cr by old_tv_nut, on Flickr

[vintagecollect]

Nice info, would you have a close up of all phosphors w/ their names?

[newhallone]

my son thought this was really cool and then preceded to dig out all his rocks(he's 9) so we took out a black light. We did one that that had a couple specks in it. But it could have been external contamination. He had fun anyways.

[Ed in Tx]

Very cool! Reminds me of back in the early '60s, when we would pass through Weatherford TX on the way west, there was "Rockhound Museum" next to a restaurant, and the proprietor would take us into a dark room and show us the various rocks fluorescing under the two wavelengths of UV light. Fascinating stuff for an 11 year old kid (me)!

[Pete Deksnis]

Wish I had known before moving to MI about that Ogdensburg mine museum in NJ where Willemite was found. Would be an interesting place to visit and search for a trail from the mine to our 15GP22's. Heretofore I thought phosphor mines were out west.

Pete

[Electronic M]

Wow that is verry cool!

Tom C.

[old_tv_nut]

Originally Posted by vintagecollect

Nice info, would you have a close up of all phosphors w/ their names?

Sorry I don't have closeups of everything. The shots are a little shaky due to hand holding the camera, but here's what I can make out:

TOP ROW:
HALITE; FLUORITE; WILLEMITE AND CALCITE; SODALITE; CALCITE

MIDDLE ROW:
CALCITE; HARDYSTONITE (VIOLET), CALCITE (ORANGE-RED); SODALITE (ORANGE), NATROLITE (PALE BLUE-GREEN); TUGTUPITE; SCAPOLITE

BOTTOM ROW:
AGRELLITE; WILLEMITE; ARAGONITE; ESPERITE

Note the two completely different results with different calcite rocks. Fluorescence is often highly dependent on impurities in the minerals.

[Sandy G]

Aww, Bullchip...Hits done w/Mirrers, I tell ya....(grin) Seriously, this is WAY Kewl !!

[old_tv_nut]

I forgot to mention that they have a recorded narration that is synced with the display:

Sequence is visible light, shortwave UV, longwave UV, both, then all lights off, which shows several seconds of phosphorescence in the lower right rock, fading before your eyes. They do it fairly quickly, so I had to rerun it about 10 times to get all the shots including some rejects. I thought someone might complain I was overdoing it.

Plus, it now strikes me that they must have UV filters in the glass case, to prevent you from seeing the usual violet haze when strong UV is present (and of course to protect you from shortwave UV, which is dangerous) - makes the colors especially clear.

[John Folsom]

That is beautiful, Wayne. I recall seeing a similar display of fluorescent rocks at the Florida State University geoloty department many years ago.

Makes me want to go out into the wild at night with a handheld UV light and hunt for rocks.

[jhalphen]

Hello Wayne,

Thanks! for these beautiful pictures.

When one refers to longwave and shortwave UV do you know the wavelengths?

As sources, i have in mind Wood's light, commonly seen in night-clubs and also used in phony bank note & stamp detectors.

For shortwave, i am thinking of germicidal UV frequency, from memory 237 nanometers the strong ray of the Mercury atom. The tube uses a transparent Quartz envelope.

BTW, the museum wouldn't need to filter the UV to protect the public, the samples being in glass cases, ordinary glass stops all UV frequencies.

Best Regards
jhalphen
Paris/France

PS: i've seen UV LEDs recently, frequency?

[old_tv_nut]

I would refer to this wikipedia article:
http://en.wikipedia.org/wiki/Ultraviolet

The section on "black light" explains that long wavelength bulbs use a phosphor to get the required wavelength of emission, and do not need quartz bulbs; nor do they need Wood's glass unless it is desired to eliminate most visible light - so this may be what was used in the display - fluorescent tubes with Wood's glass bulbs plus extra Wood's glass filters to completely eliminate visible violet.

The small long and short wavelength lamps sold to the public that I have seen in the past definitely have some visible violet that would be visible even through the glass case. Other displays I have seen also have visible violet light showing through the glass case. That is why I suspect this display has better filtering, perhaps not in the case glass but in the bulb glass or in an extra thickness of Wood's glass added between the bulbs and the samples. I did not notice how the light sources were arranged.

By the way, I have a cataract removal and lens implant in one eye. I requested and got a UV filtering implant. Even so, I can see deeper into the violet with that eye than with the 67-year-old brown-tinted natural lens in the other eye. I saw no UV effects in either eye. Some objects are noticeably different colors in the two eyes in daylight, and even in daylight through glass. A colleague who has one UV filtering implant and one clear implant sees even stronger differences.

In WWII, it was attempted to put fluorescent paint on carrier-based planes and illuminate them with near UV so the landing officer could see them clearly at night. This had to be abandoned, as it blinded the pilots when the vitreous humour of their eyeballs fluoresced, especially the young blue-eyed pilots who had less uv absorption in their lenses.

[VintagePC]

Originally Posted by John Folsom

That is beautiful, Wayne. I recall seeing a similar display of fluorescent rocks at the Florida State University geoloty department many years ago.

Makes me want to go out into the wild at night with a handheld UV light and hunt for rocks.

Careful now... If you watch crime shows on TV at all, you know you might find more than you bargained for

[John Folsom]

I will probably take a UV light on my next backpacking trip... should be lots of rocks and no crime scenes!

[Rinehart]

Wow. The pictures are some impressive, but for something really freaky, take a look some time at a pizza under black light--it sort of looks like the surface of the Moon.