Sphalerite : ZnS

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Copyright © Christopher Clemens
minID: JP8-TGV

Sphalerite : ZnS

Copyright © Christopher Clemens  - This image is copyrighted. Unauthorized reproduction prohibited.
Dimensions: 8.7 cm x 8.0 cm x 2.4 cm
Weight: 219 g

This is an outstanding specimen of sphalerite that shows several very interesting luminescent phenomena. It was collected from an unknown mine in the area of Frisco, Beaver County, Utah. Under all wavelengths of UV light, this specimen shows a bright orange fluorescent response with orange phosphorescence, brightest under long wave. Most interesting about this piece is its triboluminescence, seen in this photograph. Triboluminescence is the property of some minerals by which they emit flashes of light as their surface is scratched or rubbed by a hard object. In the case of this sphalerite specimen, the triboluminiscence is orange, and can be induced by scratching the surface with any hard object, including a finger nail. In the photograph shown here, the point of a metal nail was used. This piece is a cut end slab, with a sawn flat surface on one side- perfect for demonstrating its triboluminescent property.

See other photographs taken under visible and UV light.

This Photo was Mindat.org Photo of the Day - 22nd Oct 2019

This photo has been shown 1106 times
Photo added:15th Jan 2017
Dimensions:5125x3961px (20.30 megapixels)
Date/Time of Photo:12th Jan 2017 23:19:11
Camera:NIKON D3300
Software:Adobe Photoshop Elements 9.0 Windows
Exposure time:1/0s
Focal Length:40mm
Focal Length (35mm film equivalent):60mm
ISO speed:6400

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Discuss this Photo

PhotosTriboluminescent POTD

22nd Oct 2019 19:57 BSTEd Clopton Expert

It's great to see a POTD with interesting, substantive content in the caption!  Thank you to Christopher Clemens for posting it, and also to the manager who flagged it as a POTD candidate when reviewing it.

22nd Oct 2019 20:52 BSTErik Vercammen Expert

More of this!

22nd Oct 2019 21:01 BSTChester S. Lemanski, Jr. Manager

You may read about triboluminescence, but few folks have actually witnessed it, particularly as significantly as this photo displays. I second Ed's comments!

22nd Oct 2019 23:58 BSTKeith Compton Manager

Very educational

23rd Oct 2019 01:21 BSTPaul Brandes Manager

It was a great selection for POTD for its educational value...

23rd Oct 2019 10:00 BSTAdolf Cortel

Absolutely amazing! Does anybody know if other sphalerites are triboluminiscent? Years ago  I prepared synthetic triboluminiscent zinc sulphide with magnanese as activator, giving the same orange color when it was softly stirred and crushed. 

23rd Oct 2019 14:06 BSTChester S. Lemanski, Jr. Manager

Sphalerites from other localities also exhibit this characteristic. General observation is that those that do all fluorescence orange = Mn activator. Perhaps others know of exceptions to this.

Much willemite from the Franklin and Sterling Mines in New Jersey also exhibits triboluminescence, but it is green. Really a nice light show when starting a drill hole into the ore underground with your cap light out. Also seen when cutting with a lapidary saw.

23rd Oct 2019 19:44 BSTJeff Weissman Expert

Chet - I'm guessing a simple drill bit on a hand-held drill will work, when I get a chance I'll try drilling some holes in a hunk of massive willemite I have. Of course, the family is going to think I'm a bit weird using power tools in the dark...

23rd Oct 2019 20:41 BSTChester S. Lemanski, Jr. Manager


I never tried it but it should work. If you do it dry the resulting powder and dust may obscure the effect.


15th Nov 2019 19:33 GMTcascaillou

You may read about triboluminescence, but few folks have actually witnessed it
Actually, everyone has seen sparks from hitting two quartz rich rocks (quartzite pebbles, flint, granite...) one against the other. Those sparks are perfect examples of the tribolumiscence of quartz. Thus cold sparks, which are completely unable to be used to light a fire, unlike what many people think...while sparks from hitting pyrite/maracasite/iron/steal with any material of equivalent or higher hardness (traditionally, flint was used because of it's availability and thoughness) are incandescence spark, thus hot sparks and able to light a fire (but the flint hitter actually isn't responsible for those, because flint isn't combustible, unlike fine sulfides or iron dust, which gets ignited by the heat of friction produced during the impact).

 Nevertheless, it's cool to have a picture illustrating the triboluminescence phenomenom. 

At some point, for the mere fun of it, I had been considering building a triboluminescence torch (one would need a crank handle mechanism, rotating two polished disks of quartz one against the other in front of a reflector material. Indeed, just rubbing energetically two flat quartzite pebbles in complete darkness will already produce quite an amount of light).

Another interesting property that I've seen demonstrated in a fun way is piezoeletricity: the device was a crank handle powered press, applying pressure to a piezoelectric crystal shaped as a cylinder, allowing to produce a small electric arc between two electrodes (and I guess the use of capacitors would allow for a bigger arc). Quite a visual demonstration of the phenomenom! (should work with quartz or tourmaline, if properly shaped)
Here's one such device:

At last, the most visually stunning way to illustrate radioactivity would be to build a cloud chamber using electrically powered 'peltier' cooling units (seriously, every radioactive minerals collector should build one of these!):

That is totally hypnotic.

16th Nov 2019 02:05 GMTAlfredo Petrov Manager

Another type of triboluminescence can be seen by peeling apart sheets of muscovite mica in the dark.

16th Nov 2019 11:01 GMTAdolf Cortel

Looking in internet on the subjet of triboluminiscence I came across a  simple demostration on triboluminescence, very suitable for children. I tried it and works well:
  Around a dozen of pieces of quartz pebbles are placed in a dry transparent plastic bottle; after adapting for a while in the dark, many flashes  are seen when the bottle is shaken.

Does anybody know if besides quartz, are there other common minerals with intense triboluminescence? I tried willemite from Franklin (scratching, crushing), without success.

16th Nov 2019 14:18 GMTAlan Pribula

Table sugar (sucrose) is triboluminesent.  Just crush a sugar cube with a pair of pliers and you'll see blue sparks.

16th Nov 2019 14:45 GMTChester S. Lemanski, Jr. Manager

Sounds like all of these data would make a wonderful and educational Mindat article. Could be linked to the glossary entry for triboluminescence.
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