Jo Wicht

Who would have thought that some of the most boring looking mineral specimens could be the most spectacular under shortwave fluorescent light? Look at these three, for example…




Over time I have made a point of collecting specimens if I am aware that they fluoresce because that is fun, but often one acquires others unknowingly. Because I agreed to take some photos to supplement this edition of the MinChat, I shone my UV light over my entire mineral collection to see what I could put together. I was very surprised, and have filled up far more space than anticipated.

Above, from the top(2), we have bultfonteinite and olmeite from KMF. I think I was collecting KMF minerals at the time and chose it because that name sounded different. Its photo below certainly looks different under shortwave light. The next are two minerals I was given. The middle(2), danburite covered in calcite from Mexico and colemanite from Turkey - again none have any colour when seen in daylight. Then the last(2) is a Tsumeb cerussite on matrix that came in a collection I bought from a friend when I was first interested in minerals. Only this week did I find it glowed that marvellous red. 

What else did I find in my cabinet? A small chunk of Nevada opal (top 2) in my rejects’ drawer; Joey von Borstel once gave me that. A Moroccan with barite and cerussite on galena (middle 2), and a very scruffy little piece of apatite and fluorite from Krantzberg Mine in the Erongo region (bottom 2). The reaction from the opal was particularly surprising.




Below is a Moroccan yellow fluorite on red quartz


As well as zircons above, and Tsumeb calcites below…



Hyalite opal from the Erongo region on quartz above left, and again on schorl with aquamarine below.



And chalcedony on an unknown matrix with tiny clear crystals also from the Erongo region …


Followed by a specimen from Rosh Pinah of galena on barite, seen from both sides.



From nearby Scorpion mine, (below) the fluorescence is quite different. Hemimorphite, tarbuttite and fluorapatite are found here.



Below is my most colourful specimen, which was hand-collected at Omehani fluorite mine dumps during the first Uis Gemboree in 2008. I have shown both sides of it.



AND FINALLY, here is my specimen of willemite from Berg Aukas which fluoresces and phosphoresces – the latter being the fact that it carries on glowing after the UV light has been switched off.


For this exercise the natural light photos were taken with a flash indoors under an overhead light against a black background and with the camera set on Auto. For the UV photos the overhead light was switched off, my camera was on the Twilight setting, and my Spectrolite MinMax UV lamp was set on shortwave.  JW 

By the way, some parrots fluoresce in patches. Anyone got a friend with a parrot? Reference, to prove that I am not making this up: Parker, A. 2005. Seven deadly colours: 166-7; 171-5; 172; 178-84. London: The Free Press (Simon & Schuster.) DM 


This is a nice fluorescent specimen: check out the different views for LW and SW fluorescence, and an example of phosphorescence.