Collecting fluorescent minerals

Clay Carkin (USA)

Compared to the collection of fossils and traditional mineral specimens, the hobby of collecting fluorescent minerals is in its infancy. Even though Sir George Stokes discovered the property of fluorescence in the early 1800s (from the blue glow of fluorite in sunlight), it was not until the 1940s that portable ultraviolet (UV) lamps became available to the public. During WWII, the United States needed the metal tungsten, which is present in the mineral scheelite. Mr Thomas S Warren (president and founder of Ultra-Violet Products Inc.) invented a portable ultraviolet lamp to help prospectors locate deposits of this strategic metal. In doing so, not only did Mr Warren advance the commercial application of UV lights, he also made the lamps available to hobbyists.

Today, there are around eight manufacturers of ultraviolet lamps. The lamps come in all shapes and sizes, but all have a source of either short wave, mid wave or long wave UV light. You can purchase an AC lamp for home use, or a DC lamp with a 12 volt battery pack to take into the field. Collecting fluorescent minerals in daylight hours is possible, but a tarpaulin or gas grill cover is necessary if you are going to try. However, the real thrill is in night collecting, where the full effect of the UV rays can be observed without the brilliance of sunlight to obscure a mineral’s fluorescence.

If you decide to collect your own fluorescent minerals in the field, it is wise to carefully plan your explorative forays:

1. Visit your collecting site in daylight hours. Plan your walking route in, or around, dumps at quarries and mines and make notes of cliffs, pits and other dangers.
2. Dress appropriately for the weather conditions and wear stiff hiking boots.
3. Take a backup battery for your lamp as well as spare flashlight batteries for your torch. Be sure to have charged your main, portable UV light battery the day before.
4. Collect with a friend. He or she can scan the collecting site with the lamp as you pick out the specimens.
5. Let someone know where you are going and when you expect to return.
6. Take a mobile phone, just in case.
7. Get permission (if necessary) to collect on private land.

I have collected minerals for years, but have only recently been bitten by the fluorescent mineral bug. I have had a long and short wave AC lamp for a while that I have used for demonstrations of fluorescent minerals in my science class, but it was not until this year that I purchased a portable DC lamp with a 12 volt battery pack. Having previously purchased all my fluorescent minerals from dealers, I felt it was time to get out and collect my own (free) specimens.

This is the story of my first fluorescent mineral collecting trip …

After making many phone calls, writing letters and researching ultraviolet lights on the Internet, I made a decision to purchase a ‘Way Too Cool’ DC UV short and long wave lamp. When the lamp arrived, I was eager to try it out at a local mine, but finding time in a busy school schedule turned out to be difficult. Finally, I had a chance to try out my new UV light and, with a newly purchased tarpaulin to cover myself up, a rug to sit on, a new DC lamp and a fully charged battery, I was ready to do some serious collecting.

Day one (Saturday)

Not far from Harpswell, Maine (where I live) in the town of Topsham, there are dozens of historic pegmatite mines (seven in a row, over a short hike). My plan was to make an afternoon trip to scope out the mines. At the first mine (Consolidated #1), I found a level area in the waste material dump and proceeded to cover myself with my tarpaulin. I discovered that this was translucent when used in a single layer, so I doubled it over and found there was still too much light getting in. After reducing the overall size of the tarpaulin again, there was now light slipping in from under its sides! Finally, I managed to create a semi-dark environment and saw a few yellow-green glowing spots of hyalite on some rocks. After all the preparation, work and expense, I had seen my first fluorescent minerals in the field. What a rush! It was clear that this locality might have the potential for finding more fluorescent minerals, if only it were darker.

Day two (Sunday)

A large snowstorm (in Maine we call them ‘northeasters’) was forecast to hit the following day. Therefore, I had to focus all my efforts tonight as it was possible that there would be so much snowfall that it would be spring before I could get out to the mine and collect again. My day was full of errands and Christmassy things to do. As the hours ticked by, I became increasingly impatient for nightfall. At last, the sun set and off I rushed to the mines in Topsham. Obviously, I had scoped out the area on Saturday so I knew where to go (and of course where not to go). When I got to the Consolidated #1 mine dump, I turned on my lamp and, much to my surprise, fluorescing green spots showed up all over it. Finding fluorescent minerals was going to be like shooting fish in a barrel! After a half hour of collecting, I had all I could carry, along with a broad smile of satisfaction adorning my face. It was so easy, so exciting, and was my first really successful fluorescent mineral collecting trip.

It was time to move on and check out a construction site in Topsham where blasting in a ledge had been carried out to make room for some underground tanks. I thought that this area may be part of a larger pegmatite body and, therefore, hyalite might be present here too. When I arrived at the site,  streetlights illuminated the area, but there were some dark shadows falling from the edges of the pit. I climbed down and turned on my lamp. Once the purple glow of the lamp struck the ledge, those fluorescent green spots showed up again – more free samples for the taking and only a 40-foot walk from my car.

Day three (Monday)

The northeaster was in full force as advertised. The weather was so bad that many businesses were closed and, of course, there was no school that day! There was already six inches of snow on the ground and more on the way. However, I had many self-collected specimens to examine in the warmth of my basement and looking out the window at the falling snow, it appeared that collecting any more fluorescent minerals would have to wait until spring!

Fluorescent mineral gallery

Further reading

Warren, Gleason, Bostwick and Verbeek, 1995. Ultraviolet Light and Fluorescent Minerals. Published by Thomas Warren. Schneider, Stuart, 2004. Collecting Fluorescent Minerals. Schiffer Publishing Ltd.

Collecting groups and information

Fluorescent Mineral Society, Jan Wittenberg, President, 23101 Valerio Street, West Hills, California, 91307.