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A museum quality piece of deeply tenebrescent hackmanite. Brightly fluorescent under all wavelengths, the hackmanite also displays some phosphorescence which is unusual. Most areas of green fluorescence is the typical uranyl activated mineral found on Ilimaussaq rocks. First it’s very tenebrescent, darkening to a purplish hue after exposure to shortwave UV light. The striking tenebrescent purple hue against the white matrix provides a perfect example of tenebrescence. Combine this with the size of the specimen and you’ve got a superb piece for a collection.
The animation below shows the extreme color change (tenebrescence) after exposure to longwave and shortwave UV.
365nm UV light is often called "blacklight". Before the advent of longwave UV LEDs, blacklight fluorescent tubes, (the kinds used in hippie days to light up psychedelic posters) were the standard longwave UV light for our hobby. They were not very powerful but they did light a large area.
Enter 365nm UV LEDs
First, an animation showing the difference between the UV flashlight we recommend (365nm filtered UV flashlight) versus unfiltered 395nm UV flashlights we see many folks carrying around at shows. So. much. visible purple light. We selected a bunch of rocks as a demonstration. Took pictures of them under his flashlight without the filter and then with the filter.
A major component of rock collecting (for us) is simply getting out in nature. A buddy dragged us out to a very remote area here in middle Tennessee to hunt for fluorescent green agate. Since we consider ourselves pure "Glow Hounds" we weren't anticipating any glow rocks, just the beauty of the area, but we brought our UV lights anyway.
