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A very high quality piece of hackmanite with incredible tenebrescence. This is the material that put Greenland on the fluorescent mineral map. (First find sodalite) – we discovered this deposit in 2002 on our first visit. Greenland has always been known for tugtupite but this material was the reason for our first visit to this remote locale.
Hackmanite from Greenland changes its natural color upon exposure to shortwave UV very quickly. This is one of the more tenebrescent varieties from Greenland. Hackmanite from Greenland displays some of the most dramatic tenebrescence (color change) that we have seen from any place in the world. It darkens to a nice purple (see animation in photo gallery), and can be faded just as quickly using a bright UV free white light. This is best demo’d by placing the rock directly against the UV light for 30 to 60 secs, and directly against the white light for 10 to 20 secs. The change is amazing and can be repeated over and over (to our knowledge it never loses this ability). And the fluorescence ain’t that bad either!
Feldspar fluoresces a magenta under shortwave UV light. The area of green fluorescence (SW) is a uranyl activated mineral, likely analcime.
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.
