*Note: Please make sure to right-click and print (or save) ID card located in the photo gallery for your records*
Hackmanite from Greenland offers the most striking color change (tenebrescence) we have seen from any place in the world. Most sodalite from the Ilimaussaq Complex is colored - either blue, green, gray, yellow, or some shade in between.
The sodalite fluoresces a bright orange under longwave UV light. Initially under shortwave UV light, the fluorescence is also a bright orange and turns a deeper orange as the tenebrescence sets in (the rusty color is caused by the deepening tenebrescence). The multiple hues on this specimen make it very attractive.
Upon exposure to shortwave UV the sodalite on this piece changes color to a deep purple - in seconds! Expose it to a bright white light (UV free halogen or LED spotlight held directly on the rock) and it reverts back to its natural color almost immediately - unlike the hackmanite from Afghanistan which can take days to revert back to its normal color, this piece changes back in seconds, over and over. The animation in the image gallery shows the color change (tenebrescence) after exposure to shortwave UV.
You can read more about tenebrescence in the blog posts we write up:
https://www.minershop.com/blogs/minershop-blog/what-is-tenebrescence-all-about-hackmanite-hint-its-not-fluorescence
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.
