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Margarosanite is a rare calcium lead silicate mineral that shows a beautiful short wave fluorescent response that ranges from blue/white to pastel shades of purple, pink and lavender. The brown is likely prehnite.
Margarosanite from the Franklin Mine is one of the most coveted (and expensive) fluorescent minerals. First discovered in the Parker Shaft of the famous Franklin mine, in Franklin, Sussex County, New Jersey. A lesser variety of Margarosanite is also found at some of the mines in Filipstad, Varmland County, Sweden, such as Langban and Jakobsberg.
They were nicknamed "Yooperlites" which is derived from the name “yooper”. A yooper is a nickname for the Upper Peninsula natives and these fluorescent stones quickly gained fame. After data was published on these fluorescent stones, it was discovered that sodalite is the actual true mineral that is fluorescing orange.
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.
