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A brightly fluorescent calcite scalenohedron crystal enclosed in a non-fluorescent calcite matrix. The formation of this specimen causes the internal calcite to have a zoned diamond shape.
These types of complex specimens are formed by multiple generations of calcite growth and manganese oxide minerals, with the end result producing a brightly fluorescent central calcite scalenohedron, encased in layers of essentially non-fluorescent calcite and outlined in black manganese oxide.
Color zoning can be created by changes in the nature of the fluid from which the crystal is growing. The changes could be due to temperature, pressure, and/or chemical changes. In the case of fluorescent zoning, there can be a change in the activator (what causes fluorescence) that is incorporated in the growing crystal. Source: UV Waves, v50 n6, Glenn Waychunas
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.
