Here is a relatively large, twinned, sharp and lustrous crystal of the sodalite group species member, Hackmanite. It has unusually good size and luster, and sharp forms as you can see... but what really makes a rare hackmanite crystal amazing is the physical properties it can exhibit in UV light, when the electrons get charged from the UV energy and go crazy for color that is fast and shocking in its strength. Large crystals like this were found only a few times in the world of minerals, from a very few localities. It glows hot orange color, at the first hint of UV light from a lamp, but also from just sunlight. It is not only fluorescent, but also tenebrescent, in that the color stays strong after the UV is removed. This is because the excited state of the electrons from UV light persists for some time after "charging" so that it literally keeps glowing with hot neon color, even after the UV source is removed. We have tried to capture the vivid tenebrescence in the video of this specimen but it is hard to convey in video or photo how strong this effect is in person. It is actually shocking. They go from lavender purple to hot orange, and then a hot neon purple after the UV is removed. This color persists for some time, minutes to hours, depending on the strength of the light source. Hackmanite is one of the most visible instances of this effect in gems.