Opal, The Andalusia Mine, California
My then eight year old daughter and I explored the old Andalusia Mine tailings for fluorescents. Never before had we found so many interesting and beautiful rocks that had absolutely no fluorescence. Ironically, right next to where we parked the car was an odd boulder. We hit it with our lamp and it glowed. I cracked it up so I could get it in the car, and cracked further when we got home. This is by far the best chuck. Experts have looked at it and say it's opal. That said, I think there's some chalcedony mixed in. Just love the material, especially as no one else has anything like it.