Small thumbnail piece, only about 2.4 cm, but I keep rotating it in my head anyway. Two fluorite crystals grown right into each other from the Auglaize Quarry out in Paulding County, Ohio, a spot that's been kicking out purple zoned fluorite for decades. Fluorite crystallizes in the isometric system, so it wants to be a cube, but it'll just as happily throw an octahedron or split the difference and modify the corners of one into faces of the other. When two individuals share a contact like this, you get exactly the kind of puzzle this specimen is - my eye keeps trying to figure out where one crystal actually ends and the other one starts, and the purple zoning banding through the clear outer shell only makes it trickier because the color doesn't line up cleanly with either crystal's edges. That's basically the whole appeal of twinned and conjoined fluorite for me, it's geometry doing something slightly disobedient. What gets me just as much here is the paper trail. This one is catalog number 264 in Tama Higuchi's collection, picked up in 2024 out of the Barton Friedman collection before that. That's a real chain of custody, not just a rock somebody found in a creek bed. Every serious collection builds a little archive like that, dates, prior owners, sometimes acquisition prices, and it turns a piece you could technically buy off a shelf into something with a paragraph of history attached. I get a kick out of knowing exactly whose hands a specimen passed through before it landed in front of a camera. Doesn't change the chemistry, calcium fluoride is calcium fluoride, but it changes how I look at it. Link in 🧵