Discrete and isolated thomsenolite crystals are RARE. This SUPERB specimen is LOADED with sharply terminated crystals to 6mm on finely crystalline thomsenolite and cryolite matrix. There are a couple of patches of nice cryolite crystals on the piece up to a few millimeters as well. For the last century and a half, thomsenolite specimens from Greenland have been, and continue to be, the standard for the species. Thomsenolite is a rare hydrated sodium calcium aluminum fluoride. The locality is long gone and underwater. They mined the deposit at Ivigtut below sea level, to recover the aluminum ores. Areas of the specimen are highlighted by iron oxide staining. This is a very showy and excellent piece! ex. Carnegie Museum, from the heyday here in the early 1900s.