A significant locality and species specimen of this very interesting, quite rare, crystallized aluminum species. The crystals here look like cityscape blocks, gem clear cubes rising from massive matrix (matrix and aspect looking like cryolite is supposed to, rather than like pseudocubic thomsenolites which can appear similar). An old label, probably circa 1900 or earlier, is attached to the backside. Such specimens are few and far between today, in any quality. They were mined mostly around the turn of the 1900s. From MINDAT: "A curious mineral. The colorless material seemingly disappears in water due to the proximity of their refractive indices.Historically, cryolite was used as an aluminum ore and later in the electrolytic processing of the aluminum ore bauxite....Ivigtut was the World's only mine for cryolite, used as a solvent of bauxite in aluminum production and before that to produce opaline glass. "