Cryolite was the chief mineral in a vast pegmatitic mass in Ivigtut, Greenland, and this ore was mined continuously for more than a century. The miners, who had sailed from Denmark, would sometimes take boulders of the transparent cryolite to use as anchors for their boats, and never quite got used to the way in which these vanished, became invisible, the instant they sank below the surface of the water.
