A chatoyant variety of Chalcedony containing fibers of goethite and/or hematite, Binghamite / Silkstone is found only in the Cuyuna iron range (near Crosby) in Crow Wing County, Minnesota. Mining in the area uncovered deposits of the stone, but since mining operations were discontinued in the area many years ago the stone has become fairly rare and is sought after by lapidarists and gem collectors. The best binghamite compares with top pietersite for color and chatoyancy and is often referred to as “the American Pietersite”. When the stone’s pattern is arranged in level lines it is called silkstone. Binghamite and/or Silkstone is all but extinct nowadays, and even the old mine dumps and tailings have been thoroughly depleted long ago.