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Binghamite (also called silkstone and cyunite) is a type of agate stone found only on the Cuyuna iron range (near Crosby) in Crow Wing County, Minnesota. The formation of the stone occurs near deposits of iron ore.


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 stone has areas that are highly chatoyant similar to Pietersite or Tiger's Eye. It is a quartz with fibers of goethite usually in colors of red, gold, and black. The best Binghamite compares with top Pietersite for color and chatoyancy. When the stone's pattern is arranged in level lines it is called Silkstone. Binghamite shows crystal growth in all directions. It is named after Bill Bingham, a lapidarist, who discovered it in 1936.


  • Schumann, Walter (2007). Gemstones of the World. Sterling Publishing Company, Inc.. ISBN 1402740166. 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Binghamite". A list of authors is available in Wikipedia.
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