Oregon is a mountaneous State at the west coast of the U.S.A., part of the Rocky Mountain belt. The mountains are mostly formed by volcanic activity, and there are many earthquakes. The reason is the plate boundary between Juan de Fuca Plate and North American Plate right off the coast. Juan de Fuca Plate is subtucted under the North American Plate, which causes continuous volcanic and tektonic activities. As a result, Oregon geology is complicated and offers numerous mineral deposits. There are patches of limestone with caves, lava tubes and various mining activities.
Oregon is famous for its Oregon sunstone, which is found in Harney County, Oregon and in eastern Lake County north of Plush. This semi-precious mineral is a plagioclase feldspar showing a brilliant spangled appearance in certain directions, an optical effect due to reflections from enclosures of red haematite. It is found in various locations on earth, but only Oregon sunstone contains inclusions of copper crystals leading to varying colours when turning the stone.