Sunstone, also known as aventurine feldspar, exhibits an optical phenomenon caused by tiny reflective inclusions of goethite or hematite.
The effect is known as 'aventurescence'.
Oregon sunstone is a fine gem-grade material that occurs in a wide variety of colours. It tends to be mostly transparent.
The inclusions in Oregon sunstone are copper.
The sunstone used to produce tumbled stones and other decorative carvings, which is opaque, is correctly known as oligoclase sunstone.
SUGILITE
