|History of Sunstone
Sunstone belongs to the plagioclase feldspar group, and is named for its unusual spangled or glittery appearance. Its proper mineralogical name, however, is aventurine feldspar, named from a type of glass made with copper that was discovered by chance (from the Italian, a ventura). This is one of the rare cases where the name of a natural stone came from its synthetic simulant.
Aventurine is the name used for both a type of green quartz and a golden feldspar. Both have a metallic glittery appearance caused by inclusions. The spangled effect is known as aventurescence. Perhaps to avoid confusion, the name sunstone has been adopted in the gem trade for the feldspar, while the name aventurine (or aventurine quartz) is used for the quartz variety.
Sunstone is typically a red-brown hue, with a metallic glitter which is caused by tiny platelets of hematite or goethite. The glitter is usually gold or red, but very occasionally green or blue. We have found both opaque and transparent/translucent specimens in the market. The opaque material is cut as cabochons while the transparent material can be faceted. Some of the cabochons will display a discernible star effect and are sold under the name Star Sunstone.
Sunstone is a sodium calcium aluminum silicate, with a hardness of 6-6.5 on the Mohs scale. It has a density of 2.62-2.65 and a refractive index of 1.525-1548. It has perfect cleavage.
Sunstone deposits are found in India, Canada, Madagascar, Norway, Russia and the USA. In 1987 sunstone was named the state mineral of the state of Oregon in the USA. The Oregon sunstone is rather unique in that it is the only sunstone containing copper crystals.
Sunstone has been known for many centuries and has been discovered in Viking burial mounds. Sunstone was thought to have magical properties and could be used to invoke the energies associated with the sun. In ancient Greece, it was thought to represent the sun god, bringing life and abundance to those fortunate enough to own it. The native people in Oregon used it for trade and barter.