History of Sunstone
Sunstone belongs to the plagioclase feldspar group, and gets its name from its unusual spangled or glittery appearance. Its proper mineralogical name, however, is aventurine feldspar, named after 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 variety of feldspar. Both have a metallic glittery appearance caused by inclusions. The spangled effect is known as aventurescence. Perhaps to avoid confusion, the name sunstone was 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 that is caused by tiny platelets of hematite or goethite. The glitter is usually gold or red, but very occasionally it is green or blue. We have found opaque to transparent specimens in the market. The opaque material is cut as cabochons while the transparent material can be faceted. Some of the cabochons display a discernible star effect and are sold under the name star sunstone.
Sunstone is composed of sodium calcium aluminum silicate, with a hardness of 6 to 6.5 on the Mohs scale. It has a density of 2.62 to 2.65 and a refractive index of 1.525 to 1548. It has perfect cleavage.
Sunstone deposits are found in India, Canada, Madagascar, Norway, Russia and the USA. In 1987 sunstone was declared the state mineral for Oregon in the USA. The Oregon sunstone is rather unique in that it is the only sunstone that contains 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 energy of 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.
- First Published: July-11-2008
- Last Updated: September-15-2017
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