Properties of Sunstone
- Sunstone exhibits an optical effect called schiller due to reflections from inclusions of red copper, hematite, or goethite.
- The appearance of sunstone is similar to aventurine.
- Two kinds of sunstone are distinguished: oligoclase sunstone and orthoclase sunstone.
- The color of sunstone is darkest in the middle and becomes lighter towards the outer edges.
- Unpolished sunstone displays the optical effect caused by inclusions.
- The inclusions in sunstone are hexagonal, rhombic, or irregular in shape.
- The inclusions are parallel to the principal cleavage-plane.
- Aventurine appearance is usually seen in oligoclase feldspar.
- Orthoclase feldspar can also exhibit the aventurine effect.
Distribution of Sunstone
- Sunstone was not popular until recently.
- Sunstone is found in Tvedestrand, near Arendal, in south Norway.
- Other locations where sunstone is found include Lake Baikal in Siberia.
- In the United States, sunstone can be found in Pennsylvania, Oregon, and North Carolina.
- Orthoclase sunstone has been found in New York, Delaware County, Pennsylvania, and Amelia County, Virginia.
- A gemstone called Andesine, resembling sunstone, appeared in the market.
- Many of these gemstones were artificially colored using a copper diffusion process.
- A genuine source of red andesine was eventually verified in Tibet.
- The authenticity of Andesine gemstones sourced from China was debated.
- Independent groups of gemologists confirmed the authenticity of Tibetan red andesine.
- Oregon sunstone is found in Harney County, Oregon, and eastern Lake County.
- Crystals of Oregon sunstone can be quite large.
- The copper content in Oregon sunstone leads to variant colors.
- Oregon Sunstone was designated as the state gemstone of Oregon in 1987.
- Turning one stone of Oregon sunstone can result in manifold hues due to varying copper content.
Sunstone Data Sources