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Article: Sunstone


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.

Andesine Controversy

  • 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

  • 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

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