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