Oregon sunstone is prized for its transparency. The best Oregon sunstone gems display brilliant shimmer and saturation, unlike most feldspar gemstones, which are opaque or iridescent.
Sunstone is the transparent, gem-quality variety of labradorite, a calcium-rich feldspar in the plagioclase series. It is one of the most popular U.S. gems and is notable for its warm colors and internal schiller (shimmer). Its specific shimmering effect is called aventurescence, uniquely caused by tiny copper platelets within the crystal.
Drummond Gems, Photography by Jeff Mason
Oregon Sunstone Quick Facts
- Mineral: Labradorite (plagioclase feldspar)
- Hardness: 6–6.5
- Color: Yellow, red, green, orange, clear
- Special Feature: Copper aventurescence
- Location: Southeastern Oregon
- State Gemstone: Since 1987
Oregon Sunstone Formation
Oregon sunstone formed in volcanic environments, specifically within the cavities and flows of basalt. Copper gets trapped in sunstones as they form from cooling lava rich in copper. As the crystal grows, tiny flecks of copper become locked inside, creating a sparkling, metallic shimmer. This natural shiller is what gives sunstones their fiery appearance!
Where Oregon Sunstone Is Found
This gemstone is found almost exclusively in southeastern Oregon, particularly in Lake, Harney, and Malheur Counties, with a public collection area in the high desert habitat of south-central Oregon. The Ponderosa and Sunstone Butte mines are well-known sources. Oregon sunstone is the official state gemstone and remains one of the few gemstones in the world with a legally defined geographic origin.
Arkenstone, iRocks.com
Varieties & Colors
Oregon sunstones range in color from clear or pale yellow to rich red, deep green and coppery orange.
The presence and concentration of copper largely determine the color. Reds and greens are considered rare and highly valuable. While some stones exhibit aventurescence, others display color zoning or a bicolor effect, especially in larger crystals. Even though it’s always available on the market, it’s rare from the standpoint that it is gem quality.
Although Native Americans were likely aware of the sparkling stones, Oregon sunstone was formally recognized as a gem material in the early 20th century. Its popularity increased in the 1980s when commercial mining began. Gem cutters and faceters appreciate its hardness (6–6.5 on the Mohs scale of hardness), color range and limited locality. It was designated Oregon’s official state gemstone in 1987.
Metaphysical Properties
In metaphysical circles, Oregon sunstone is said to promote personal power, vitality and independence. It is associated with leadership, confidence, and joy.
Oregon sunstone remains one of the most unique American gemstones, prized for its copper-driven sparkle and limited geographic origin. Whether appreciated for its geology or its beauty, Oregon sunstone continues to stand out among feldspar gems.
This field guide appeared in Rock & Gem magazine. Click here to subscribe. Story by Dr. Stuart Mills and Pam Freeman.
