Meet the Gemstones: Oregon Sunstone
South Central Oregon features high desert and sage as far as you can see. It’s a place populated with jack rabbits, antelopes, horned toads, and the occasional rattlesnake or scorpion. But it’s also a place where sunstone litters the ground everywhere you step and a field-tripping visitor can get hooked on mining gemstones.
No one would blame you. Because sunstone is beguiling.
ABOVE: This 19.53 carat marquise cut Tanzanian sunstone contains platelets that create the sparkling schiller known as aventurescence in gemstones. Photo Mia Dixon, courtesy Pala International.
What is Sunstone?
Sunstone is a type of feldspar. Feldpsar, like tourmaline, is a group of minerals that are closely related but each is slightly different chemically. Moonstone, amazonite, and labradorite are also feldspar gemstones. Feldspar is also a group in which phenomena seem to pop up.
Sunstone ranges in color from very pale yellow to deep brownish orange. It can also be bi-colored in green and red. Sunstone may contain shiny platelet inclusions that shimmer and sparkle. However, the more inclusions in the gemstones, the muddier the color can be.
The sparkling effect in sunstone gemstones is called schiller or aventurescence. (The effect gives its name to aventurine quartz.) The term is said to have been coined in the 1700s when a worker in an Italian glass factory accidentally knocked a container of copper filings into a batch of glass, ventura meaning “chance” in Italian (according to my small but robust Italian dictionary). It was a fortunate chance as it gave the glass manufacturer something called “goldstone” that was a staple in souvenir shops everywhere in the middle of the 20th century.
Valuing Sunstone Gemstones
As far as sunstone values go, “thin” colors (as the miners call them, meaning the clear and pale yellows), are not usually as highly valued as the red, green, bi-color, or “watermelon” sunstone (stones with a red center and green rind). A high-clarity red stone with a layer of schiller oriented parallel to the table so that the viewer can enjoy both the color and the sparkle is appreciated by many sunstone connoisseurs. Sometimes the schiller may form into patterns, like a lightning bolt, confetti, or a flock of flying geese.
Faceted sunstones one to five carats in size, in pale tones, run $30 to $70 per carat. Those that are more richly colored are priced about $100 to $200 a carat. Larger stones will, of course, have higher per carat costs. All pricing depends on the quality of the color and clarity.
Where to Find Sunstone Gemstones
Sunstone is found in several spots in Oregon, in weathered and partially decomposed basaltic lava flows. It was declared the Oregon State Gemstone in 1987. It is not, however, found exclusively in the Pacific Northwest. And even as relatively recent an entry into the gemstones market as sunstone is, it quickly became the center of a treatment controversy. A paper published in Gems & Gemology in 2013 describes how, in the early 2000s, a red and green gem appeared on the market that was purportedly from either the Congo or Tibet. Eventually, it was determined to be treated, created by diffusing copper into a pale feldspar. The authors explain that the deception, when discovered, “destabilized the market for Oregon sunstone,” which miners have sought to rebuild.
You can search for sunstone yourself. There is a public collection area near Lakeview, Oregon, which is administered by the Bureau of Land Management (BLM). But be aware that there are private claims nearby where miners are digging for sunstone commercially. They will not appreciate you wandering onto their claims, so pay attention to where you are. Facilities are primitive, so contact the BLM in Lakeview to get all the information you need before you go.
Sharon Elaine Thompson is a GG and FGA who has been writing about gemstones and jewelry for Lapidary Journal Jewelry Artist since 1987. She also writes a line of birthstone romance novels under the name Liz Hartley.
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